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• 11. [Article] Nature of inheritance and association of time, duration and rate of grain filling and subsequent grain yield in crosses of winter and spring wheats (Triticum aestivum L. em Thell)

  The nature of inheritance and possible associations for traits influencing earliness and grain yield were investigated using a four parent diallel of winter and spring wheat cultivars. More genetic variability ...

  Citation × Citation Citation Abstract Copy Title: Nature of inheritance and association of time, duration and rate of grain filling and subsequent grain yield in crosses of winter and spring wheats (Triticum aestivum L. em Thell) Author: Choi, Byung Han The nature of inheritance and possible associations for traits influencing earliness and grain yield were investigated using a four parent diallel of winter and spring wheat cultivars. More genetic variability was observed for the traits measured in segregating populations resulting from crosses between winter and spring type wheats in contrast to spring x spring or winter x winter crosses. The one exception was plant height where more genetic variability resulted from spring x spring crosses. Narrow sense heritability estimates were high for time and duration of heading, anthesis, grain filling and physiological maturity and for plant height. Smaller values were noted for rate of grain filling, kernel number, harvest index, tiller number, kernel weight, whole plant dry weight and grain yield. Estimates of the coefficient of heritability and the parent-offspring correlation coefficient were similar in magnitude except for the traits grain yield, tiller number, kernel weight and whole plant dry weight where large variations due to the environment were encountered. Using the Jinks-Hayman model, no maternal effects were noted nor were any nonallelic interactions observed for total duration of grain filling and lag period. The actual grain filling period was influenced to some degree by such interactions. The spring cultivars also appeared to have more dominant genes for longer total duration of grain filling and lag period. In contrast the winter parents had more dominant genes for the longer actual grain filling period. Estimates of general and specific combining ability provided similar evidence in terms of the nature of gene action. Both additive and nonadditive gene action was present for all traits, the relative magnitudes depending on the specific trait. Based on individual combining ability effects, the winter x spring cross Yamhill x Siete Cerros would appear to provide the highest proportion of desired segregates when combining earliness and acceptable grain yield. From the direct and indirect associations of grain yield, it would appear that a shorter duration of grain filling along with a shorter lag period from heading to anthesis are important for higher rates of grain filling if negative associations between earliness and grain yield are to be avoided. Title: Nature of inheritance and association of time, duration and rate of grain filling and subsequent grain yield in crosses of winter and spring wheats (Triticum aestivum L. em Thell) Author: Choi, Byung Han The nature of inheritance and possible associations for traits influencing earliness and grain yield were investigated using a four parent diallel of winter and spring wheat cultivars. More genetic variability was observed for the traits measured in segregating populations resulting from crosses between winter and spring type wheats in contrast to spring x spring or winter x winter crosses. The one exception was plant height where more genetic variability resulted from spring x spring crosses. Narrow sense heritability estimates were high for time and duration of heading, anthesis, grain filling and physiological maturity and for plant height. Smaller values were noted for rate of grain filling, kernel number, harvest index, tiller number, kernel weight, whole plant dry weight and grain yield. Estimates of the coefficient of heritability and the parent-offspring correlation coefficient were similar in magnitude except for the traits grain yield, tiller number, kernel weight and whole plant dry weight where large variations due to the environment were encountered. Using the Jinks-Hayman model, no maternal effects were noted nor were any nonallelic interactions observed for total duration of grain filling and lag period. The actual grain filling period was influenced to some degree by such interactions. The spring cultivars also appeared to have more dominant genes for longer total duration of grain filling and lag period. In contrast the winter parents had more dominant genes for the longer actual grain filling period. Estimates of general and specific combining ability provided similar evidence in terms of the nature of gene action. Both additive and nonadditive gene action was present for all traits, the relative magnitudes depending on the specific trait. Based on individual combining ability effects, the winter x spring cross Yamhill x Siete Cerros would appear to provide the highest proportion of desired segregates when combining earliness and acceptable grain yield. From the direct and indirect associations of grain yield, it would appear that a shorter duration of grain filling along with a shorter lag period from heading to anthesis are important for higher rates of grain filling if negative associations between earliness and grain yield are to be avoided. Close

• 12. [Article] Effects of irrigation frequency on yields of winter wheat

  Deliberately underirrigating a crop may yield economic benefits. The optimal use of water by an irrigator should be achieved under a deficit irrigation regime. It is important to know how water deficits ...

  Citation × Citation Citation Abstract Copy Title: Effects of irrigation frequency on yields of winter wheat Author: Nakamura, Brian Clifford Deliberately underirrigating a crop may yield economic benefits. The optimal use of water by an irrigator should be achieved under a deficit irrigation regime. It is important to know how water deficits affect yields and the interaction of the deficits with the scheduling of irrigations. A field experiment was conducted during the 1981 irrigation season to investigate the effects of high and low frequency deficit irrigation on yields of winter wheat. Yield and water use data were used to construct three production functions. The relationship between the level of water use and the resulting yield were determined for three irrigation frequency regimes. Field plots under daily (high frequency), weekly (normal frequency), and stress (reduced frequency) regimes were included in the field experiment as well as two dryland production plots. The relationships derived from this project were characterized by a large degree of scatter in the results. Highly favorable weather conditions offset the effects of irrigation deficits on plant yields throughout the irrigation season. At this time, a second year of data is in the process of compilation. The results of a regression analysis showed no statistically significant difference in the water use-yield relationships of the three irrigation frequency regimes. The effect of frequency did not lead to any readily apparent differences in the three production functions. The efficiency of water use of the different irrigation frequencies increases with decreasing amount of applied water for the 1981 crop year. The most efficient treatment, i.e., least water use per unit of yield, was the pre-plant irrigated, dryfarmed plots. The density of the wheat, a measure of crop quality also increased with decreased water use in this experiment. The optimal irrigation treatment (measured by production and quality) was the two-week frequency set. Title: Effects of irrigation frequency on yields of winter wheat Author: Nakamura, Brian Clifford Deliberately underirrigating a crop may yield economic benefits. The optimal use of water by an irrigator should be achieved under a deficit irrigation regime. It is important to know how water deficits affect yields and the interaction of the deficits with the scheduling of irrigations. A field experiment was conducted during the 1981 irrigation season to investigate the effects of high and low frequency deficit irrigation on yields of winter wheat. Yield and water use data were used to construct three production functions. The relationship between the level of water use and the resulting yield were determined for three irrigation frequency regimes. Field plots under daily (high frequency), weekly (normal frequency), and stress (reduced frequency) regimes were included in the field experiment as well as two dryland production plots. The relationships derived from this project were characterized by a large degree of scatter in the results. Highly favorable weather conditions offset the effects of irrigation deficits on plant yields throughout the irrigation season. At this time, a second year of data is in the process of compilation. The results of a regression analysis showed no statistically significant difference in the water use-yield relationships of the three irrigation frequency regimes. The effect of frequency did not lead to any readily apparent differences in the three production functions. The efficiency of water use of the different irrigation frequencies increases with decreasing amount of applied water for the 1981 crop year. The most efficient treatment, i.e., least water use per unit of yield, was the pre-plant irrigated, dryfarmed plots. The density of the wheat, a measure of crop quality also increased with decreased water use in this experiment. The optimal irrigation treatment (measured by production and quality) was the two-week frequency set. Close

• 13. [Article] The need to breed crop varieties suitable for organic farming using wheat, tomato and broccoli as examples: A review

  This is the author's peer-reviewed final manuscript, as accepted by the publisher. The article is copyrighted by the Royal Netherlands Society for Agricultural Sciences and published by Elsevier. It can ...

  Citation × Citation Citation Abstract Copy Title: The need to breed crop varieties suitable for organic farming using wheat, tomato and broccoli as examples: A review Author: Leifert, C., Myers, J. R., Lammerts van Bueren, E. T., Messmer, M. M., Murphy, K. M., Jones, S. S., Tamm, L. This is the author's peer-reviewed final manuscript, as accepted by the publisher. The article is copyrighted by the Royal Netherlands Society for Agricultural Sciences and published by Elsevier. It can be found at: http://www.journals.elsevier.com/njas-wageningen-journal-of-life-sciences/. Title: The need to breed crop varieties suitable for organic farming using wheat, tomato and broccoli as examples: A review Author: Leifert, C., Myers, J. R., Lammerts van Bueren, E. T., Messmer, M. M., Murphy, K. M., Jones, S. S., Tamm, L. This is the author's peer-reviewed final manuscript, as accepted by the publisher. The article is copyrighted by the Royal Netherlands Society for Agricultural Sciences and published by Elsevier. It can be found at: http://www.journals.elsevier.com/njas-wageningen-journal-of-life-sciences/. Close

• 14. [Article] Remote-sensing and geographic information system techniques to map spatial variation of wheat grain yield

  Farmers and researchers are aware of spatial variation in grain yield within farms or fields. Fertilizer management may be improved if techniques can be developed to identify grain yield variations in ...

  Citation × Citation Citation Abstract Copy Title: Remote-sensing and geographic information system techniques to map spatial variation of wheat grain yield Author: Roberts, Michael C. (Michael Coy), 1951- Farmers and researchers are aware of spatial variation in grain yield within farms or fields. Fertilizer management may be improved if techniques can be developed to identify grain yield variations in wheat fields. Aerial color infrared (CIR) photography was used to identify winter wheat (Triticum aestivum L.) canopy biomass variability in the Spring of the growing season. Low yielding areas identified from CIR photography were associated with shallow soil profiles consistent with soil forming factors of the region, and were significantly different from average and high yielding areas. The high yielding areas were located within a few meters of a drainage way, and were not significantly different than the average yielding areas except in one field with a deep soil profile and low variance. Fields with heterogeneous CIR photographs had high variances because of many dissimilar inclusions. CIR photography, although useful to distinguish vegetational differences, requires complex timing, ground verification, and correction to estimate yield variability. A geographic information system (GIS) was used to overlay photo interpreted biomass and soil map units. The overlay analysis allowed construction of a higher (first) order soil map indicating inclusions. Area calculation of the inclusions and map units using a GIS function combined with estimated yield (no variance estimates or confidence intervals associated with the estimated yield) data suggests fertilizer management with a first order soil map to increase fertilizer efficiency by up to six percent. Future research combining remotely-sensed subsidiary variables correlated with moisture supply capacity estimates from soil survey methods may assess, using relatively new spatially dependent interpolation methods, the local and regional variation in wheat grain yield. Title: Remote-sensing and geographic information system techniques to map spatial variation of wheat grain yield Author: Roberts, Michael C. (Michael Coy), 1951- Farmers and researchers are aware of spatial variation in grain yield within farms or fields. Fertilizer management may be improved if techniques can be developed to identify grain yield variations in wheat fields. Aerial color infrared (CIR) photography was used to identify winter wheat (Triticum aestivum L.) canopy biomass variability in the Spring of the growing season. Low yielding areas identified from CIR photography were associated with shallow soil profiles consistent with soil forming factors of the region, and were significantly different from average and high yielding areas. The high yielding areas were located within a few meters of a drainage way, and were not significantly different than the average yielding areas except in one field with a deep soil profile and low variance. Fields with heterogeneous CIR photographs had high variances because of many dissimilar inclusions. CIR photography, although useful to distinguish vegetational differences, requires complex timing, ground verification, and correction to estimate yield variability. A geographic information system (GIS) was used to overlay photo interpreted biomass and soil map units. The overlay analysis allowed construction of a higher (first) order soil map indicating inclusions. Area calculation of the inclusions and map units using a GIS function combined with estimated yield (no variance estimates or confidence intervals associated with the estimated yield) data suggests fertilizer management with a first order soil map to increase fertilizer efficiency by up to six percent. Future research combining remotely-sensed subsidiary variables correlated with moisture supply capacity estimates from soil survey methods may assess, using relatively new spatially dependent interpolation methods, the local and regional variation in wheat grain yield. Close

• 15. [Article] The effect of seeding rate on yield and yield components of two winter wheat varieties

  Wheat is an important cereal crop in the Willamette Valley of Oregon and the stiff-strawed, high-yielding varieties are the predominant types grown. Observation of the effect of seeding rates on the yield ...

  Citation × Citation Citation Abstract Copy Title: The effect of seeding rate on yield and yield components of two winter wheat varieties Author: Rana, Prakriti Shumshere Jung Bahadur Wheat is an important cereal crop in the Willamette Valley of Oregon and the stiff-strawed, high-yielding varieties are the predominant types grown. Observation of the effect of seeding rates on the yield and yield components are useful in determining which of the components contributes most to the yield of a winter wheat variety and in developing optimum seeding rate recommendations. The experiments were conducted in 1963-1964, 1964-1965, and 1965-1966. The purpose of these studies was to determine the effect of various seeding rates on the yield and yield components of two winter wheat varieties and to find the optimum seeding rates for these varieties. A further objective was to determine if reasonable yields could be obtained from low rates of seeding for both varieties. The yield was measured in terms of bushels per acre. The yield components studied were (1) the number of spikes per unit area, (2) number of spikelets per spike, (3) number of kernels per spike, and (4) the weight of 100 kernels. The results were obtained and comparisons were made between the two varieties and their performance over a three-year period. There was considerable fluctuation in the yields involving both varieties for all seeding rates in the different seasons. The 1966 season was most favorable for Gaines and the 1964 season for Druchamp. Druchamp gave higher yields than Gaines for all seeding rates. The number of spikes per unit area for both varieties was most effected by differences in seeding rate in each year, while the other components showed no response. High yield of Druchamp was due to the result of more spikes per unit area, heavy kernels, and resistance to stripe rust. The yield of Gaines was the result of more kernels per spike. The higher seeding rates for both varieties produced the highest yields. Title: The effect of seeding rate on yield and yield components of two winter wheat varieties Author: Rana, Prakriti Shumshere Jung Bahadur Wheat is an important cereal crop in the Willamette Valley of Oregon and the stiff-strawed, high-yielding varieties are the predominant types grown. Observation of the effect of seeding rates on the yield and yield components are useful in determining which of the components contributes most to the yield of a winter wheat variety and in developing optimum seeding rate recommendations. The experiments were conducted in 1963-1964, 1964-1965, and 1965-1966. The purpose of these studies was to determine the effect of various seeding rates on the yield and yield components of two winter wheat varieties and to find the optimum seeding rates for these varieties. A further objective was to determine if reasonable yields could be obtained from low rates of seeding for both varieties. The yield was measured in terms of bushels per acre. The yield components studied were (1) the number of spikes per unit area, (2) number of spikelets per spike, (3) number of kernels per spike, and (4) the weight of 100 kernels. The results were obtained and comparisons were made between the two varieties and their performance over a three-year period. There was considerable fluctuation in the yields involving both varieties for all seeding rates in the different seasons. The 1966 season was most favorable for Gaines and the 1964 season for Druchamp. Druchamp gave higher yields than Gaines for all seeding rates. The number of spikes per unit area for both varieties was most effected by differences in seeding rate in each year, while the other components showed no response. High yield of Druchamp was due to the result of more spikes per unit area, heavy kernels, and resistance to stripe rust. The yield of Gaines was the result of more kernels per spike. The higher seeding rates for both varieties produced the highest yields. Close

• 16. [Article] Adaptability of winter wheat cultivars to dryland conditions and their response to water stress

  Winter wheat cultivars (Triticum aestivum) were evaluated for their response to water stress and adaptability to a wide range of moisture limited environments. Grain yield was analyzed for ten cultivars ...

  Citation × Citation Citation Abstract Copy Title: Adaptability of winter wheat cultivars to dryland conditions and their response to water stress Author: Keim, Don Lee Winter wheat cultivars (Triticum aestivum) were evaluated for their response to water stress and adaptability to a wide range of moisture limited environments. Grain yield was analyzed for ten cultivars at six locations across four years. Regression of the cultivar mean on the year-location mean was used as a measure of the environmental response of a particular cultivar, Plant water status (leaf osmotic potential and water potential) during the grain filling period, along with grain yield and yield components were determined at three locations for fifteen cultivars under space-planted conditions in 1972 and for ten cultivars under solid-seeding in 1973. Five cultivars were evaluated for plant water status and rates of growth during reproductive development and for final grain yield and yield components at a severely stressed location in 1973. Drought resistance, described as yielding ability under severe soil moisture stress, was found to be the result of avoidance, tolerance and escape characteristics. Plant water status influenced the components of yield when their development occurred during a period of high external stress. However, the relative importance of plant water status to final yield varied depending on the magnitude of the direct effect of spike number on yield. Drought avoidance was the ability to maintain a high plant water status when under high external stress conditions. In the cultivar Yamhill, the stable growth rate during inflorescence development and the extended period of grain filling may have resulted from the ability of this cultivar to avoid drought. These characteristics, also, may explain the large spikelet number and the high kernel weight of Yamhill. Even though Hyslop and Wanser had a moderate and high internal water stress, respectively, they were relatively tolerant of stress in terms of high growth rates during the grain filling period. The high yielding ability of Wanser and McDermid under high stress conditions was primarily related to a large number of spikes. This trait was considered an escape characteristic because tillering was established before the onset of severe stress. The club wheats neither avoided or tolerated internal water stress under solid-seeded conditions nor did they have sufficient tillering capacity to compensate for the effect of stress on the laterdeveloped components.of yield. Nugaines, Hyslop and Rew maintained a moderate internal stress during later development but differed in their yield component responses. The yield of Nugaines depended primarily on a high tillering capacity, whereas the yield of Hyslop and Rew depended on a balance of contributions from all the components of yield. Widely adapted cultivars, such as Hyslop and McDermid, not only yielded well under severe stress conditions but had the genetic potential to respond adequately to more favorable moisture conditions. Cultivars specifically, adapted to lower yielding environments, such as Yamhill and Wanser, were able to avoid, tolerate or escape drought but were limited in one or more of their yield component responses to better conditions. Conversely, cultivars specifically adapted to high yielding environments, such as Nugaines and Paha, lacked the ability to consistently yield well under high stress environments but had a high response to more favorable moisture conditions. Cultivars best adapted to dryland cultivation should have the highest yield under stress conditions as expressed through the components of yield by one or a combination of avoidance, tolerance or escape characteristics. These cultivars should also have the maximum expression in, and balance among, the components of yield for maximum response to more favorable moisture conditions. This goal may be obtained by selection in favorable as well as stressed environments and by testing throughout the range of the environments where the cultivar is expected to be grown. Because high yield under stress was found in this study to be manifested through different characteristics of the plant the breeder should be aware of traits which may contribute to drought resistance, but he should not be restricted to a particular ideotype when breeding for yield under conditions of high moisture stress. Title: Adaptability of winter wheat cultivars to dryland conditions and their response to water stress Author: Keim, Don Lee Winter wheat cultivars (Triticum aestivum) were evaluated for their response to water stress and adaptability to a wide range of moisture limited environments. Grain yield was analyzed for ten cultivars at six locations across four years. Regression of the cultivar mean on the year-location mean was used as a measure of the environmental response of a particular cultivar, Plant water status (leaf osmotic potential and water potential) during the grain filling period, along with grain yield and yield components were determined at three locations for fifteen cultivars under space-planted conditions in 1972 and for ten cultivars under solid-seeding in 1973. Five cultivars were evaluated for plant water status and rates of growth during reproductive development and for final grain yield and yield components at a severely stressed location in 1973. Drought resistance, described as yielding ability under severe soil moisture stress, was found to be the result of avoidance, tolerance and escape characteristics. Plant water status influenced the components of yield when their development occurred during a period of high external stress. However, the relative importance of plant water status to final yield varied depending on the magnitude of the direct effect of spike number on yield. Drought avoidance was the ability to maintain a high plant water status when under high external stress conditions. In the cultivar Yamhill, the stable growth rate during inflorescence development and the extended period of grain filling may have resulted from the ability of this cultivar to avoid drought. These characteristics, also, may explain the large spikelet number and the high kernel weight of Yamhill. Even though Hyslop and Wanser had a moderate and high internal water stress, respectively, they were relatively tolerant of stress in terms of high growth rates during the grain filling period. The high yielding ability of Wanser and McDermid under high stress conditions was primarily related to a large number of spikes. This trait was considered an escape characteristic because tillering was established before the onset of severe stress. The club wheats neither avoided or tolerated internal water stress under solid-seeded conditions nor did they have sufficient tillering capacity to compensate for the effect of stress on the laterdeveloped components.of yield. Nugaines, Hyslop and Rew maintained a moderate internal stress during later development but differed in their yield component responses. The yield of Nugaines depended primarily on a high tillering capacity, whereas the yield of Hyslop and Rew depended on a balance of contributions from all the components of yield. Widely adapted cultivars, such as Hyslop and McDermid, not only yielded well under severe stress conditions but had the genetic potential to respond adequately to more favorable moisture conditions. Cultivars specifically, adapted to lower yielding environments, such as Yamhill and Wanser, were able to avoid, tolerate or escape drought but were limited in one or more of their yield component responses to better conditions. Conversely, cultivars specifically adapted to high yielding environments, such as Nugaines and Paha, lacked the ability to consistently yield well under high stress environments but had a high response to more favorable moisture conditions. Cultivars best adapted to dryland cultivation should have the highest yield under stress conditions as expressed through the components of yield by one or a combination of avoidance, tolerance or escape characteristics. These cultivars should also have the maximum expression in, and balance among, the components of yield for maximum response to more favorable moisture conditions. This goal may be obtained by selection in favorable as well as stressed environments and by testing throughout the range of the environments where the cultivar is expected to be grown. Because high yield under stress was found in this study to be manifested through different characteristics of the plant the breeder should be aware of traits which may contribute to drought resistance, but he should not be restricted to a particular ideotype when breeding for yield under conditions of high moisture stress. Close

• 17. [Article] Estimates of heterosis for five agronomic traits in selected winter x spring and winter x winter wheat crosses (Triticum aestivum L. em Thell)

  Concern regarding the lack of genetic variability and the apparent yield plateau reached in wheat breeding have prompted this investigation. The systematic crossing of spring and winter wheat types which ...

  Citation × Citation Citation Abstract Copy Title: Estimates of heterosis for five agronomic traits in selected winter x spring and winter x winter wheat crosses (Triticum aestivum L. em Thell) Author: Brajcich, P. Concern regarding the lack of genetic variability and the apparent yield plateau reached in wheat breeding have prompted this investigation. The systematic crossing of spring and winter wheat types which have evolved to form somewhat different gene pools, may provide a source of additional usable genetic variability for future yield increases. Five winter and five spring wheat cultivars with different degrees of genetic similarities in their pedigrees were crossed to obtain F1's and F2's. The parents plus winter x spring F1's were planted in two growing seasons at Hyslop Agronomy Farm near Corvallis, Oregon. During the second season the winter x spring F2 and winter x winter F1 crosses were also included. Agronomic traits were measured on an individual plant basis. These traits were plant height, number of tillers per plant, 100 kernel weight, number of kernels per spike and grain yield. Analyses of variance were conducted for each trait. Estimates of the amount of usable genetic variation were determined by heterosis values, inbreeding depression and parent-progeny standard regressions. Possible interactions between years and the above five characters were determined for the winter x spring F1's. Evidence of non-additive gene action was found in the expression of heterosis and subsequent inbreeding depression which depended on the specific trait measured and the parents involved in the cross. The greatest heterosis values were noted for grain yield per plant. Crosses with the winter parent, Weique Red Mace, resulted in the highest estimates for grain yield. This was due to the late maturity of these hybrids and to the diverse genetic background of this winter parent compared to the five spring parents. Parent-progeny regressions indicated that a large amount of additive genetic variance was present for plant height, 100 kernel weight and grain yield an intermediate amount for kernels per spike and tillers per plant. Winter x spring F1 crosses resulted in higher heterosis estimates and a wider range of values between crosses than winter x winter F1 crosses. Parent-progeny regression estimates were similar in value for the two types of F1 populations. Thus, these results indicate that the systematic crossing between winter and spring wheats will produce greater total genetic variability for further wheat improvement. This is true for the development of hybrid wheat (non-additive) and may also be promising for conventional breeding programs when only the additive portion of the total genetic variance can be used. The data support the general conclusion that the amount of heterosis is a function of genetic diversity between the two parents. Those breeders working on hybrid wheat may wish to look at winter x spring crosses as a means of maximizing heterosis. However, since a significant interaction between years x F1's was noted for the traits measured, more than one year of evaluation will be necessary if winter x spring crosses are employed. Title: Estimates of heterosis for five agronomic traits in selected winter x spring and winter x winter wheat crosses (Triticum aestivum L. em Thell) Author: Brajcich, P. Concern regarding the lack of genetic variability and the apparent yield plateau reached in wheat breeding have prompted this investigation. The systematic crossing of spring and winter wheat types which have evolved to form somewhat different gene pools, may provide a source of additional usable genetic variability for future yield increases. Five winter and five spring wheat cultivars with different degrees of genetic similarities in their pedigrees were crossed to obtain F1's and F2's. The parents plus winter x spring F1's were planted in two growing seasons at Hyslop Agronomy Farm near Corvallis, Oregon. During the second season the winter x spring F2 and winter x winter F1 crosses were also included. Agronomic traits were measured on an individual plant basis. These traits were plant height, number of tillers per plant, 100 kernel weight, number of kernels per spike and grain yield. Analyses of variance were conducted for each trait. Estimates of the amount of usable genetic variation were determined by heterosis values, inbreeding depression and parent-progeny standard regressions. Possible interactions between years and the above five characters were determined for the winter x spring F1's. Evidence of non-additive gene action was found in the expression of heterosis and subsequent inbreeding depression which depended on the specific trait measured and the parents involved in the cross. The greatest heterosis values were noted for grain yield per plant. Crosses with the winter parent, Weique Red Mace, resulted in the highest estimates for grain yield. This was due to the late maturity of these hybrids and to the diverse genetic background of this winter parent compared to the five spring parents. Parent-progeny regressions indicated that a large amount of additive genetic variance was present for plant height, 100 kernel weight and grain yield an intermediate amount for kernels per spike and tillers per plant. Winter x spring F1 crosses resulted in higher heterosis estimates and a wider range of values between crosses than winter x winter F1 crosses. Parent-progeny regression estimates were similar in value for the two types of F1 populations. Thus, these results indicate that the systematic crossing between winter and spring wheats will produce greater total genetic variability for further wheat improvement. This is true for the development of hybrid wheat (non-additive) and may also be promising for conventional breeding programs when only the additive portion of the total genetic variance can be used. The data support the general conclusion that the amount of heterosis is a function of genetic diversity between the two parents. Those breeders working on hybrid wheat may wish to look at winter x spring crosses as a means of maximizing heterosis. However, since a significant interaction between years x F1's was noted for the traits measured, more than one year of evaluation will be necessary if winter x spring crosses are employed. Close

• 18. [Article] The influence of various climate and edaphic factors on the toxicity of 2-tert. butylamino-4-ethylamino-6-methylthio-s-triazine (Igran) to winter wheat (Triticum aestivum Vill., Host)

  Several studies were conducted to determine the influence of various environmental factors on the toxicity of 2-tert.butylamino- 4-ethylamino-6-methylthio-s-triazirxe (Igran) to winter wheat. The effect ...

  Citation × Citation Citation Abstract Copy Title: The influence of various climate and edaphic factors on the toxicity of 2-tert. butylamino-4-ethylamino-6-methylthio-s-triazine (Igran) to winter wheat (Triticum aestivum Vill., Host) Author: Figuerola, Luis Fernan Several studies were conducted to determine the influence of various environmental factors on the toxicity of 2-tert.butylamino- 4-ethylamino-6-methylthio-s-triazirxe (Igran) to winter wheat. The effect of temperature on Igran toxicity was studied by growing wheat plants in pots submerged in water baths to control soil temperature and in controlled-environment chambers. Igran was more toxic to the test plants at 20-25 C than at 5-10 C. The lesser toxicity at low temperature appeared to be correlated in part with lower rates of absorption and translocation of the chemical. Light intensity was shown to influence the activity of Igran. High light intensity produced an effect similar to that of high temperature and it was difficult to separate the individual action for either climatic factor. The effect of Igran on photosynthesis of wheat plants was studied by measuring the CO₂ uptake with an infrared gas analyzer. The activity of Igran was more pronounced at high light intensity. Water availability in the soil influenced Igran action on winter wheat. The higher the water content in the soil, under high temperature and light intensity conditions, the higher the apparent absorption and translocation of Igran. This effect was related to the adsorptive capacity of soil particles. With increased water content in the soil, Igran apparently becomes more available to the roots than under low moisture conditions. High nitrogen content in the growth medium favored Igran toxic action on winter wheat. With lower nitrogen levels, although the growth rate was diminished, chlorosis and necrosis were not as noticeable as under high nitrogen content conditions. Igran was less toxic when applied directly to the soil surface than when incorporated into the soil. When the herbicide was placed close to the root system, the toxicity was greatly increased. Postemergence applications of Igran to the soil under high illumination (2500-3000 ft-c) and high temperature (20-30 C) produced severe injury to wheat even at low rates and at several stages of growth. At low light intensity (500-800 ft-c) and low temperature (5-10 C) few or no injury symptoms were observed. The determination of the factors affecting the toxicity of Igran on winter wheat will aid in making improved recommendations for its use to control a broad spectrum of undesired vegetation with a minimum chance for damage to wheat plants. Title: The influence of various climate and edaphic factors on the toxicity of 2-tert. butylamino-4-ethylamino-6-methylthio-s-triazine (Igran) to winter wheat (Triticum aestivum Vill., Host) Author: Figuerola, Luis Fernan Several studies were conducted to determine the influence of various environmental factors on the toxicity of 2-tert.butylamino- 4-ethylamino-6-methylthio-s-triazirxe (Igran) to winter wheat. The effect of temperature on Igran toxicity was studied by growing wheat plants in pots submerged in water baths to control soil temperature and in controlled-environment chambers. Igran was more toxic to the test plants at 20-25 C than at 5-10 C. The lesser toxicity at low temperature appeared to be correlated in part with lower rates of absorption and translocation of the chemical. Light intensity was shown to influence the activity of Igran. High light intensity produced an effect similar to that of high temperature and it was difficult to separate the individual action for either climatic factor. The effect of Igran on photosynthesis of wheat plants was studied by measuring the CO₂ uptake with an infrared gas analyzer. The activity of Igran was more pronounced at high light intensity. Water availability in the soil influenced Igran action on winter wheat. The higher the water content in the soil, under high temperature and light intensity conditions, the higher the apparent absorption and translocation of Igran. This effect was related to the adsorptive capacity of soil particles. With increased water content in the soil, Igran apparently becomes more available to the roots than under low moisture conditions. High nitrogen content in the growth medium favored Igran toxic action on winter wheat. With lower nitrogen levels, although the growth rate was diminished, chlorosis and necrosis were not as noticeable as under high nitrogen content conditions. Igran was less toxic when applied directly to the soil surface than when incorporated into the soil. When the herbicide was placed close to the root system, the toxicity was greatly increased. Postemergence applications of Igran to the soil under high illumination (2500-3000 ft-c) and high temperature (20-30 C) produced severe injury to wheat even at low rates and at several stages of growth. At low light intensity (500-800 ft-c) and low temperature (5-10 C) few or no injury symptoms were observed. The determination of the factors affecting the toxicity of Igran on winter wheat will aid in making improved recommendations for its use to control a broad spectrum of undesired vegetation with a minimum chance for damage to wheat plants. Close

• 19. [Article] The influence on winter wheat yields of competitive weedy species

  A study was conducted to compare the competitive ability with weeds of the short-strawed Gaines variety wheat and taller growing varieties under different fertility levels at three experimental locations. ...

  Citation × Citation Citation Abstract Copy Title: The influence on winter wheat yields of competitive weedy species Author: Albeke, William Edgar A study was conducted to compare the competitive ability with weeds of the short-strawed Gaines variety wheat and taller growing varieties under different fertility levels at three experimental locations. The experiments were designed so that the effects of variety, nitrogen fertilization, and weed competition could be evaluated. The interactions between these factors were also studied. Ryegrass (Loolium app.) and downy brome (Bromus tectorum) were the two weed species studied. Under high winter rainfall and ryegrass competition yields of wheat were seriously impaired in both the short and tall growing wheat varieties tested. As rates of nitrogen increased yields of wheat did not increase where a medium or heavy stand of ryegrass was present. Yield of wheat was reduced under high nitrogen and high ryegrass competition. A response to 60 pounds of nitrogen per acre was noted where no ryegrass competition was present. One hundred twenty pounds of nitrogen did not increase yields appreciably, especially in the Gaines variety. In the two remaining experiments, response to nitrogen fertilization was not as prominent due to lack of moisture throughout the growing season. However, downy brome competition decreased yields at one location under all three fertility levels. At the other location a poor stand of downy brome and arid conditions accounted for the lack of competitive effects. No differences were noted in competing abilities of the tall vs. the short growing varieties. In general it was concluded that in order to get maximum response from nitrogen fertilization in wheat, weeds would have to be controlled. Title: The influence on winter wheat yields of competitive weedy species Author: Albeke, William Edgar A study was conducted to compare the competitive ability with weeds of the short-strawed Gaines variety wheat and taller growing varieties under different fertility levels at three experimental locations. The experiments were designed so that the effects of variety, nitrogen fertilization, and weed competition could be evaluated. The interactions between these factors were also studied. Ryegrass (Loolium app.) and downy brome (Bromus tectorum) were the two weed species studied. Under high winter rainfall and ryegrass competition yields of wheat were seriously impaired in both the short and tall growing wheat varieties tested. As rates of nitrogen increased yields of wheat did not increase where a medium or heavy stand of ryegrass was present. Yield of wheat was reduced under high nitrogen and high ryegrass competition. A response to 60 pounds of nitrogen per acre was noted where no ryegrass competition was present. One hundred twenty pounds of nitrogen did not increase yields appreciably, especially in the Gaines variety. In the two remaining experiments, response to nitrogen fertilization was not as prominent due to lack of moisture throughout the growing season. However, downy brome competition decreased yields at one location under all three fertility levels. At the other location a poor stand of downy brome and arid conditions accounted for the lack of competitive effects. No differences were noted in competing abilities of the tall vs. the short growing varieties. In general it was concluded that in order to get maximum response from nitrogen fertilization in wheat, weeds would have to be controlled. Close

• 20. [Article] Association of selected traits with visual selection for yield in wheat (Triticum aestivum, L. em Thell.)

  Visual selection for grain yield may be a limiting factor in identifying superior yielding genotypes in a breeding program. This investigation was conducted (1) to compare the effectiveness of visual selection ...

  Citation × Citation Citation Abstract Copy Title: Association of selected traits with visual selection for yield in wheat (Triticum aestivum, L. em Thell.) Author: Marciniak, Michael E. Visual selection for grain yield may be a limiting factor in identifying superior yielding genotypes in a breeding program. This investigation was conducted (1) to compare the effectiveness of visual selection for grain yield by three selector groups representing different levels of plant breeding experience, and (2) to examine the association of selected traits with the process of evaluating plots visually for grain yield. The germplasm evaluated consisted of fifty non-segregating, diverse genotypes selected to include a wide range of expression for phenotypic characters. They were grown in solid-seeded, two-row plots with three replications in a randomized block design during 1981-1982. Data were collected on a plot basis for grain yield and twenty-two agronomic traits. Eighteen selectors were placed in three groups comprised of two plant breeders, eight graduate students, and eight summer student workers, respectively, from the Oregon State University cereal breeding program. Evaluations were made on two separate days by scoring each of the 150 plots on a scale of 1 to 5 for grain yield. The plant breeder selectors were the most successful of the three groups in discriminating both high and low yielding plots. The two best graduate student selectors were similar in ability to the plant breeders in scoring plots for high yield, although not in scoring for low yield. The remaining graduate student and summer worker selectors were generally not able to score more low and high yielding plots "correctly" than would be expected if selection were done at random. Considered individually, the most effective selectors failed to select several high yielding plots. However, when selections of the four most effective selectors were combined, only one of the twenty highest yielding plots was omitted. Results comparing trait association with actual plot grain yield and with selector scoring for plot grain yield suggested "biases" for or against certain traits. Biases for later heading and maturing plant types with wide flag leaves were common to all selector groups when visually selecting for high yield, as were earlier heading and maturing entries with narrower flag leaves when selecting for low yield. The plant breeder selectors were notable for lack of trait biases relative to other selector groups. In contrast, the summer worker selectors tended to overemphasize several spike characteristics whether selecting for high or low yield. Results suggested several other trait biases of individual selectors and selector groups. Title: Association of selected traits with visual selection for yield in wheat (Triticum aestivum, L. em Thell.) Author: Marciniak, Michael E. Visual selection for grain yield may be a limiting factor in identifying superior yielding genotypes in a breeding program. This investigation was conducted (1) to compare the effectiveness of visual selection for grain yield by three selector groups representing different levels of plant breeding experience, and (2) to examine the association of selected traits with the process of evaluating plots visually for grain yield. The germplasm evaluated consisted of fifty non-segregating, diverse genotypes selected to include a wide range of expression for phenotypic characters. They were grown in solid-seeded, two-row plots with three replications in a randomized block design during 1981-1982. Data were collected on a plot basis for grain yield and twenty-two agronomic traits. Eighteen selectors were placed in three groups comprised of two plant breeders, eight graduate students, and eight summer student workers, respectively, from the Oregon State University cereal breeding program. Evaluations were made on two separate days by scoring each of the 150 plots on a scale of 1 to 5 for grain yield. The plant breeder selectors were the most successful of the three groups in discriminating both high and low yielding plots. The two best graduate student selectors were similar in ability to the plant breeders in scoring plots for high yield, although not in scoring for low yield. The remaining graduate student and summer worker selectors were generally not able to score more low and high yielding plots "correctly" than would be expected if selection were done at random. Considered individually, the most effective selectors failed to select several high yielding plots. However, when selections of the four most effective selectors were combined, only one of the twenty highest yielding plots was omitted. Results comparing trait association with actual plot grain yield and with selector scoring for plot grain yield suggested "biases" for or against certain traits. Biases for later heading and maturing plant types with wide flag leaves were common to all selector groups when visually selecting for high yield, as were earlier heading and maturing entries with narrower flag leaves when selecting for low yield. The plant breeder selectors were notable for lack of trait biases relative to other selector groups. In contrast, the summer worker selectors tended to overemphasize several spike characteristics whether selecting for high or low yield. Results suggested several other trait biases of individual selectors and selector groups. Close