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• 61. [Article] Comparing vegetation and soils of remnant and restored prairie wetlands in the northern Willamette Valley

  Native prairies of the Willamette Valley are considered among the rarest of Oregon's ecosystems (Clark and Wilson, 2001). As a result of agriculture conversion, urban development and cessation of native ...

  Citation × Citation Citation Abstract Copy Title: Comparing vegetation and soils of remnant and restored prairie wetlands in the northern Willamette Valley Author: Taylor, Sara M. Native prairies of the Willamette Valley are considered among the rarest of Oregon's ecosystems (Clark and Wilson, 2001). As a result of agriculture conversion, urban development and cessation of native burning, Willamette Valley prairies have become highly fragmented and invaded by non-native species, leaving little room for native plant diversity. Even though wetland prairie conservation and restoration has been a priority for many government agencies there is a need for research on what restoration techniques and management are necessary for increasing native species richness and abundance in remnant and restored wet prairie sites. In this research project, two studies were conducted. In the first study, data were collected on species presence and abundance from three 100m² randomized plots within three remnant wet prairies (Green Mountain, Gotter Prairie South, Knez) and three restored wet prairies (Hutchinson, Gotter Prairie North, Lovejoy) to answer the following research question, 'Are there differences between remnant and restored prairie plant communities with respect to the diversity and abundance of native species?' Analysis of variance and multivariate ordination techniques were used to assess the ecological differences between uncultivated, minimally-managed remnant wet prairies and newly-restored, highly managed wet prairies. Data on soils collected from agricultural sites (Westbrook, Zurcher, Gotter Prairie Ag), as well as the remnant and restored wet prairies mentioned above, were also used to compare soil quality and processes with the remnant and restored wetlands. Restored wet prairie had 23% higher native species cover than remnant prairie (p-value=0.089, N=6). Remnant and restored sites did not differ in native species richness (p-value=0.949, N=6). The relatively high per cent cover of native species at restored sites, (significant at the 10% level), suggests that land managers have successfully restored agricultural properties with an abundance of native species. The lack of significant difference in native species richness between remnant and restored sites also suggests that land managers have also been able to restore native plant diversity into former agricultural properties equivalent to some of the best intact remnant prairies within the Northern Willamette Valley in a short period of time (8 years or less). However, a non-metric scaling (NMS) ordination of the species matrix separated the remnant sites from the restored sites, suggesting that community composition distinguishes restored sites from remnants. The NMS results, which include environmental data in the analysis, also suggest that there is a positive correlation of percent soil moisture and percent soil organic matter associated with the remnant prairies and a positive correlation of management practices such as yearly chemical use, mowing, and clean crops, associated with the restored prairies. The location of Gotter Prairie North restoration within the ordination, between the remnant and restored sites, suggests an intermediate plant composition and soil quality. This could be attributed to intensive weed suppression and soil organic matter build up over time (8 years) in comparison to younger restored sites (3 and 4 years). Indicator species analysis identified many species with high indicator values (IVs) in the remnant prairies; Holcus lanatus, Deschampsia cespitosa, Carex densa and Phalaris arundinacea being the highest. The use of fire as a management tool produced only one species with a high IV (Camassia quamash). In the second study, three seeding treatments (Grass first, Grass and Forb together, Forb first) were compared within a 4 hectare experimental wet prairie unit to answer the research question „Which of the three seeding treatments used leads to the highest native species abundance and species richness?‟ Results from an analysis of variance indicated significant differences between treatments in native species richness for 2009 and 2010 (p-values=0.002 & 0.004 respectively) at the 5% level and native species abundance in 2010 only (p-value=0.099) at the 10% level. The Grass and Forb and Forb first treatments were highest in native species richness for 2009 and 2010, whereas the Grass and Forb and Grass first treatments were highest in native species abundance in 2010. A NMS ordination suggests that Juncus tenuis is one of the dominant species, in all seeding treatments, after one year of growth. Title: Comparing vegetation and soils of remnant and restored prairie wetlands in the northern Willamette Valley Author: Taylor, Sara M. Native prairies of the Willamette Valley are considered among the rarest of Oregon's ecosystems (Clark and Wilson, 2001). As a result of agriculture conversion, urban development and cessation of native burning, Willamette Valley prairies have become highly fragmented and invaded by non-native species, leaving little room for native plant diversity. Even though wetland prairie conservation and restoration has been a priority for many government agencies there is a need for research on what restoration techniques and management are necessary for increasing native species richness and abundance in remnant and restored wet prairie sites. In this research project, two studies were conducted. In the first study, data were collected on species presence and abundance from three 100m² randomized plots within three remnant wet prairies (Green Mountain, Gotter Prairie South, Knez) and three restored wet prairies (Hutchinson, Gotter Prairie North, Lovejoy) to answer the following research question, 'Are there differences between remnant and restored prairie plant communities with respect to the diversity and abundance of native species?' Analysis of variance and multivariate ordination techniques were used to assess the ecological differences between uncultivated, minimally-managed remnant wet prairies and newly-restored, highly managed wet prairies. Data on soils collected from agricultural sites (Westbrook, Zurcher, Gotter Prairie Ag), as well as the remnant and restored wet prairies mentioned above, were also used to compare soil quality and processes with the remnant and restored wetlands. Restored wet prairie had 23% higher native species cover than remnant prairie (p-value=0.089, N=6). Remnant and restored sites did not differ in native species richness (p-value=0.949, N=6). The relatively high per cent cover of native species at restored sites, (significant at the 10% level), suggests that land managers have successfully restored agricultural properties with an abundance of native species. The lack of significant difference in native species richness between remnant and restored sites also suggests that land managers have also been able to restore native plant diversity into former agricultural properties equivalent to some of the best intact remnant prairies within the Northern Willamette Valley in a short period of time (8 years or less). However, a non-metric scaling (NMS) ordination of the species matrix separated the remnant sites from the restored sites, suggesting that community composition distinguishes restored sites from remnants. The NMS results, which include environmental data in the analysis, also suggest that there is a positive correlation of percent soil moisture and percent soil organic matter associated with the remnant prairies and a positive correlation of management practices such as yearly chemical use, mowing, and clean crops, associated with the restored prairies. The location of Gotter Prairie North restoration within the ordination, between the remnant and restored sites, suggests an intermediate plant composition and soil quality. This could be attributed to intensive weed suppression and soil organic matter build up over time (8 years) in comparison to younger restored sites (3 and 4 years). Indicator species analysis identified many species with high indicator values (IVs) in the remnant prairies; Holcus lanatus, Deschampsia cespitosa, Carex densa and Phalaris arundinacea being the highest. The use of fire as a management tool produced only one species with a high IV (Camassia quamash). In the second study, three seeding treatments (Grass first, Grass and Forb together, Forb first) were compared within a 4 hectare experimental wet prairie unit to answer the research question „Which of the three seeding treatments used leads to the highest native species abundance and species richness?‟ Results from an analysis of variance indicated significant differences between treatments in native species richness for 2009 and 2010 (p-values=0.002 & 0.004 respectively) at the 5% level and native species abundance in 2010 only (p-value=0.099) at the 10% level. The Grass and Forb and Forb first treatments were highest in native species richness for 2009 and 2010, whereas the Grass and Forb and Grass first treatments were highest in native species abundance in 2010. A NMS ordination suggests that Juncus tenuis is one of the dominant species, in all seeding treatments, after one year of growth. Close

• 62. [Article] Reducing energy inputs in Oregon vegetable production to enhance economic and environmental sustainability: A final report submitted to the Oregon Processed Vegetable Commission, 2009

  Energy input comparisons between tillage systems; evaluation of the value of legumes as part of a cover crop mixture used in strip-till sweet corn production; evaluation of the nitrogen contribution of ...

  Citation × Citation Citation Abstract Copy Title: Reducing energy inputs in Oregon vegetable production to enhance economic and environmental sustainability: A final report submitted to the Oregon Processed Vegetable Commission, 2009 Author: Luna, John M. Energy input comparisons between tillage systems; evaluation of the value of legumes as part of a cover crop mixture used in strip-till sweet corn production; evaluation of the nitrogen contribution of legume-based cover crops to organic vegetable production. Title: Reducing energy inputs in Oregon vegetable production to enhance economic and environmental sustainability: A final report submitted to the Oregon Processed Vegetable Commission, 2009 Author: Luna, John M. Energy input comparisons between tillage systems; evaluation of the value of legumes as part of a cover crop mixture used in strip-till sweet corn production; evaluation of the nitrogen contribution of legume-based cover crops to organic vegetable production. Close

• 63. [Article] Comparative wintering ecology of two subspecies of sandhill crane : informing conservation planning in the Sacramento-San Joaquin River Delta region of California

  California's Central Valley agricultural landscapes provide several important wintering regions for Pacific Flyway sandhill crane (Grus canadensis) populations; however, the value of those regions is being ...

  Citation × Citation Citation Abstract Copy Title: Comparative wintering ecology of two subspecies of sandhill crane : informing conservation planning in the Sacramento-San Joaquin River Delta region of California Author: Ivey, Gary L. California's Central Valley agricultural landscapes provide several important wintering regions for Pacific Flyway sandhill crane (Grus canadensis) populations; however, the value of those regions is being compromised by urban expansion, other developments, and conversions to incompatible crop types. Greater (G. c. tabida) and lesser sandhill cranes (G. c. canadensis) both have special conservation status in California; the greater is listed as threatened and the lesser as a bird species of conservation concern by the state. However, basic information about their wintering ecology has been lacking to design biologically sound conservation strategies to maintain their wintering habitats. My study of sandhill cranes focused on one major Central Valley wintering region, the Sacramento-San Joaquin River Delta (Delta). I compared daily movements and winter site fidelity between the two sandhill crane subspecies, evaluated the timing of crane arrival and departure from the region, assessed foraging habitat choices, measured abundance and distribution in the Delta, documented the characteristics of roost sites, and developed habitat conservation models and decision tools for managers to facilitate habitat conservation and management. Both crane subspecies showed strong fidelity to my Delta study area. Foraging flights from roost sites were shorter for greaters than lesser (1.2 ± 0.4 km vs. 3.1 ± 0.1 km, respectively) and consequently, mean size of 95% fixed kernel winter home ranges was an order of magnitude smaller for greaters (1.9 ± 0.4 km² vs.21.9 ± 1.9 km², respectively). The strong site fidelity of greaters to roost complexes within landscapes in the Delta indicates that conservation planning targeted at maintaining and managing for adequate food resources around traditional roost sites can be effective for meeting sandhill crane habitat needs, while the scale of conservation differs by subspecies. I recommend that conservation planning actions consider all habitats within 5 km of a crane roost as a sandhill crane conservation "ecosystem unit." This radius encompasses 95% and 69% of the flights from roosts to foraging location (commuting flights) made by greaters and lessers, respectively. For lessers, a conservation radius of 10 km would encompass 90% of the commuting flights. Management, mitigation, acquisition, easement, planning, and farm subsidy programs intended to benefit cranes will be most effective when applied at these scales. Within these radii, conservation and management of wintering habitats should include creating both new roost and feeding areas to ensure high chances of successful use. Sandhill cranes used major crops and habitat types available in the landscapes surrounding their roost sites and focused most of their foraging in grain crops. They generally avoided dry corn stubble, selected dry rice stubble early in the season, and rarely used dry wild rice stubble. Tilled fields were also usually avoided but were occasionally used shortly after tillage. Mulched corn ranked high in comparison to other corn treatments while mulched rice use was used similarly to dry rice stubble. Both subspecies often highly favored cropland habitats when they were initially flooded. Cranes were attracted to new plantings of pasture and winter wheat. One important difference between the subspecies was that lessers used alfalfa which was generally avoided by greaters. Dry corn stubble was avoided while dry rice stubble was favored early in winter. If wildlife managers want to encourage winter field use by cranes they could provide incentives for favorable practices such as production of grain crops, reduction or delaying tillage and flooding of grain fields, provision of irrigations to some crop types, and increasing the practice of mulching of corn stubble. Of the 69 crane night roosts I identified, 35 were flooded cropland sites and 34 were wetland sites. I found that both larger individual roost sites and larger complexes of roost sites supported larger peak numbers of cranes. Water depth used by roosting cranes averaged 10 cm (range 3-21 cm, mode 7 cm) and was similar between subspecies. Roosting cranes avoided sites that were regularly hunted or had high densities (i.e., > 1 blind/5 ha) of hunting blinds. Roost site design and management should consider providing and maintaining large roost complexes (100 - 1000 ha) ideally in close proximity (< 5 km) to other roost sites, with large individual sites (> 5 ha) of mostly level topography, dominated by shallow water (5-10 cm depths). The fact that cranes readily use undisturbed flooded cropland sites makes this a viable option for creation of roost habitat. Because hunting disturbance can limit crane use of roost sites I suggest these two uses should not be considered compatible. However, if the management objective of an area includes waterfowl hunting, limiting hunting at low blind densities (i.e., < 1 blind/60 ha) and restricting hunting to early morning may be viable options for creating a crane-compatible waterfowl hunt program. Radio-marked sandhill cranes arrived in the Delta beginning 3 October, most arrived in mid-October, and the last radio-marked sandhill crane arrived on 10 December. Departure dates ranged from 15 January to 13 March. Mean arrival and departure dates were similar between subspecies. From mid-December through early-February in 2007-2008, the Delta population ranged from 20,000 to 27,000 sandhill cranes. Abundance varied at the main roost sites during winter, likely because sandhill cranes responded to changes in water and foraging habitat conditions. Sandhill cranes used an area of approximately 1,500 km² for foraging. Estimated peak abundance in the Delta was more than half the total number counted on recent Pacific Flyway midwinter surveys, indicating the Delta region is a key area for efforts in conservation and recovery of wintering sandhill cranes in California. Based on arrival dates, flooding of sandhill crane roost sites should be staggered with some sites flooded in early September and most sites flooded by early October. Maintaining flooding of at least some roost sites through mid-March would provide essential roosting habitat until most birds have departed the Delta region on spring migration. Not all 5-km radius ecosystem units are equal in their value to greater sandhill cranes, and the relative foraging value of a particular parcel within an ecosystem unit depends on the numbers of cranes using the focal roost site, the habitat choices they make, and the probability that they will fly to a particular parcel. Additionally, some ecosystem units overlap, and in these overlap zones, the probability of crane use is higher, because of additive effects. To provide a tool to allow managers to further refine management plans, I developed a model which allows more specific focus of crane conservation, mitigation and habitat management, using what my study revealed about greater sandhill cranes. This model considers the abundance of greaters at individual roost sites and the probability that they would fly to a given location. Sites closer to roosts had a higher probability of crane use. I calculated the probability that greaters would fly to a parcel within concentric 1-km intervals as a product of the proportion of commuting flights of individuals that reached that interval, and the proportion of all commuting flights that reached that interval. Within crane ecosystem units, it is important to protect the existing habitat from further loss and optimize foraging conditions for cranes. I provide a decision matrix to assist with plans to enhance existing crane landscapes, create new crane habitat areas or mitigate habitat losses. This matrix provides a framework for decision-making regarding enhancing sandhill crane foraging and roost site habitats. Wildlife managers could employ a variety of tools to conserve and manage crane habitats, including fee title acquisitions, private conservation easements, and specific cropland management actions to maintain crane-compatible conditions and high food values for cranes (possibly including providing unharvested food plots). My study has demonstrated that most cranes use a relatively small landscape surrounding their traditional roost sites and that they favor certain crops and post-harvest crop management practices for foraging. However, we need a better understanding of the actual carrying capacity for cranes in these crane management zones to ensure that managers can maintain these sites for cranes in the future. Title: Comparative wintering ecology of two subspecies of sandhill crane : informing conservation planning in the Sacramento-San Joaquin River Delta region of California Author: Ivey, Gary L. California's Central Valley agricultural landscapes provide several important wintering regions for Pacific Flyway sandhill crane (Grus canadensis) populations; however, the value of those regions is being compromised by urban expansion, other developments, and conversions to incompatible crop types. Greater (G. c. tabida) and lesser sandhill cranes (G. c. canadensis) both have special conservation status in California; the greater is listed as threatened and the lesser as a bird species of conservation concern by the state. However, basic information about their wintering ecology has been lacking to design biologically sound conservation strategies to maintain their wintering habitats. My study of sandhill cranes focused on one major Central Valley wintering region, the Sacramento-San Joaquin River Delta (Delta). I compared daily movements and winter site fidelity between the two sandhill crane subspecies, evaluated the timing of crane arrival and departure from the region, assessed foraging habitat choices, measured abundance and distribution in the Delta, documented the characteristics of roost sites, and developed habitat conservation models and decision tools for managers to facilitate habitat conservation and management. Both crane subspecies showed strong fidelity to my Delta study area. Foraging flights from roost sites were shorter for greaters than lesser (1.2 ± 0.4 km vs. 3.1 ± 0.1 km, respectively) and consequently, mean size of 95% fixed kernel winter home ranges was an order of magnitude smaller for greaters (1.9 ± 0.4 km² vs.21.9 ± 1.9 km², respectively). The strong site fidelity of greaters to roost complexes within landscapes in the Delta indicates that conservation planning targeted at maintaining and managing for adequate food resources around traditional roost sites can be effective for meeting sandhill crane habitat needs, while the scale of conservation differs by subspecies. I recommend that conservation planning actions consider all habitats within 5 km of a crane roost as a sandhill crane conservation "ecosystem unit." This radius encompasses 95% and 69% of the flights from roosts to foraging location (commuting flights) made by greaters and lessers, respectively. For lessers, a conservation radius of 10 km would encompass 90% of the commuting flights. Management, mitigation, acquisition, easement, planning, and farm subsidy programs intended to benefit cranes will be most effective when applied at these scales. Within these radii, conservation and management of wintering habitats should include creating both new roost and feeding areas to ensure high chances of successful use. Sandhill cranes used major crops and habitat types available in the landscapes surrounding their roost sites and focused most of their foraging in grain crops. They generally avoided dry corn stubble, selected dry rice stubble early in the season, and rarely used dry wild rice stubble. Tilled fields were also usually avoided but were occasionally used shortly after tillage. Mulched corn ranked high in comparison to other corn treatments while mulched rice use was used similarly to dry rice stubble. Both subspecies often highly favored cropland habitats when they were initially flooded. Cranes were attracted to new plantings of pasture and winter wheat. One important difference between the subspecies was that lessers used alfalfa which was generally avoided by greaters. Dry corn stubble was avoided while dry rice stubble was favored early in winter. If wildlife managers want to encourage winter field use by cranes they could provide incentives for favorable practices such as production of grain crops, reduction or delaying tillage and flooding of grain fields, provision of irrigations to some crop types, and increasing the practice of mulching of corn stubble. Of the 69 crane night roosts I identified, 35 were flooded cropland sites and 34 were wetland sites. I found that both larger individual roost sites and larger complexes of roost sites supported larger peak numbers of cranes. Water depth used by roosting cranes averaged 10 cm (range 3-21 cm, mode 7 cm) and was similar between subspecies. Roosting cranes avoided sites that were regularly hunted or had high densities (i.e., > 1 blind/5 ha) of hunting blinds. Roost site design and management should consider providing and maintaining large roost complexes (100 - 1000 ha) ideally in close proximity (< 5 km) to other roost sites, with large individual sites (> 5 ha) of mostly level topography, dominated by shallow water (5-10 cm depths). The fact that cranes readily use undisturbed flooded cropland sites makes this a viable option for creation of roost habitat. Because hunting disturbance can limit crane use of roost sites I suggest these two uses should not be considered compatible. However, if the management objective of an area includes waterfowl hunting, limiting hunting at low blind densities (i.e., < 1 blind/60 ha) and restricting hunting to early morning may be viable options for creating a crane-compatible waterfowl hunt program. Radio-marked sandhill cranes arrived in the Delta beginning 3 October, most arrived in mid-October, and the last radio-marked sandhill crane arrived on 10 December. Departure dates ranged from 15 January to 13 March. Mean arrival and departure dates were similar between subspecies. From mid-December through early-February in 2007-2008, the Delta population ranged from 20,000 to 27,000 sandhill cranes. Abundance varied at the main roost sites during winter, likely because sandhill cranes responded to changes in water and foraging habitat conditions. Sandhill cranes used an area of approximately 1,500 km² for foraging. Estimated peak abundance in the Delta was more than half the total number counted on recent Pacific Flyway midwinter surveys, indicating the Delta region is a key area for efforts in conservation and recovery of wintering sandhill cranes in California. Based on arrival dates, flooding of sandhill crane roost sites should be staggered with some sites flooded in early September and most sites flooded by early October. Maintaining flooding of at least some roost sites through mid-March would provide essential roosting habitat until most birds have departed the Delta region on spring migration. Not all 5-km radius ecosystem units are equal in their value to greater sandhill cranes, and the relative foraging value of a particular parcel within an ecosystem unit depends on the numbers of cranes using the focal roost site, the habitat choices they make, and the probability that they will fly to a particular parcel. Additionally, some ecosystem units overlap, and in these overlap zones, the probability of crane use is higher, because of additive effects. To provide a tool to allow managers to further refine management plans, I developed a model which allows more specific focus of crane conservation, mitigation and habitat management, using what my study revealed about greater sandhill cranes. This model considers the abundance of greaters at individual roost sites and the probability that they would fly to a given location. Sites closer to roosts had a higher probability of crane use. I calculated the probability that greaters would fly to a parcel within concentric 1-km intervals as a product of the proportion of commuting flights of individuals that reached that interval, and the proportion of all commuting flights that reached that interval. Within crane ecosystem units, it is important to protect the existing habitat from further loss and optimize foraging conditions for cranes. I provide a decision matrix to assist with plans to enhance existing crane landscapes, create new crane habitat areas or mitigate habitat losses. This matrix provides a framework for decision-making regarding enhancing sandhill crane foraging and roost site habitats. Wildlife managers could employ a variety of tools to conserve and manage crane habitats, including fee title acquisitions, private conservation easements, and specific cropland management actions to maintain crane-compatible conditions and high food values for cranes (possibly including providing unharvested food plots). My study has demonstrated that most cranes use a relatively small landscape surrounding their traditional roost sites and that they favor certain crops and post-harvest crop management practices for foraging. However, we need a better understanding of the actual carrying capacity for cranes in these crane management zones to ensure that managers can maintain these sites for cranes in the future. Close

• 64. [Article] Impacts of high biomass cover crop management on soil factors and corn root rot and productivity: Report to the Oregon Processed Vegetable Commission, 2006

  Objective: to evaluate the impacts of N availability, microbial activity, and root health on corn productivity and yield in high biomass cover crop systems

  Citation × Citation Citation Abstract Copy Title: Impacts of high biomass cover crop management on soil factors and corn root rot and productivity: Report to the Oregon Processed Vegetable Commission, 2006 Author: Stone, Alex, Miyazoe, Mikio Objective: to evaluate the impacts of N availability, microbial activity, and root health on corn productivity and yield in high biomass cover crop systems Title: Impacts of high biomass cover crop management on soil factors and corn root rot and productivity: Report to the Oregon Processed Vegetable Commission, 2006 Author: Stone, Alex, Miyazoe, Mikio Objective: to evaluate the impacts of N availability, microbial activity, and root health on corn productivity and yield in high biomass cover crop systems Close

• 65. [Article] "AmaRosa," a Red Skinned, Red Fleshed Fingerling with High Phytonutrient Value

  This is the publisher’s final pdf. The article is copyrighted by the Potato Association of America and published by Springer. It can be found at: http://www.springerlink.com/content/1099-209x/. To the ...

  Citation × Citation Citation Abstract Copy Title: "AmaRosa," a Red Skinned, Red Fleshed Fingerling with High Phytonutrient Value Author: Novy, Richard, Stark, Jeff, Feibert, Eric, Vales, Isabel, Whitworth, Jonathan, Navarre, Roy, Quick, Richard, Pavek, Mark, Brown, Charles R., Miller, J. Creighton, Jr., Yilma, Solomon, Hane, Dan, Culp, Darrin, Holm, David, James, Steven, Charlton, Brian, Shock, Clinton, Knowles, Richard This is the publisher’s final pdf. The article is copyrighted by the Potato Association of America and published by Springer. It can be found at: http://www.springerlink.com/content/1099-209x/. To the best of our knowledge, one or more authors of this paper were federal employees when contributing to this work. Title: "AmaRosa," a Red Skinned, Red Fleshed Fingerling with High Phytonutrient Value Author: Novy, Richard, Stark, Jeff, Feibert, Eric, Vales, Isabel, Whitworth, Jonathan, Navarre, Roy, Quick, Richard, Pavek, Mark, Brown, Charles R., Miller, J. Creighton, Jr., Yilma, Solomon, Hane, Dan, Culp, Darrin, Holm, David, James, Steven, Charlton, Brian, Shock, Clinton, Knowles, Richard This is the publisher’s final pdf. The article is copyrighted by the Potato Association of America and published by Springer. It can be found at: http://www.springerlink.com/content/1099-209x/. To the best of our knowledge, one or more authors of this paper were federal employees when contributing to this work. Close

• 66. [Article] Development of a 10,000 Locus Genetic Map of the Sunflower Genome Based on Multiple Crosses

  This is the publisher’s final pdf. The published article is copyrighted by Genetics Society of America and can be found at: http://www.g3journal.org/.

  Citation × Citation Citation Abstract Copy Title: Development of a 10,000 Locus Genetic Map of the Sunflower Genome Based on Multiple Crosses Author: Brunick, Robert L., Bowers, John E., Burke, John M., Knapp, Steven J., Rieseberg, Loren H., Bachlava, Eleni This is the publisher’s final pdf. The published article is copyrighted by Genetics Society of America and can be found at: http://www.g3journal.org/. Title: Development of a 10,000 Locus Genetic Map of the Sunflower Genome Based on Multiple Crosses Author: Brunick, Robert L., Bowers, John E., Burke, John M., Knapp, Steven J., Rieseberg, Loren H., Bachlava, Eleni This is the publisher’s final pdf. The published article is copyrighted by Genetics Society of America and can be found at: http://www.g3journal.org/. Close

• 67. [Image] Value of cultivated crop in rotation

  	Value of cultivated crop in rotation. Half this field in corn and half in spring outs previously - Yamhill County
  	Citation × Citation Citation Abstract Copy Title: Value of cultivated crop in rotation Value of cultivated crop in rotation. Half this field in corn and half in spring outs previously - Yamhill County Title: Value of cultivated crop in rotation Value of cultivated crop in rotation. Half this field in corn and half in spring outs previously - Yamhill County Close

• 68. [Article] Heritability estimates and associations for protein content and grain yield involving four winter wheat crosses (Triticum aestivum Vill., Host)

  Four agronomically and genetically diverse winter wheat parents were utilized as the experimental organisms. Atlas 66 and NB 68513 were selected as cultivars with a high and stable protein content when grown ...

  Citation × Citation Citation Abstract Copy Title: Heritability estimates and associations for protein content and grain yield involving four winter wheat crosses (Triticum aestivum Vill., Host) Author: Solen, Polat Four agronomically and genetically diverse winter wheat parents were utilized as the experimental organisms. Atlas 66 and NB 68513 were selected as cultivars with a high and stable protein content when grown under different environmental condidtions. They are intermediate for grain yield when grown in the Pacific Northwest. Yamhill and Hyslop represented low protein, high yielding cultivars adapted to the Pacific Northwest. Data were obtained from crosses between the two high protein cultivars and the two low protein cultivars based on the performance of the parents and the F₁ and F₂ generations. These experimental populations were grown in 1971 at the Pendleton Experiment Station and the Central Oregon Experimental site at Madras, Oregon. Measurements were made on an individual plant basis for protein content, grain yield, 50 kernel weight, kernels per spike, tillers per plant and plant height. Differences among and within crosses were determined by the analysis of variance. Information concerning the nature of inheritance was obtained by comparing the F₁ and F₂ means in relation to performance of the parents; the frequency distribution of the generations for protein content; and by determining broad and narrow sense heritability estimates for the six characters studied. The existence of possible phenotypic associations among the six characters studied was determined by using correlation coefficients. In order to evaluate the possible direct and indirect effects of grain yield and the components of yield on protein content, path coefficient analyses were employed. Significant differences were observed among and within crosses at both the Pendleton and Madras sites for most characters measured. The F₁ and F₂ mean values were found to be near the mid-parent of the two parents in all four crosses for plant height, 50 kernel weight and kernels per spike. There were several exceptions depending on the particular cross and specific character. Protein content mean values were also intermediate between the two parents for the F₁ and F₂ generations. In crosses involving Hyslop, the mean values tended to be near the highest parent. Little or no transgressive segregation was noted in the F₂ generation. Evidence of non additive gene action was noted both for grain yield and tiller number in the F₁ and F₂ generations with the mean values exceeding the highest parent in all crosses for grain yield at the Pendleton site. Tillers per plant at Pendleton and both tillers per plant and grain yield at Madras also showed some degree of hybrid vigor, but the magnitude depended on the particular cross. The high broad and narrow sense heritability estimates obtained both at Pendleton and Madras for all traits suggested that there was a large amount of genetic variation present for the characters studied. The narrow sense estimates further suggested that a high percentage of the total genetic variation was due to genes which function in an additive manner. Significant negative correlations were noted between protein content and grain yield including some of the components of yield. In evaluating the direct and indirect effects with path coefficient analysis, these negative associations resulted from the large negative indirect effects of 50 kernel weight and kernels per spike on protein content via grain yield at the Madras site. At the Pendleton site, where moisture became a limiting factor, the negative association resulted largely as the indirect effect of 50 kernel weight on protein content through grain yield. The large environmental influence on protein content was particularly striking at the Pendleton site. With the spring application of nitrogen, a delay in maturity for Hyslop and Yamhill was noted and with the subsequent loss of moisture, shriveled grain resulted and hence a higher protein content with lower grain yield. This resulted in the grain protein of Hyslop and Yamhill being higher than that of Atlas 66 and NB 68513. The results of this study suggest that it may be necessary to compromise in attempting to develop high protein lines with maximum yield. However, it should be possible to increase the protein content two to three percent and still maintain the yielding ability of Hyslop and Yamhill. Title: Heritability estimates and associations for protein content and grain yield involving four winter wheat crosses (Triticum aestivum Vill., Host) Author: Solen, Polat Four agronomically and genetically diverse winter wheat parents were utilized as the experimental organisms. Atlas 66 and NB 68513 were selected as cultivars with a high and stable protein content when grown under different environmental condidtions. They are intermediate for grain yield when grown in the Pacific Northwest. Yamhill and Hyslop represented low protein, high yielding cultivars adapted to the Pacific Northwest. Data were obtained from crosses between the two high protein cultivars and the two low protein cultivars based on the performance of the parents and the F₁ and F₂ generations. These experimental populations were grown in 1971 at the Pendleton Experiment Station and the Central Oregon Experimental site at Madras, Oregon. Measurements were made on an individual plant basis for protein content, grain yield, 50 kernel weight, kernels per spike, tillers per plant and plant height. Differences among and within crosses were determined by the analysis of variance. Information concerning the nature of inheritance was obtained by comparing the F₁ and F₂ means in relation to performance of the parents; the frequency distribution of the generations for protein content; and by determining broad and narrow sense heritability estimates for the six characters studied. The existence of possible phenotypic associations among the six characters studied was determined by using correlation coefficients. In order to evaluate the possible direct and indirect effects of grain yield and the components of yield on protein content, path coefficient analyses were employed. Significant differences were observed among and within crosses at both the Pendleton and Madras sites for most characters measured. The F₁ and F₂ mean values were found to be near the mid-parent of the two parents in all four crosses for plant height, 50 kernel weight and kernels per spike. There were several exceptions depending on the particular cross and specific character. Protein content mean values were also intermediate between the two parents for the F₁ and F₂ generations. In crosses involving Hyslop, the mean values tended to be near the highest parent. Little or no transgressive segregation was noted in the F₂ generation. Evidence of non additive gene action was noted both for grain yield and tiller number in the F₁ and F₂ generations with the mean values exceeding the highest parent in all crosses for grain yield at the Pendleton site. Tillers per plant at Pendleton and both tillers per plant and grain yield at Madras also showed some degree of hybrid vigor, but the magnitude depended on the particular cross. The high broad and narrow sense heritability estimates obtained both at Pendleton and Madras for all traits suggested that there was a large amount of genetic variation present for the characters studied. The narrow sense estimates further suggested that a high percentage of the total genetic variation was due to genes which function in an additive manner. Significant negative correlations were noted between protein content and grain yield including some of the components of yield. In evaluating the direct and indirect effects with path coefficient analysis, these negative associations resulted from the large negative indirect effects of 50 kernel weight and kernels per spike on protein content via grain yield at the Madras site. At the Pendleton site, where moisture became a limiting factor, the negative association resulted largely as the indirect effect of 50 kernel weight on protein content through grain yield. The large environmental influence on protein content was particularly striking at the Pendleton site. With the spring application of nitrogen, a delay in maturity for Hyslop and Yamhill was noted and with the subsequent loss of moisture, shriveled grain resulted and hence a higher protein content with lower grain yield. This resulted in the grain protein of Hyslop and Yamhill being higher than that of Atlas 66 and NB 68513. The results of this study suggest that it may be necessary to compromise in attempting to develop high protein lines with maximum yield. However, it should be possible to increase the protein content two to three percent and still maintain the yielding ability of Hyslop and Yamhill. Close

• 69. [Article] Effects of Cover Crop Management on Vine Development and Fruit Quality of Pinot noir - Year 1 Report

  Item has been restricted to administrators only at the request of the author.

  Citation × Citation Citation Abstract Copy Title: Effects of Cover Crop Management on Vine Development and Fruit Quality of Pinot noir - Year 1 Report Author: Skinkis, Patty, Fredrikson, Levi Item has been restricted to administrators only at the request of the author. Title: Effects of Cover Crop Management on Vine Development and Fruit Quality of Pinot noir - Year 1 Report Author: Skinkis, Patty, Fredrikson, Levi Item has been restricted to administrators only at the request of the author. Close

• 70. [Article] Evaluation of Rhizobium strains with three Mediterranean forage legumes for biological nitrogen fixation

  Centuries of continuous grain cropping in northern Africa have reduced N levels in soils to a degree such that agricultural production is now largely dependent upon nitrogen fertilizer. Through the identification ...

  Citation × Citation Citation Abstract Copy Title: Evaluation of Rhizobium strains with three Mediterranean forage legumes for biological nitrogen fixation Author: Streeter, Donald J. Centuries of continuous grain cropping in northern Africa have reduced N levels in soils to a degree such that agricultural production is now largely dependent upon nitrogen fertilizer. Through the identification of highly effective legume and Rhizobium strain combinations, the production of protein-rich livestock forage and green manure can be substantially increased. Three common Mediterranean legumes, Lupinus albus, Medicago truncatula, and Trifolium alexandrium were chosen to be tested with various strains of Rhizobium. Greenhouse and growth chamber experiments were conducted to evaluate these forage legumes with commercially available Rhizobium inoculum, nodule isolates collected in Tunisia, and nodule isolates from other sources. Strain effectiveness was determined following 6 weeks of growth in plant tubes containing nutrient agar or modified Leonard jars containing nutrient solution. Each symbiotic system was evaluated for shoot, root, and nodule dry weight, nodule number, nodule acetylene reduction activity, and total plant N. For L. albus, four single strains, 96A5, 96A19, 96B15, and 96B23, and one commercially available multiple strain 'H', produced acetylene reduction activity from 100 to 190 u moles ethylene evolved.h⁻¹.g⁻¹ dw of nodules. Plant dry weights and total plant N values were comparable to the +N treatment. All five strains were therefore recommended for further evaluation under field conditions. Two single strains for M. truncatula, 102D6 and 102B11, produced acetylene reduction values from 800 to 900 u moles ethylene evolved. h⁻¹.g⁻¹ dw of nodules (1.5-5.1 umoles.h⁻¹.plant⁻¹). Plant dry weights and total plant N values were higher than the +N treatment. Both strains were recommended for further evaluation under field conditions. Strains WCI-1 and 162X95 for T. alexandrium produced acetylene reduction activity from 900 to 1000 u moles ethylene evolved.h⁻¹.g⁻¹ dw of nodules (1.9-11.4 umoles.h⁻¹.plant⁻¹). Plant dry weights were 50%, and total plant N 80%, of the +N treatment. Both strains were recommended for further evaluation under field conditions. Further evaluation of these strains in field trials is recommended. These trials should be performed in the area of eventual use or with soil and climatic conditions typical of the production area. Title: Evaluation of Rhizobium strains with three Mediterranean forage legumes for biological nitrogen fixation Author: Streeter, Donald J. Centuries of continuous grain cropping in northern Africa have reduced N levels in soils to a degree such that agricultural production is now largely dependent upon nitrogen fertilizer. Through the identification of highly effective legume and Rhizobium strain combinations, the production of protein-rich livestock forage and green manure can be substantially increased. Three common Mediterranean legumes, Lupinus albus, Medicago truncatula, and Trifolium alexandrium were chosen to be tested with various strains of Rhizobium. Greenhouse and growth chamber experiments were conducted to evaluate these forage legumes with commercially available Rhizobium inoculum, nodule isolates collected in Tunisia, and nodule isolates from other sources. Strain effectiveness was determined following 6 weeks of growth in plant tubes containing nutrient agar or modified Leonard jars containing nutrient solution. Each symbiotic system was evaluated for shoot, root, and nodule dry weight, nodule number, nodule acetylene reduction activity, and total plant N. For L. albus, four single strains, 96A5, 96A19, 96B15, and 96B23, and one commercially available multiple strain 'H', produced acetylene reduction activity from 100 to 190 u moles ethylene evolved.h⁻¹.g⁻¹ dw of nodules. Plant dry weights and total plant N values were comparable to the +N treatment. All five strains were therefore recommended for further evaluation under field conditions. Two single strains for M. truncatula, 102D6 and 102B11, produced acetylene reduction values from 800 to 900 u moles ethylene evolved. h⁻¹.g⁻¹ dw of nodules (1.5-5.1 umoles.h⁻¹.plant⁻¹). Plant dry weights and total plant N values were higher than the +N treatment. Both strains were recommended for further evaluation under field conditions. Strains WCI-1 and 162X95 for T. alexandrium produced acetylene reduction activity from 900 to 1000 u moles ethylene evolved.h⁻¹.g⁻¹ dw of nodules (1.9-11.4 umoles.h⁻¹.plant⁻¹). Plant dry weights were 50%, and total plant N 80%, of the +N treatment. Both strains were recommended for further evaluation under field conditions. Further evaluation of these strains in field trials is recommended. These trials should be performed in the area of eventual use or with soil and climatic conditions typical of the production area. Close

• 71. [Article] High-context and low-context cultures: value system variations for American and Japanese university students and their resultant communication patterns

  This exploratory investigation focused on the validity of the concepts of high-context and low-context as a meaningful and powerful construct for examining cultural differences. Specifically, American ...

  Citation × Citation Citation Abstract Copy Title: High-context and low-context cultures: value system variations for American and Japanese university students and their resultant communication patterns Author: Yamaguchi, Shinobu Yume This exploratory investigation focused on the validity of the concepts of high-context and low-context as a meaningful and powerful construct for examining cultural differences. Specifically, American and Japanese value differences and communication patterns were examined. The study tested the hypotheses that Japanese students would rank high-context group orientation values higher than American students, and American students would rank low-context individual values higher than Japanese students. Other value differences and similarities were explored. The data were collected from American university students and Japanese university students. Subjects were drawn from Oregon State University for American students, and from Aoyama Gakuin University in Tokyo for Japanese students. Statistical analysis of rank order data showed Japanese university students ranked highly on group orientation values, supporting the first hypothesis, while American university students ranked highly on individual orientation values, supporting the second hypothesis. The general results of this exploratory study were interpreted as supporting Hall's concepts of high-context and low-context cultural differences. Title: High-context and low-context cultures: value system variations for American and Japanese university students and their resultant communication patterns Author: Yamaguchi, Shinobu Yume This exploratory investigation focused on the validity of the concepts of high-context and low-context as a meaningful and powerful construct for examining cultural differences. Specifically, American and Japanese value differences and communication patterns were examined. The study tested the hypotheses that Japanese students would rank high-context group orientation values higher than American students, and American students would rank low-context individual values higher than Japanese students. Other value differences and similarities were explored. The data were collected from American university students and Japanese university students. Subjects were drawn from Oregon State University for American students, and from Aoyama Gakuin University in Tokyo for Japanese students. Statistical analysis of rank order data showed Japanese university students ranked highly on group orientation values, supporting the first hypothesis, while American university students ranked highly on individual orientation values, supporting the second hypothesis. The general results of this exploratory study were interpreted as supporting Hall's concepts of high-context and low-context cultural differences. Close

• 72. [Article] Ethical Considerations of Transgenic Biotechnology as a Tool to Address Global Food Insecurity: Implementation and Regulation in Developing Countries

  Transgenic biotechnology holds enormous potential as a tool to address global food insecurity. Transgenic food crops have been shown to increase food availability and food system security by incorporating ...

  Citation × Citation Citation Abstract Copy Title: Ethical Considerations of Transgenic Biotechnology as a Tool to Address Global Food Insecurity: Implementation and Regulation in Developing Countries Author: Stepper, Shelby Ann Transgenic biotechnology holds enormous potential as a tool to address global food insecurity. Transgenic food crops have been shown to increase food availability and food system security by incorporating disease, pesticide and drought resistance. Production costs of transgenic crops are lower due to the reduced need for costly pesticides and manual tillage, leaving more disposable income for farmers to buy food. Biofortified and nutritionally enriched transgenic crops may be able to reduce vitamin and micronutrient deficiencies. Despite the many promising applications of transgenic food crops in developing countries, many governments have raised major objections to the utilization of transgenic food production and have resisted transgenic crop adoption. The majority of these objections appear to be rooted in societal values, economics related to trade, and ethical principles, not biophysical science. My analysis of the current regulatory system suggests that ethical considerations regarding transgenic food crops are best addressed as part of local regulations rather than incorporated in global trade restrictions. I argue that while there is no silver bullet for solving world hunger, the utilization and responsible regulation of biotechnology could meaningfully contribute its reduction. Title: Ethical Considerations of Transgenic Biotechnology as a Tool to Address Global Food Insecurity: Implementation and Regulation in Developing Countries Author: Stepper, Shelby Ann Transgenic biotechnology holds enormous potential as a tool to address global food insecurity. Transgenic food crops have been shown to increase food availability and food system security by incorporating disease, pesticide and drought resistance. Production costs of transgenic crops are lower due to the reduced need for costly pesticides and manual tillage, leaving more disposable income for farmers to buy food. Biofortified and nutritionally enriched transgenic crops may be able to reduce vitamin and micronutrient deficiencies. Despite the many promising applications of transgenic food crops in developing countries, many governments have raised major objections to the utilization of transgenic food production and have resisted transgenic crop adoption. The majority of these objections appear to be rooted in societal values, economics related to trade, and ethical principles, not biophysical science. My analysis of the current regulatory system suggests that ethical considerations regarding transgenic food crops are best addressed as part of local regulations rather than incorporated in global trade restrictions. I argue that while there is no silver bullet for solving world hunger, the utilization and responsible regulation of biotechnology could meaningfully contribute its reduction. Close

• 73. [Article] Ethanol and High-Value Terpene Co-Production from Lignocellulosic Biomass of Cymbopogon flexuosus and Cymbopogon martinii

  To the best of our knowledge, one or more authors of this paper were federal employees when contributing to this work. This is the publisher’s final pdf. The article was published by the Public Library ...

  Citation × Citation Citation Abstract Copy Title: Ethanol and High-Value Terpene Co-Production from Lignocellulosic Biomass of Cymbopogon flexuosus and Cymbopogon martinii Author: Sykes, Robert, Joyce, Blake L., et al., Zheljazkov, Valtcho D. To the best of our knowledge, one or more authors of this paper were federal employees when contributing to this work. This is the publisher’s final pdf. The article was published by the Public Library of Science and is in the public domain. The published article can be found at: http://www.plosone.org/. Title: Ethanol and High-Value Terpene Co-Production from Lignocellulosic Biomass of Cymbopogon flexuosus and Cymbopogon martinii Author: Sykes, Robert, Joyce, Blake L., et al., Zheljazkov, Valtcho D. To the best of our knowledge, one or more authors of this paper were federal employees when contributing to this work. This is the publisher’s final pdf. The article was published by the Public Library of Science and is in the public domain. The published article can be found at: http://www.plosone.org/. Close

• 74. [Article] Evaporation synergy in a bi-textured soil system

  Evaporation synergy is the phenomenon in which two porous medium textures that share a common vertical boundary experience a higher cumulative evaporation than either homogeneous texture can produce. Studies ...

  Citation × Citation Citation Abstract Copy Title: Evaporation synergy in a bi-textured soil system Author: Fisher, Arthur J. Evaporation synergy is the phenomenon in which two porous medium textures that share a common vertical boundary experience a higher cumulative evaporation than either homogeneous texture can produce. Studies that have been conducted to date address this phenomenon in relatively fine and coarse sands but not in finer textured soils where viscous forces play a major role. The purpose of this study was to determine which of the 66 combinations of soil textures would exhibit evaporation synergy and develop a conceptual model of the conditions necessary for synergy. The numerical modeler HYDRUS was used to investigate all soil texture combinations and generate evaporation rates and cumulative evaporation amounts for each system. In addition, two combinations of soils were selected as laboratory experiments based on the HYDRUS predictions: one that exhibited synergy (Loamy Sand & Silt Loam) and one that did not (Loamy Sand & Sandy Clay). The laboratory data supported the HYDRUS predictions for evaporation synergy and non-synergy. The conditions necessary for evaporation synergy were developed from the numerical and physical models’ predictions and results. The two textures must experience different air-entry values to create lateral and vertical pressure gradients, the fine must possess a high enough hydraulic conductivity to allow water to move to its surface before it reaches its own air-entry value and possess the capillarity to maintain liquid film flow to its surface, and the viscous forces within the coarse must be low enough for water to be pulled from itself to the fine. It was also determined that the evaporation rate of a bi-texture decreases as a series of constant-rate steps until the fine enters S2 evaporation and is associated with a stepwise recession of the drying front in the coarse media. The duration of each step appears to be associated with the lateral distance from which water can be extracted within the coarse media. Title: Evaporation synergy in a bi-textured soil system Author: Fisher, Arthur J. Evaporation synergy is the phenomenon in which two porous medium textures that share a common vertical boundary experience a higher cumulative evaporation than either homogeneous texture can produce. Studies that have been conducted to date address this phenomenon in relatively fine and coarse sands but not in finer textured soils where viscous forces play a major role. The purpose of this study was to determine which of the 66 combinations of soil textures would exhibit evaporation synergy and develop a conceptual model of the conditions necessary for synergy. The numerical modeler HYDRUS was used to investigate all soil texture combinations and generate evaporation rates and cumulative evaporation amounts for each system. In addition, two combinations of soils were selected as laboratory experiments based on the HYDRUS predictions: one that exhibited synergy (Loamy Sand & Silt Loam) and one that did not (Loamy Sand & Sandy Clay). The laboratory data supported the HYDRUS predictions for evaporation synergy and non-synergy. The conditions necessary for evaporation synergy were developed from the numerical and physical models’ predictions and results. The two textures must experience different air-entry values to create lateral and vertical pressure gradients, the fine must possess a high enough hydraulic conductivity to allow water to move to its surface before it reaches its own air-entry value and possess the capillarity to maintain liquid film flow to its surface, and the viscous forces within the coarse must be low enough for water to be pulled from itself to the fine. It was also determined that the evaporation rate of a bi-texture decreases as a series of constant-rate steps until the fine enters S2 evaporation and is associated with a stepwise recession of the drying front in the coarse media. The duration of each step appears to be associated with the lateral distance from which water can be extracted within the coarse media. Close

• 75. [Article] Geostatistical applications to salinity mapping and simulated reclamation

  Geostatistical methods were used to find efficient and accurate means for salinity assessment using regionalized random variables and limited sampling. The random variables selected, sodium absorption ...

  Citation × Citation Citation Abstract Copy Title: Geostatistical applications to salinity mapping and simulated reclamation Author: Al-Taher, Mohamad A. Geostatistical methods were used to find efficient and accurate means for salinity assessment using regionalized random variables and limited sampling. The random variables selected, sodium absorption ratio (SAR), electrical conductivity (EC), and clay content were measured on samples taken over an area of fifteen square miles. Ordinary kriging and co-kriging were used as linear estimators. They were compared on the basis of average kriging variance and sum of squares for error between observed and estimated values. The results indicate a significant improvement in the average kriging variance and sum of squares by using co-kriging estimators. EC was used to estimate SAR because of the high correlation between them. This was not true for clay content. A saving of two-thirds of the cost and time was achieved by using electrical conductivity as an auxiliary variable to estimate sodium absorption ratio. The nonlinear estimator, disjunctive kriging, was an improvement over co-kriging in terms of the variances. More information at the estimation site is a more important consideration than when the estimator is linear. Disjunctive kriging was used to produce an estimate of the conditional probability that the value at an unsampled location is greater than an arbitrary cutoff level. This feature of disjunctive kriging aids salinity assessment and reclamation management. A solute transport model was used to show how saptially variable initial conditions influenced the amount of water required to reclaim a saline soil at each sampling point in a simulated leaching of the area. Title: Geostatistical applications to salinity mapping and simulated reclamation Author: Al-Taher, Mohamad A. Geostatistical methods were used to find efficient and accurate means for salinity assessment using regionalized random variables and limited sampling. The random variables selected, sodium absorption ratio (SAR), electrical conductivity (EC), and clay content were measured on samples taken over an area of fifteen square miles. Ordinary kriging and co-kriging were used as linear estimators. They were compared on the basis of average kriging variance and sum of squares for error between observed and estimated values. The results indicate a significant improvement in the average kriging variance and sum of squares by using co-kriging estimators. EC was used to estimate SAR because of the high correlation between them. This was not true for clay content. A saving of two-thirds of the cost and time was achieved by using electrical conductivity as an auxiliary variable to estimate sodium absorption ratio. The nonlinear estimator, disjunctive kriging, was an improvement over co-kriging in terms of the variances. More information at the estimation site is a more important consideration than when the estimator is linear. Disjunctive kriging was used to produce an estimate of the conditional probability that the value at an unsampled location is greater than an arbitrary cutoff level. This feature of disjunctive kriging aids salinity assessment and reclamation management. A solute transport model was used to show how saptially variable initial conditions influenced the amount of water required to reclaim a saline soil at each sampling point in a simulated leaching of the area. Close

• 76. [Article] Determinants of the Spatial Distribution of Peri-Urban to Rural Agriculture in the United States

  Two issues are focal to the subject of the spatial distribution of crops in peri-urban zones. The first deals with developments in the fields of transportation, other technology, urbanization, and other ...

  Citation × Citation Citation Abstract Copy Title: Determinants of the Spatial Distribution of Peri-Urban to Rural Agriculture in the United States Author: Abdel-Karim, Ibrahim Amin Year: 1987 Two issues are focal to the subject of the spatial distribution of crops in peri-urban zones. The first deals with developments in the fields of transportation, other technology, urbanization, and other factors which are not only prevalent in developed world economies, but which also are thought to force the cultivation of freshly consumed agricultural commodities away from the immediate vicinity of the market center. The second issue pertains to indirectly consumed crops, which are thought to shun proximity to the market center, where land rents per unit area are characteristically high, even when conditions for productions are ideal. Traditional models have shown a zonal pattern of crop distribution in peri-urban areas. The present study sets forth two hypotheses, one pertaining to the spatial distribution of freshly consumed crops, and the other pertaining to the spatial distribution of indirectly consumed crops. It was hypothesized in the present study that freshly consumed crops will continue to be cultivated in the near vicinity of the market center due to characteristics of the crops and the urban market. It was further hypothesized that indirectly consumed crops will continue to be cultivated in the near vicinity of the market center by virtue of greater intensity of production that may be obtained through the use of the environment of designated places. In the case of both crops, the cited factors, as well as others, offset the disadvantages of higher land rent per unit area common to areas close to the market center. These offsetting factors permit agriculture to compete successfully for land in the peri-urban zone. To test these hypotheses, variables were selected to measure the influence that urbanization, transportation, other technologies, the market, the environment, and land use regulations have on agricultural siting patterns in the peri-urban zones of the "Wheat Region" of the central United States. These variables were expressed as equations and were subjected to multiple linear regression (MLR) analysis. The present findings tended to support the research hypotheses. On the basis of these findings, the present research offers a revised model of agricultural cropping patterns, one that reflects the sectoral, rather than the zonal, pattern of crop distribution in peri-urban zones. In the revised model, the mixing of different crops at various locations around the market is feasible, and low-priced grains may compete successfully for high-rent locations in the near vicinity of the urban market. The findings also show that the production of perishable crops in the iIl'.mediate vicinity of the urban market is here to stay, largely due to access to varied means of transportation as well as characteristics of the crops themselves. Furthermore, the findings show that environmental conditions influence the locating of grain production, although economic considerations were seen to supersede them, particularly at high-rent sites. Title: Determinants of the Spatial Distribution of Peri-Urban to Rural Agriculture in the United States Author: Abdel-Karim, Ibrahim Amin Year: 1987 Two issues are focal to the subject of the spatial distribution of crops in peri-urban zones. The first deals with developments in the fields of transportation, other technology, urbanization, and other factors which are not only prevalent in developed world economies, but which also are thought to force the cultivation of freshly consumed agricultural commodities away from the immediate vicinity of the market center. The second issue pertains to indirectly consumed crops, which are thought to shun proximity to the market center, where land rents per unit area are characteristically high, even when conditions for productions are ideal. Traditional models have shown a zonal pattern of crop distribution in peri-urban areas. The present study sets forth two hypotheses, one pertaining to the spatial distribution of freshly consumed crops, and the other pertaining to the spatial distribution of indirectly consumed crops. It was hypothesized in the present study that freshly consumed crops will continue to be cultivated in the near vicinity of the market center due to characteristics of the crops and the urban market. It was further hypothesized that indirectly consumed crops will continue to be cultivated in the near vicinity of the market center by virtue of greater intensity of production that may be obtained through the use of the environment of designated places. In the case of both crops, the cited factors, as well as others, offset the disadvantages of higher land rent per unit area common to areas close to the market center. These offsetting factors permit agriculture to compete successfully for land in the peri-urban zone. To test these hypotheses, variables were selected to measure the influence that urbanization, transportation, other technologies, the market, the environment, and land use regulations have on agricultural siting patterns in the peri-urban zones of the "Wheat Region" of the central United States. These variables were expressed as equations and were subjected to multiple linear regression (MLR) analysis. The present findings tended to support the research hypotheses. On the basis of these findings, the present research offers a revised model of agricultural cropping patterns, one that reflects the sectoral, rather than the zonal, pattern of crop distribution in peri-urban zones. In the revised model, the mixing of different crops at various locations around the market is feasible, and low-priced grains may compete successfully for high-rent locations in the near vicinity of the urban market. The findings also show that the production of perishable crops in the iIl'.mediate vicinity of the urban market is here to stay, largely due to access to varied means of transportation as well as characteristics of the crops themselves. Furthermore, the findings show that environmental conditions influence the locating of grain production, although economic considerations were seen to supersede them, particularly at high-rent sites. Close

• 77. [Article] Interaction of crop plant population with weed competition in corn (Zea mays L.), bush snap beans (Phaseolus vulgaris L.), and onion (Allium cepa L.) at differing stages of development

  Yield reductions due to competition of weeds with crop plants can be extremely important. Early weed competition can be as important in reducing crop yield as weed competition for the entire season. The ...

  Citation × Citation Citation Abstract Copy Title: Interaction of crop plant population with weed competition in corn (Zea mays L.), bush snap beans (Phaseolus vulgaris L.), and onion (Allium cepa L.) at differing stages of development Author: Williams, Clarence Frank Yield reductions due to competition of weeds with crop plants can be extremely important. Early weed competition can be as important in reducing crop yield as weed competition for the entire season. The objectives of this study were (1) to determine the weed control achieved by narrow row-cropping patterns, (2) to measure the competitive effect achieved with narrow row-cropping patterns, with low photosynthetic capacity crop plants or with high photosynthetic capacity plants, in competition with high photosynthetic capacity weeds, (3) to determine at what time weed control becomes important and (4) to determine if the time at which competition begins could be determined by change in weight, sugar content, and/or nitrogen content of the commercial crop. Also, two greenhouse studies were made to evaluate the differential uptake of nitrogen by two competiting species, corn (Zea mays L.) and pigweed (Amaranthus rectroflexus L.), and to evaluate the effect of competition for soil and light between two broadleaf species, snap beans and pigweed. Yields of bush snap beans (Phaseolus vulgaris L.), corn (Zea mays L.), and onion (Allium cepa L.) were all decreased significantly by the presence of weed competition throughout the entire growing season. Reduction in total area occupied by an individual crop plant resulted in decreased effects on vegetative and reproductive parts due to weed competition and increased the effect of crop plant-to-plant competition. Early weed control was important in all crops. In 1969, yield reductions in corn and beans allowed, to compete with weeds for a period of five to six weeks after crop emergence were equal to those from plots with weed competition for the entire season. In 1970, corn required two weeks of cultivation after emergence and snap beans required three weeks of cultivation after emergence to decrease losses due to weed competition. Weed weight yields were significantly reduced in snap beans at the 5 x 5 inch spacing when compared to the 15 x 5 and 35 x 5 inch spacings. As measured by leaf fresh weight, competition was determined to begin between snap beans and redroot pigweed at 36 to 44 days after crop emergence at crop plant spacings of 35 x 5 and 15 x 5 inches. Significant weed competition did not develop after 51 days at crop plant spacings of 5 x 5 inches. Competition between corn and redroot developed 41 days after emergence for all plant spacings. This study indicated the time at which competition between crop and weeds could be determined by leaf fresh weight measurements or by measuring the leaf area of the crop plants. At a fertilizer rate of 77-101-64 pounds of N-P-K per acre, corn made greater gains in total green weight than did pigweed in the greenhouse. However, with the further addition of 300 pounds of ammonium nitrate per acre, pigweed continued to make gains while corn growth was unaffected. At all fertility rates, pigweed had higher levels of total leaf nitrogen than corn. When snap beans had emerged and become established before the emergence of pigweed, the total green and dry weight of pigweed was significantly reduced if growing in full competition or in competition for soil factors only. Title: Interaction of crop plant population with weed competition in corn (Zea mays L.), bush snap beans (Phaseolus vulgaris L.), and onion (Allium cepa L.) at differing stages of development Author: Williams, Clarence Frank Yield reductions due to competition of weeds with crop plants can be extremely important. Early weed competition can be as important in reducing crop yield as weed competition for the entire season. The objectives of this study were (1) to determine the weed control achieved by narrow row-cropping patterns, (2) to measure the competitive effect achieved with narrow row-cropping patterns, with low photosynthetic capacity crop plants or with high photosynthetic capacity plants, in competition with high photosynthetic capacity weeds, (3) to determine at what time weed control becomes important and (4) to determine if the time at which competition begins could be determined by change in weight, sugar content, and/or nitrogen content of the commercial crop. Also, two greenhouse studies were made to evaluate the differential uptake of nitrogen by two competiting species, corn (Zea mays L.) and pigweed (Amaranthus rectroflexus L.), and to evaluate the effect of competition for soil and light between two broadleaf species, snap beans and pigweed. Yields of bush snap beans (Phaseolus vulgaris L.), corn (Zea mays L.), and onion (Allium cepa L.) were all decreased significantly by the presence of weed competition throughout the entire growing season. Reduction in total area occupied by an individual crop plant resulted in decreased effects on vegetative and reproductive parts due to weed competition and increased the effect of crop plant-to-plant competition. Early weed control was important in all crops. In 1969, yield reductions in corn and beans allowed, to compete with weeds for a period of five to six weeks after crop emergence were equal to those from plots with weed competition for the entire season. In 1970, corn required two weeks of cultivation after emergence and snap beans required three weeks of cultivation after emergence to decrease losses due to weed competition. Weed weight yields were significantly reduced in snap beans at the 5 x 5 inch spacing when compared to the 15 x 5 and 35 x 5 inch spacings. As measured by leaf fresh weight, competition was determined to begin between snap beans and redroot pigweed at 36 to 44 days after crop emergence at crop plant spacings of 35 x 5 and 15 x 5 inches. Significant weed competition did not develop after 51 days at crop plant spacings of 5 x 5 inches. Competition between corn and redroot developed 41 days after emergence for all plant spacings. This study indicated the time at which competition between crop and weeds could be determined by leaf fresh weight measurements or by measuring the leaf area of the crop plants. At a fertilizer rate of 77-101-64 pounds of N-P-K per acre, corn made greater gains in total green weight than did pigweed in the greenhouse. However, with the further addition of 300 pounds of ammonium nitrate per acre, pigweed continued to make gains while corn growth was unaffected. At all fertility rates, pigweed had higher levels of total leaf nitrogen than corn. When snap beans had emerged and become established before the emergence of pigweed, the total green and dry weight of pigweed was significantly reduced if growing in full competition or in competition for soil factors only. Close

• 78. [Article] Estimation of genetic-parameters in the Oregon State University Hazelnut (Corylus avellana L.) breeding population

  Heritability in the narrow sense and in the broad sense, variance components and correlation coefficients are important genetic parameters in a breeding program. The estimates of these parameters can provide ...

  Citation × Citation Citation Abstract Copy Title: Estimation of genetic-parameters in the Oregon State University Hazelnut (Corylus avellana L.) breeding population Author: Yao, Qiang Heritability in the narrow sense and in the broad sense, variance components and correlation coefficients are important genetic parameters in a breeding program. The estimates of these parameters can provide important information for a breeder in the selection of parents, the most efficient design for evaluation of seedlings and advanced selections and the choice of selection strategy to improve many target traits simultaneously. In addition, histograms showing the distributions of the traits in offspring may provide additional information about parent combinations for the improvement of target traits. The Oregon State University hazelnut breeding program is developing improved varieties for the kernel market. Estimates of genetic parameters for most traits of interest are not available. Seventy seven trees representing 41 genotypes and 35 progenies were used to investigate midparent values and progeny means for 17 traits, including 13 kernel and nut traits, and 4 phenological traits, for three years. Estimates for heritability in the narrow sense are all high, ranging from 0.56 for amount of kernel fiber, and 0.58 for date of opening of female flowers to 0.87 for percent kernel, 0.88 for nut compression index and 0.89 for nut depth. Therefore, progeny means can be predicted from mid-parent values and response to selection is expected to be rapid for the improvement of all traits. The analysis of variance components revealed that genotypic variance accounted for most of the phenotypic variance. Although significant, the genotype X year interaction only accounted for a very small part of the phenotypic variance. It suggested one year's evaluation of genotypes for all traits should be sufficient except for nut weight, kernel weight, number of nuts per cluster, fiber amount, nut maturity, time of catkin elongation, and time of opening of female flowers. Genetic and phenotypic correlation coeficients were large and positive for nut size traits (nut length, width, depth, nut weight and kernel weight). Phenological traits (date of opening of female flowers, time of catkin elongation and time of leafing out) were also highly and positively correlated. But most other traits were uncorrelated with each other. Therefore, selection of parents with round nuts of medium size, high % kernel, easily-blanched kernels, and early nut maturity is expected to rapidly improve the population for all of these traits. Histograms show that all traits have continuous variation. Transgressive segregation is very common. For all traits except blanching ability, parent combinations may be based on midparent values. For the improvement of blanching ability, both parents should blanch easily. Because existing statistical packages do not allow easy calculation of genetic correlation coefficients for tree fruit and nut crops, the use of a spreadsheet to quickly estimate genetic correlation coefficients is demonstrated. Title: Estimation of genetic-parameters in the Oregon State University Hazelnut (Corylus avellana L.) breeding population Author: Yao, Qiang Heritability in the narrow sense and in the broad sense, variance components and correlation coefficients are important genetic parameters in a breeding program. The estimates of these parameters can provide important information for a breeder in the selection of parents, the most efficient design for evaluation of seedlings and advanced selections and the choice of selection strategy to improve many target traits simultaneously. In addition, histograms showing the distributions of the traits in offspring may provide additional information about parent combinations for the improvement of target traits. The Oregon State University hazelnut breeding program is developing improved varieties for the kernel market. Estimates of genetic parameters for most traits of interest are not available. Seventy seven trees representing 41 genotypes and 35 progenies were used to investigate midparent values and progeny means for 17 traits, including 13 kernel and nut traits, and 4 phenological traits, for three years. Estimates for heritability in the narrow sense are all high, ranging from 0.56 for amount of kernel fiber, and 0.58 for date of opening of female flowers to 0.87 for percent kernel, 0.88 for nut compression index and 0.89 for nut depth. Therefore, progeny means can be predicted from mid-parent values and response to selection is expected to be rapid for the improvement of all traits. The analysis of variance components revealed that genotypic variance accounted for most of the phenotypic variance. Although significant, the genotype X year interaction only accounted for a very small part of the phenotypic variance. It suggested one year's evaluation of genotypes for all traits should be sufficient except for nut weight, kernel weight, number of nuts per cluster, fiber amount, nut maturity, time of catkin elongation, and time of opening of female flowers. Genetic and phenotypic correlation coeficients were large and positive for nut size traits (nut length, width, depth, nut weight and kernel weight). Phenological traits (date of opening of female flowers, time of catkin elongation and time of leafing out) were also highly and positively correlated. But most other traits were uncorrelated with each other. Therefore, selection of parents with round nuts of medium size, high % kernel, easily-blanched kernels, and early nut maturity is expected to rapidly improve the population for all of these traits. Histograms show that all traits have continuous variation. Transgressive segregation is very common. For all traits except blanching ability, parent combinations may be based on midparent values. For the improvement of blanching ability, both parents should blanch easily. Because existing statistical packages do not allow easy calculation of genetic correlation coefficients for tree fruit and nut crops, the use of a spreadsheet to quickly estimate genetic correlation coefficients is demonstrated. Close

• 79. [Article] Biochemical evaluation of silage corn varieties

  Chemical and biological evaluations were conducted to provide chemical composition and digestibility information, in addition to yield data, for silage corn varieties produced on poorly drained Dayton ...

  Citation × Citation Citation Abstract Copy Title: Biochemical evaluation of silage corn varieties Author: Anderson, Daniel Craig Chemical and biological evaluations were conducted to provide chemical composition and digestibility information, in addition to yield data, for silage corn varieties produced on poorly drained Dayton soil series. Each variety was subjected to a Kjeldahl nitrogen, acid detergent fiber, acid detergent lignin, cell wall, and residual ash test. Subsequently cell contents, cellulose, and hemicellulose were calculated by difference. The objectives of this study were to determine if significant differences in nutrient composition and digestibility existed among silage corn varieties grown under similar cultural conditions, and whether such differences could be detected by the detergent analysis scheme in a non-pasture forage. Finally, a comparison of in vitro (artificial rumen) and summative equation digestibility coefficients would indicate the possibility of using the latter for estimating nutritive value in forage crop experimental work. In addition, grass and legume samples, varying widely in nutritive value, were subjected to detergent analysis to ascertain the systems capabilities for assessing differences in chemical composition between forage types. Statistical analysis of the data for chemical composition of the silage corn varieties showed that no significant differences among varieties existed at the five percent probability level. Biological availability of the nutrients of the silage corn varieties was measured by the in vitro (artificial rumen) technique. No significant differences were noted in the 24-hour trials. However, in the 12-hour trials varieties two and four gave coefficients that were significantly (P < .05) greater than varieties one, five, six, seven, or ten. Calculated correlations of the 12 and 24-hour in vitro (artificial rumen) dry matter digestibility and of coefficients estimated by the summative equation were not highly significant. Relationships of chemical constituent data of grass and legume samples from detergent analysis provided evidence that this feed-stuff fractionation accurately reflects differences in chemical composition between species. Hemicellulose values of the grass were four times as great as those of the alfalfa, but the cellulose content was similar for the two forage types. Comparison of silage corn data with that of the alfalfa gave a relationship analogous to that of the alfalfa-grass. Residual ash values of the grass were ten times larger than those of the alfalfa. However, it was not an important factor limiting nutritive value in either the alfalfa or the silage corn. Alfalfa cell wall level and its digestibility were lower than that of the grass. But cell wall material of the grass was twice the amount contained in the alfalfa, and its digestibility was also higher which reflects its lower degree of lignification. Title: Biochemical evaluation of silage corn varieties Author: Anderson, Daniel Craig Chemical and biological evaluations were conducted to provide chemical composition and digestibility information, in addition to yield data, for silage corn varieties produced on poorly drained Dayton soil series. Each variety was subjected to a Kjeldahl nitrogen, acid detergent fiber, acid detergent lignin, cell wall, and residual ash test. Subsequently cell contents, cellulose, and hemicellulose were calculated by difference. The objectives of this study were to determine if significant differences in nutrient composition and digestibility existed among silage corn varieties grown under similar cultural conditions, and whether such differences could be detected by the detergent analysis scheme in a non-pasture forage. Finally, a comparison of in vitro (artificial rumen) and summative equation digestibility coefficients would indicate the possibility of using the latter for estimating nutritive value in forage crop experimental work. In addition, grass and legume samples, varying widely in nutritive value, were subjected to detergent analysis to ascertain the systems capabilities for assessing differences in chemical composition between forage types. Statistical analysis of the data for chemical composition of the silage corn varieties showed that no significant differences among varieties existed at the five percent probability level. Biological availability of the nutrients of the silage corn varieties was measured by the in vitro (artificial rumen) technique. No significant differences were noted in the 24-hour trials. However, in the 12-hour trials varieties two and four gave coefficients that were significantly (P < .05) greater than varieties one, five, six, seven, or ten. Calculated correlations of the 12 and 24-hour in vitro (artificial rumen) dry matter digestibility and of coefficients estimated by the summative equation were not highly significant. Relationships of chemical constituent data of grass and legume samples from detergent analysis provided evidence that this feed-stuff fractionation accurately reflects differences in chemical composition between species. Hemicellulose values of the grass were four times as great as those of the alfalfa, but the cellulose content was similar for the two forage types. Comparison of silage corn data with that of the alfalfa gave a relationship analogous to that of the alfalfa-grass. Residual ash values of the grass were ten times larger than those of the alfalfa. However, it was not an important factor limiting nutritive value in either the alfalfa or the silage corn. Alfalfa cell wall level and its digestibility were lower than that of the grass. But cell wall material of the grass was twice the amount contained in the alfalfa, and its digestibility was also higher which reflects its lower degree of lignification. Close

• 80. [Article] Combining ability and associations of agronomic traits involving three sources of dwarfism in wheat (Triticum aestivum, L. em Thell)

  Three genetically different dwarf cultivars of spring wheat were evaluated as potential sources of short stature to use in a wheat improvement program. The study involved a five parent diallel cross which ...

  Citation × Citation Citation Abstract Copy Title: Combining ability and associations of agronomic traits involving three sources of dwarfism in wheat (Triticum aestivum, L. em Thell) Author: Maya de Leon, Jose Luis Three genetically different dwarf cultivars of spring wheat were evaluated as potential sources of short stature to use in a wheat improvement program. The study involved a five parent diallel cross which included a semidwarf, a standard height and three dwarf cultivars. The genetic sources of dwarfism included a Norma 10 derivative named Vicam 71, a derived line from Tom Thumb called Tordo, and Olesen dwarf. Experimental material consisted of parental lines, F₁, F₂, and both backcrosses to the parents space planted in a randomized block design. The agronomic characters measured on an individual plant basis were: (1) plant height, (2) days to heading, (3) number of tillers, (4) number of spikelets per spike, (5) head length, (6) days to maturity, (7) grain yield, (8) harvest index, (9) kernel weight, (10) number of kernels per spikelet, (11) rachis internode length, (12) grain filling period and, (13) head grain weight. Estimates of gene action were determined by heterosis, heterobeltiosis, broad and narrow sense heritabilities and combining ability analyses. Associations among traits were estimated by phenotypic, environmental, and genotypic correlations as well as path-coefficient analysis for grain yield and eight of the variables. There were significant differences among the parental lines, their crosses, and generations for all traits measured. Either partial dominance for tallness or no dominance was manifested for those crosses involving the dwarf cultivars Vicam 71 and Olesen. Tordo, when crossed to taller wheats showed dominance for short stature. All three genetic sources of dwarfism and their resulting progenies manifested desirable agronomic characteristics. Vicam 71 was a good parent in terms of grain yield and number of tillers per plant. Tordo was the best source for increasing the number of spikelets per spike, kernel weight and head grain weight. Olesen was a good progenitor for increasing number of kernels per spikelet. All three dwarf cultivars displayed some advantage(s) over the other two and all could be used to breed short statured wheats with a possibility of success. Plant height did not appear to have a direct effect on plant grain yield in any of the 10 crosses. With the exception of number of tillers per plant and grain yield, a major proportion of the phenotypic variability observed for all characters studied was due to genetic factors. A large portion of the total genetic variability associated with days to heading, maturity, height, rachis internode, spikelet number, kernels per spikelet, kernel weight, and harvest index was mainly a result of additive gene action. Both additive and non-additive genetic effects were involved in the expression of grain filling period and head weight. The nonadditive portion of the genetic variance associated with tiller number and grain yield per plant was relatively large when compared with the additive portion. Therefore, selection for increased expression of tillers and yield should be delayed until the F₄ or later generations where a large degree of homozygosity has been obtained. The genetic correlations for individual crosses indicated that only a few of the traits studied were associated in the same manner in most or all the 10 hybridizations. High positive genetic correlations were found between plant grain yield vs tiller number and kernels per spikelet, tiller number vs days to maturity, kernels per spikelet vs head grain weight, plant height vs head weight, and head length vs rachis internode length. High negative genetic correlations were found between kernel weight vs days to maturity, plant height vs harvest index, and days to heading vs grain filling period. Most correlations among agronomic traits were different in value and/or sign from one cross to another suggesting different gene associations in the parental cultivars. Genetic correlations between components of yield showed this type of inconsistency. Therefore, grain yield could be increased by a combined increase of more than one component of yield without compensatory oscillation among them because tiller number, spikelet number, kernels per spikelet and kernel weight were often not correlated between one another and sometimes were positively correlated. Path-coefficients analysis indicated that number of tiller per plant had a high direct effect on grain yield in all crosses. With the exception of two crosses, indirect effects of this trait were negligible. In the latter two crosses tiller number had a high negative indirect effect on plant grain yield via head grain weight. Kernels per spikelet and kernel weight had no direct effects on grain yield but their indirect effects via head weight were positive and significant. Large amounts of additive gene action were observed in the expression of plant height. This trait was also highly negatively correlated with harvest index; therefore, phenotypic selection for restricted plant height would be useful in obtaining lines with high grain to straw ratios. In general, crosses that showed high specific combining ability effects involved parents with low general combining ability. However, there were some exceptions to this rule. Crosses of high x high and high x low general combiners presented high specific combining ability effects, suggesting that some additive gene action may be involved in the superior performance of these combinations. Also the F ₂ generation did not differ from the F₁ in assessing general cornbining ability. A wheat breeder should be aware of those genetic associations between agronomic traits that could be used to select superior cultivars. However, the genetic correlations in this study suggested that each cross represented a different set of gene associations depending upon the parents involved. If some progress is to be made in using the genetic variability available in the crop, the breeder should not try to select exactly the same type of plant from every cross. Every hybridization is potentially a source of better lines if they are well planned and the reasons they were made are remembered during selection. It is very important to realize what are the contributions of each parental line in a cross and what are the most important trait associations present in each parent. Superior rural genetic variability existing in the crop. Title: Combining ability and associations of agronomic traits involving three sources of dwarfism in wheat (Triticum aestivum, L. em Thell) Author: Maya de Leon, Jose Luis Three genetically different dwarf cultivars of spring wheat were evaluated as potential sources of short stature to use in a wheat improvement program. The study involved a five parent diallel cross which included a semidwarf, a standard height and three dwarf cultivars. The genetic sources of dwarfism included a Norma 10 derivative named Vicam 71, a derived line from Tom Thumb called Tordo, and Olesen dwarf. Experimental material consisted of parental lines, F₁, F₂, and both backcrosses to the parents space planted in a randomized block design. The agronomic characters measured on an individual plant basis were: (1) plant height, (2) days to heading, (3) number of tillers, (4) number of spikelets per spike, (5) head length, (6) days to maturity, (7) grain yield, (8) harvest index, (9) kernel weight, (10) number of kernels per spikelet, (11) rachis internode length, (12) grain filling period and, (13) head grain weight. Estimates of gene action were determined by heterosis, heterobeltiosis, broad and narrow sense heritabilities and combining ability analyses. Associations among traits were estimated by phenotypic, environmental, and genotypic correlations as well as path-coefficient analysis for grain yield and eight of the variables. There were significant differences among the parental lines, their crosses, and generations for all traits measured. Either partial dominance for tallness or no dominance was manifested for those crosses involving the dwarf cultivars Vicam 71 and Olesen. Tordo, when crossed to taller wheats showed dominance for short stature. All three genetic sources of dwarfism and their resulting progenies manifested desirable agronomic characteristics. Vicam 71 was a good parent in terms of grain yield and number of tillers per plant. Tordo was the best source for increasing the number of spikelets per spike, kernel weight and head grain weight. Olesen was a good progenitor for increasing number of kernels per spikelet. All three dwarf cultivars displayed some advantage(s) over the other two and all could be used to breed short statured wheats with a possibility of success. Plant height did not appear to have a direct effect on plant grain yield in any of the 10 crosses. With the exception of number of tillers per plant and grain yield, a major proportion of the phenotypic variability observed for all characters studied was due to genetic factors. A large portion of the total genetic variability associated with days to heading, maturity, height, rachis internode, spikelet number, kernels per spikelet, kernel weight, and harvest index was mainly a result of additive gene action. Both additive and non-additive genetic effects were involved in the expression of grain filling period and head weight. The nonadditive portion of the genetic variance associated with tiller number and grain yield per plant was relatively large when compared with the additive portion. Therefore, selection for increased expression of tillers and yield should be delayed until the F₄ or later generations where a large degree of homozygosity has been obtained. The genetic correlations for individual crosses indicated that only a few of the traits studied were associated in the same manner in most or all the 10 hybridizations. High positive genetic correlations were found between plant grain yield vs tiller number and kernels per spikelet, tiller number vs days to maturity, kernels per spikelet vs head grain weight, plant height vs head weight, and head length vs rachis internode length. High negative genetic correlations were found between kernel weight vs days to maturity, plant height vs harvest index, and days to heading vs grain filling period. Most correlations among agronomic traits were different in value and/or sign from one cross to another suggesting different gene associations in the parental cultivars. Genetic correlations between components of yield showed this type of inconsistency. Therefore, grain yield could be increased by a combined increase of more than one component of yield without compensatory oscillation among them because tiller number, spikelet number, kernels per spikelet and kernel weight were often not correlated between one another and sometimes were positively correlated. Path-coefficients analysis indicated that number of tiller per plant had a high direct effect on grain yield in all crosses. With the exception of two crosses, indirect effects of this trait were negligible. In the latter two crosses tiller number had a high negative indirect effect on plant grain yield via head grain weight. Kernels per spikelet and kernel weight had no direct effects on grain yield but their indirect effects via head weight were positive and significant. Large amounts of additive gene action were observed in the expression of plant height. This trait was also highly negatively correlated with harvest index; therefore, phenotypic selection for restricted plant height would be useful in obtaining lines with high grain to straw ratios. In general, crosses that showed high specific combining ability effects involved parents with low general combining ability. However, there were some exceptions to this rule. Crosses of high x high and high x low general combiners presented high specific combining ability effects, suggesting that some additive gene action may be involved in the superior performance of these combinations. Also the F ₂ generation did not differ from the F₁ in assessing general cornbining ability. A wheat breeder should be aware of those genetic associations between agronomic traits that could be used to select superior cultivars. However, the genetic correlations in this study suggested that each cross represented a different set of gene associations depending upon the parents involved. If some progress is to be made in using the genetic variability available in the crop, the breeder should not try to select exactly the same type of plant from every cross. Every hybridization is potentially a source of better lines if they are well planned and the reasons they were made are remembered during selection. It is very important to realize what are the contributions of each parental line in a cross and what are the most important trait associations present in each parent. Superior rural genetic variability existing in the crop. Close