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• 141. [Article] Asulam for tansy ragwort control in alfalfa : field efficacy and selectivity factors

  Tansy ragwort (Senecio jacobaea L. ) is a poisonous weed which infests alfalfa fields in western Oregon. Studies were conducted to evaluate the effectiveness of asulam (methyl sulfanilylcarbamate)for control ...

  Citation × Citation Citation Abstract Copy Title: Asulam for tansy ragwort control in alfalfa : field efficacy and selectivity factors Author: Harper, Delbert Ray Tansy ragwort (Senecio jacobaea L. ) is a poisonous weed which infests alfalfa fields in western Oregon. Studies were conducted to evaluate the effectiveness of asulam (methyl sulfanilylcarbamate)for control of tansy ragwort in alfalfa and to elucidate factors responsible for its selectivity. In seven replicated field trials in 1973 and 1974, 2.2 kg/ha of asulam gave 70% to 90% control of tansy ragwort. No visible injury or yield reductions were recorded in alfalfa treated with rates of asulam up to 9. 0 kg/ha. Varying carrier volume from 38 to 151 L/ha or adding 0. 2% surfactant to the spray solution did not influence tansy ragwort control. In the greenhouse, rates of foliar applications of asulam sodium salt causing growth reductions of 50% (GR₅₀) were calculated by using the least-squares method. Estimated GR₅₀ values for alfalfa were 109 and 55 kg/ha, without and with surfactant, respectively. GR₅₀ values for tansy ragwort were 0.30 kg/ha without surfactant and 0.38 kg/ha with added surfactant. Spray retention by alfalfa and tansy ragwort was measured by using 2% acid red dye solutions and asulam sodium salt solutions. Increasing carrier volume increased spray retention in both species. Tansy ragwort retained an average of 2.5 times as much as alfalfa when no surfactant was added to the spray solution. When surfactant was added, the retention per unit leaf area was the same for each species. Retention by tansy ragwort was not influenced by surfactant but retention by alfalfa was 2.3 times as much with surfactant as without surfactant. The effects of surfactant and time of exposure on the uptake of ¹⁴C asulam solution into foliage of both species was measured. The treated portions were washed, activity in the wash water was measured, and uptake was calculated. Uptake of ¹⁴C asulam in both species was at a maximum 48 hr after treatment. Uptake by tansy ragwort was 1.9 times as high as in alfalfa when no surfactant was added to the spray solution. When surfactant was added, alfalfa absorbed 1.6 times as much asulam as tansy ragwort. The addition of surfactant increased uptake by alfalfa 2.7 times and did not significantly influence uptake by tansy ragwort. Tansy ragwort translocated 2.5 times as much ¹⁴C activity from the treated area as alfalfa when values were expressed as a percentage of the amount taken up. The amount translocated in alfalfa was independent of the amount of uptake; similar amounts of activity were found outside the treated area, even though 2.7 times as much was taken up when surfactant was added. Trans location by tansy ragwort was not affected by addition of surfactant. Metabolism of ¹⁴C asulam applied with surfactant was studied in both species. Plants were harvested 48, 96, and 144 hr after treatment and extracted with acetone. The aqueous residue of the acetone extract was partitioned with ethyl acetate and the ¹⁴C activity in the ethyl acetate phase, the aqueous phase, and the plant residue was determined. The total non-extracted activity was higher in alfalfa residues than tansy ragwort, but when the values were converted to a percentage of the amount of uptake, there were no significant differences between species. Alfalfa had significantly higher percentages of the ¹⁴C activity present in the aqueous phase than did tansy ragwort. There were significantly lower amounts of free ¹⁴C asulam in alfalfa than in tansy ragwort as determined by thin-layer chromatography. An unknown asulam metabolite was present in the ethyl acetate extracts of alfalfa while more than 75% of the ¹⁴C activity in ethyl acetate extracts of tansy ragwort was asulam. The aqueous extracts of both species apparently contained an acid-labile conjugate(s) of asulam. Results of the studies conducted do not completely account for differences in sensitivity found in the greenhouse. Other possible explanations for selectivity are discussed. Title: Asulam for tansy ragwort control in alfalfa : field efficacy and selectivity factors Author: Harper, Delbert Ray Tansy ragwort (Senecio jacobaea L. ) is a poisonous weed which infests alfalfa fields in western Oregon. Studies were conducted to evaluate the effectiveness of asulam (methyl sulfanilylcarbamate)for control of tansy ragwort in alfalfa and to elucidate factors responsible for its selectivity. In seven replicated field trials in 1973 and 1974, 2.2 kg/ha of asulam gave 70% to 90% control of tansy ragwort. No visible injury or yield reductions were recorded in alfalfa treated with rates of asulam up to 9. 0 kg/ha. Varying carrier volume from 38 to 151 L/ha or adding 0. 2% surfactant to the spray solution did not influence tansy ragwort control. In the greenhouse, rates of foliar applications of asulam sodium salt causing growth reductions of 50% (GR₅₀) were calculated by using the least-squares method. Estimated GR₅₀ values for alfalfa were 109 and 55 kg/ha, without and with surfactant, respectively. GR₅₀ values for tansy ragwort were 0.30 kg/ha without surfactant and 0.38 kg/ha with added surfactant. Spray retention by alfalfa and tansy ragwort was measured by using 2% acid red dye solutions and asulam sodium salt solutions. Increasing carrier volume increased spray retention in both species. Tansy ragwort retained an average of 2.5 times as much as alfalfa when no surfactant was added to the spray solution. When surfactant was added, the retention per unit leaf area was the same for each species. Retention by tansy ragwort was not influenced by surfactant but retention by alfalfa was 2.3 times as much with surfactant as without surfactant. The effects of surfactant and time of exposure on the uptake of ¹⁴C asulam solution into foliage of both species was measured. The treated portions were washed, activity in the wash water was measured, and uptake was calculated. Uptake of ¹⁴C asulam in both species was at a maximum 48 hr after treatment. Uptake by tansy ragwort was 1.9 times as high as in alfalfa when no surfactant was added to the spray solution. When surfactant was added, alfalfa absorbed 1.6 times as much asulam as tansy ragwort. The addition of surfactant increased uptake by alfalfa 2.7 times and did not significantly influence uptake by tansy ragwort. Tansy ragwort translocated 2.5 times as much ¹⁴C activity from the treated area as alfalfa when values were expressed as a percentage of the amount taken up. The amount translocated in alfalfa was independent of the amount of uptake; similar amounts of activity were found outside the treated area, even though 2.7 times as much was taken up when surfactant was added. Trans location by tansy ragwort was not affected by addition of surfactant. Metabolism of ¹⁴C asulam applied with surfactant was studied in both species. Plants were harvested 48, 96, and 144 hr after treatment and extracted with acetone. The aqueous residue of the acetone extract was partitioned with ethyl acetate and the ¹⁴C activity in the ethyl acetate phase, the aqueous phase, and the plant residue was determined. The total non-extracted activity was higher in alfalfa residues than tansy ragwort, but when the values were converted to a percentage of the amount of uptake, there were no significant differences between species. Alfalfa had significantly higher percentages of the ¹⁴C activity present in the aqueous phase than did tansy ragwort. There were significantly lower amounts of free ¹⁴C asulam in alfalfa than in tansy ragwort as determined by thin-layer chromatography. An unknown asulam metabolite was present in the ethyl acetate extracts of alfalfa while more than 75% of the ¹⁴C activity in ethyl acetate extracts of tansy ragwort was asulam. The aqueous extracts of both species apparently contained an acid-labile conjugate(s) of asulam. Results of the studies conducted do not completely account for differences in sensitivity found in the greenhouse. Other possible explanations for selectivity are discussed. Close

• 142. [Article] The Biogeochemistry of nitrogen and phosphorus cycling in native shrub ecosystems in Senegal

  Two native shrub species (Piliostigma reticulatum and Guiera senegalensis) are prominent vegetation components in farmers’ fields in Senegal. However, their role in nutrient cycling and ecosystem function ...

  Citation × Citation Citation Abstract Copy Title: The Biogeochemistry of nitrogen and phosphorus cycling in native shrub ecosystems in Senegal Author: Dossa, Ekw'e Lokossou, 1960- Two native shrub species (Piliostigma reticulatum and Guiera senegalensis) are prominent vegetation components in farmers’ fields in Senegal. However, their role in nutrient cycling and ecosystem function has largely been overlooked. A study including both laboratory and field experiments was conducted to evaluate potential biophysical interactions of the two shrub species with soils and crops in Senegal. Carbon (C), nitrogen (N) and phosphorus (P) mineralization potential of soils incubated with residues of the two shrubs species was studied in laboratory conditions. Additionally, the effect of shrub-residue amendment on P sorption by soils was examined. Under field conditions, the effect of presence or absence of shrubs on crop productivity and nutrient recycling in soil was investigated. Another study examined shrub species effect on spatial distribution of nutrients and P fractions. Results showed shrub residues used as amendments immobilized N and P, which suggested these residues have limited value as immediate nutrient sources for crops. However, soils amended with shrub residues sorbed less P than unamended soils, indicating that when added to P-fixing soils, shrub residues could improve P availability to crops. In the absence of fertilization or when water was limiting, shrubs increased crop yield, likely through a combination of improved soil quality and water conditions associated with the shrub canopy and rhizosphere. The presence of shrubs increased nutrient-use efficiency over sole crop systems. Shrubs were shown to create “islands of fertility” that had greater C, N and P concentrations under their canopies than in open areas. Shrubs differed in their ability to modify soil properties. G. senegalensis had higher soil C and N under its canopy and lower pH than P. reticulatum. Sequential extraction of P fractions showed that NaOH-P, most of which is organic P, was the dominant P fraction in the soils. These results showed that, in the Sahel, shrubs are important components of cropping systems that should be conserved and actively managed. Title: The Biogeochemistry of nitrogen and phosphorus cycling in native shrub ecosystems in Senegal Author: Dossa, Ekw'e Lokossou, 1960- Two native shrub species (Piliostigma reticulatum and Guiera senegalensis) are prominent vegetation components in farmers’ fields in Senegal. However, their role in nutrient cycling and ecosystem function has largely been overlooked. A study including both laboratory and field experiments was conducted to evaluate potential biophysical interactions of the two shrub species with soils and crops in Senegal. Carbon (C), nitrogen (N) and phosphorus (P) mineralization potential of soils incubated with residues of the two shrubs species was studied in laboratory conditions. Additionally, the effect of shrub-residue amendment on P sorption by soils was examined. Under field conditions, the effect of presence or absence of shrubs on crop productivity and nutrient recycling in soil was investigated. Another study examined shrub species effect on spatial distribution of nutrients and P fractions. Results showed shrub residues used as amendments immobilized N and P, which suggested these residues have limited value as immediate nutrient sources for crops. However, soils amended with shrub residues sorbed less P than unamended soils, indicating that when added to P-fixing soils, shrub residues could improve P availability to crops. In the absence of fertilization or when water was limiting, shrubs increased crop yield, likely through a combination of improved soil quality and water conditions associated with the shrub canopy and rhizosphere. The presence of shrubs increased nutrient-use efficiency over sole crop systems. Shrubs were shown to create “islands of fertility” that had greater C, N and P concentrations under their canopies than in open areas. Shrubs differed in their ability to modify soil properties. G. senegalensis had higher soil C and N under its canopy and lower pH than P. reticulatum. Sequential extraction of P fractions showed that NaOH-P, most of which is organic P, was the dominant P fraction in the soils. These results showed that, in the Sahel, shrubs are important components of cropping systems that should be conserved and actively managed. Close

• 143. [Article] Welfare Effects of the Federal Crop Insurance Program : The Sufficient Statistics Approach

  The publicly subsidized Federal Crop Insurance Program has expanded rapidly in recent decades in the United States. With the reform in the 2014 Farm Bill, the Federal Crop Insurance Program has become ...

  Citation × Citation Citation Abstract Copy Title: Welfare Effects of the Federal Crop Insurance Program : The Sufficient Statistics Approach Author: Yu, Jialing The publicly subsidized Federal Crop Insurance Program has expanded rapidly in recent decades in the United States. With the reform in the 2014 Farm Bill, the Federal Crop Insurance Program has become the most important component of U.S. farm policies. The primary goal of the program is to provide risk protections for farmers. However, there is sporadic evidence of welfare costs associated with the program due to moral hazard, adverse selection, deadweight loss from the subsidy transfer and transaction costs. To provide a complete and systematic assessment, it requires a thorough theoretical understandings and credible empirical measurement of the welfare effect of the Federal Crop Insurance Program. We apply the sufficient statistics approach to consolidate various welfare effects of crop insurance and to provide quantitative evidence for the welfare analysis. We analyze a model in a setting where information asymmetry and systemic risk form an adverse environment for private sectors to provide insurance and therefore create a need for government intervention. From the model, we derive the condition for optimal contract and identify key parameters that affect the welfare effects of risk protection, information asymmetry, and premium subsidy. The results not only provide policy implications and but also suggest the key parameters needed for measuring the welfare effect of publically provided crop insurance programs empirically. To measure the welfare effect of the Federal Crop Insurance Program, we need to understand how the program affects the distribution of revenue. To this end, a moment-based approach is used to estimate the reduced-form equations of the first two moments of revenue distributions using farm-level Agricultural Census data from the U.S. Heartland region for 2002, 2007 and 2012. The control function approach is applied to control for the endogeneity problem caused by the self-selection of insurance coverage, under the assumption that selection into different coverage level is based on a set of observed covariates and time-invariant factors. Our results show that increase in coverage level is associated with a lower mean and higher variability of farm revenue per acre. The impacts of insurance coverage on the revenue distribution, as a reduced-form representation of the moral hazard, suggest a welfare loss. Other key parameters affecting marginal welfare effects of the Federal Crop Insurance Program include risk attitude parameters, insurance demand elasticity with respect to price, the impacts of insurance coverage on the production outcomes, marginal welfare cost of deadweight loss, and loading factors. We collect the information on the range of the values of these parameters from existing literatures. The Bootstrap method is applied to estimate marginal welfare effects discussed in the conceptual model. The results suggest that under the current policy setting, the net marginal welfare effects of coverage level and subsidy rate are both negative, suggesting that both the coverage level and the subsidy rate are greater than their optimal level. However, from farmers’ perspectives, the current risk protection level is appropriate. Title: Welfare Effects of the Federal Crop Insurance Program : The Sufficient Statistics Approach Author: Yu, Jialing The publicly subsidized Federal Crop Insurance Program has expanded rapidly in recent decades in the United States. With the reform in the 2014 Farm Bill, the Federal Crop Insurance Program has become the most important component of U.S. farm policies. The primary goal of the program is to provide risk protections for farmers. However, there is sporadic evidence of welfare costs associated with the program due to moral hazard, adverse selection, deadweight loss from the subsidy transfer and transaction costs. To provide a complete and systematic assessment, it requires a thorough theoretical understandings and credible empirical measurement of the welfare effect of the Federal Crop Insurance Program. We apply the sufficient statistics approach to consolidate various welfare effects of crop insurance and to provide quantitative evidence for the welfare analysis. We analyze a model in a setting where information asymmetry and systemic risk form an adverse environment for private sectors to provide insurance and therefore create a need for government intervention. From the model, we derive the condition for optimal contract and identify key parameters that affect the welfare effects of risk protection, information asymmetry, and premium subsidy. The results not only provide policy implications and but also suggest the key parameters needed for measuring the welfare effect of publically provided crop insurance programs empirically. To measure the welfare effect of the Federal Crop Insurance Program, we need to understand how the program affects the distribution of revenue. To this end, a moment-based approach is used to estimate the reduced-form equations of the first two moments of revenue distributions using farm-level Agricultural Census data from the U.S. Heartland region for 2002, 2007 and 2012. The control function approach is applied to control for the endogeneity problem caused by the self-selection of insurance coverage, under the assumption that selection into different coverage level is based on a set of observed covariates and time-invariant factors. Our results show that increase in coverage level is associated with a lower mean and higher variability of farm revenue per acre. The impacts of insurance coverage on the revenue distribution, as a reduced-form representation of the moral hazard, suggest a welfare loss. Other key parameters affecting marginal welfare effects of the Federal Crop Insurance Program include risk attitude parameters, insurance demand elasticity with respect to price, the impacts of insurance coverage on the production outcomes, marginal welfare cost of deadweight loss, and loading factors. We collect the information on the range of the values of these parameters from existing literatures. The Bootstrap method is applied to estimate marginal welfare effects discussed in the conceptual model. The results suggest that under the current policy setting, the net marginal welfare effects of coverage level and subsidy rate are both negative, suggesting that both the coverage level and the subsidy rate are greater than their optimal level. However, from farmers’ perspectives, the current risk protection level is appropriate. Close

• 144. [Article] Varietal differences in response of winter wheat varieties to nitrogen fertilizer and environment

  The purpose of this study was to evaluate differences between winter wheat varieties in response to nitrogen fertilizer. Seven nitrogen fertilizer rate x variety factorial experiments were conducted in ...

  Citation × Citation Citation Abstract Copy Title: Varietal differences in response of winter wheat varieties to nitrogen fertilizer and environment Author: Ambler, John Richard The purpose of this study was to evaluate differences between winter wheat varieties in response to nitrogen fertilizer. Seven nitrogen fertilizer rate x variety factorial experiments were conducted in several environments. Dry matter and nitrogen yields at boot, soft dough, and harvest and grain yield components were measured. The yield component data were evaluated in terms of storage capacity which is assumed to be proportional to kernels /rn² for a given variety. The kernels /m² was divided into two components, spikes /rn² and kernels/spike. The spikes /m² of each variety were closely related to the boot nitrogen yield, but not to boot dry matter yield or plant nitrogen content. Since the kernels/spike generally remained constant or increased as the boot nitrogen yield increased, the kernels/m² appeared to depend on the boot nitrogen yield. The variety Hyslop had high dry matter and nitrogen yields at boot stage of growth. This appears to allow it to have excellent storage capacity as measured by kernels /m² . Good growth by boot stage appears to lower the nitrogen fertilizer rate needed for maximum grain yields. The variety Nugaines had relatively low growth and nitrogen uptake by boot. This may be the reason why it needs a higher fertilizer rate than Hyslop to obtain adequate storage capacity (kernels/m² ). However; Nugaines had better growth after soft dough stage. At the dryland locations this may be due to slower depletion of the soil water. At the irrigated locations it may be due to greater late tillering. Hyslop and Nugaines differed in the pattern of yield component adjustment to improving environment. Hyslop mainly increased its average kernels/spike rather than spikes/m² . Nugaines had greater increases in spikes/m² but smaller increases in kernels/spike. This may be related to their different cuim sizes and tillering. Hyslop forms a few large culms early in the season, but Nugaines continues to tiller during stem elongation. Coulee was intermediate between Hyslop and Nugaines in patterns of growth over time and pattern of yield component adjustment to improving environment. It had good yields at moderate nitrogen rates, and high nitrogen rates did not appear to be needed for adequate storage capacity. Wanser consistently had low grain yields, which was due to low kernels/m² . Nitrogen fertilizer increased its height more than the shorter varieties and this was associated with reductions in kernels/spike: Thus the height growth of Wanser may compete with its ear development and cause poor storage capacity. Wanser had slightly greater grain nitrogen percentage than other varieties, but this was simply associated with its low grain yield. There were only small varietal differences in the percentage of plant nitrogen translocated to grain. However, environment and nitrogen fertilizer rate greatly affected this. The club wheat Paha yielded well but usually less than some other varieties. It had high dry matter and nitrogen yields, but after soft dough its dry matter yields decreased more than for other varieties. This indicated that it depleted soil moisture earlier than other varieties did. Tx65A1268, a short hard red winter wheat with prolific tillering and small culms, was included in. two experiments. It had the highest grain yield at the low rainfall site. This may be related to its early maturity. However, with irrigation it yielded poorly. This appeared to be due to poor storage capacity since there was no increase in kernels/spike with improving environment. Yamhill, an awnletted wheat, yielded well in the Willamette Valley, but not in eastern Oregon. Estimates of the recovery of fertilizer nitrogen were calculated from the increases in soft dough nitrogen yield caused by each increment of nitrogen fertilizer. At sites with excellent moisture supply the first fertilizer increment was incompletely recovered (44-66%), apparently due to immobilization associated with plant residue decay. With higher fertilizer increments which increased yields, fertilizer recovery values were near 100%. At low rainfall sites under fallow cropping recovery values were 38-56% and decreased with above optimum fertilizer rates. At eastern Oregon sites losses of nitrogen from the plant tops after soft dough ranged from 7-33% depending on variety, location, and fertilizer rate. At maturity the percentage of the total plant top nitrogen in the grain ranged from 60-81%. This percentage decreased with nitrogen fertilization, but was little affected by variety. Title: Varietal differences in response of winter wheat varieties to nitrogen fertilizer and environment Author: Ambler, John Richard The purpose of this study was to evaluate differences between winter wheat varieties in response to nitrogen fertilizer. Seven nitrogen fertilizer rate x variety factorial experiments were conducted in several environments. Dry matter and nitrogen yields at boot, soft dough, and harvest and grain yield components were measured. The yield component data were evaluated in terms of storage capacity which is assumed to be proportional to kernels /rn² for a given variety. The kernels /m² was divided into two components, spikes /rn² and kernels/spike. The spikes /m² of each variety were closely related to the boot nitrogen yield, but not to boot dry matter yield or plant nitrogen content. Since the kernels/spike generally remained constant or increased as the boot nitrogen yield increased, the kernels/m² appeared to depend on the boot nitrogen yield. The variety Hyslop had high dry matter and nitrogen yields at boot stage of growth. This appears to allow it to have excellent storage capacity as measured by kernels /m² . Good growth by boot stage appears to lower the nitrogen fertilizer rate needed for maximum grain yields. The variety Nugaines had relatively low growth and nitrogen uptake by boot. This may be the reason why it needs a higher fertilizer rate than Hyslop to obtain adequate storage capacity (kernels/m² ). However; Nugaines had better growth after soft dough stage. At the dryland locations this may be due to slower depletion of the soil water. At the irrigated locations it may be due to greater late tillering. Hyslop and Nugaines differed in the pattern of yield component adjustment to improving environment. Hyslop mainly increased its average kernels/spike rather than spikes/m² . Nugaines had greater increases in spikes/m² but smaller increases in kernels/spike. This may be related to their different cuim sizes and tillering. Hyslop forms a few large culms early in the season, but Nugaines continues to tiller during stem elongation. Coulee was intermediate between Hyslop and Nugaines in patterns of growth over time and pattern of yield component adjustment to improving environment. It had good yields at moderate nitrogen rates, and high nitrogen rates did not appear to be needed for adequate storage capacity. Wanser consistently had low grain yields, which was due to low kernels/m² . Nitrogen fertilizer increased its height more than the shorter varieties and this was associated with reductions in kernels/spike: Thus the height growth of Wanser may compete with its ear development and cause poor storage capacity. Wanser had slightly greater grain nitrogen percentage than other varieties, but this was simply associated with its low grain yield. There were only small varietal differences in the percentage of plant nitrogen translocated to grain. However, environment and nitrogen fertilizer rate greatly affected this. The club wheat Paha yielded well but usually less than some other varieties. It had high dry matter and nitrogen yields, but after soft dough its dry matter yields decreased more than for other varieties. This indicated that it depleted soil moisture earlier than other varieties did. Tx65A1268, a short hard red winter wheat with prolific tillering and small culms, was included in. two experiments. It had the highest grain yield at the low rainfall site. This may be related to its early maturity. However, with irrigation it yielded poorly. This appeared to be due to poor storage capacity since there was no increase in kernels/spike with improving environment. Yamhill, an awnletted wheat, yielded well in the Willamette Valley, but not in eastern Oregon. Estimates of the recovery of fertilizer nitrogen were calculated from the increases in soft dough nitrogen yield caused by each increment of nitrogen fertilizer. At sites with excellent moisture supply the first fertilizer increment was incompletely recovered (44-66%), apparently due to immobilization associated with plant residue decay. With higher fertilizer increments which increased yields, fertilizer recovery values were near 100%. At low rainfall sites under fallow cropping recovery values were 38-56% and decreased with above optimum fertilizer rates. At eastern Oregon sites losses of nitrogen from the plant tops after soft dough ranged from 7-33% depending on variety, location, and fertilizer rate. At maturity the percentage of the total plant top nitrogen in the grain ranged from 60-81%. This percentage decreased with nitrogen fertilization, but was little affected by variety. Close

• 145. [Article] Factors affecting the action of 1,8 naphthalic anhydride in corn treated with s-ethyl dipropylthiocarbamate (EPTC)

  The antidote (1, 8 naphthalic anhydride) is recommended for corn protection against EPTC injury where the antidote is applied at a half percent by weight of corn seeds before planting. Studies were conducted ...

  Citation × Citation Citation Abstract Copy Title: Factors affecting the action of 1,8 naphthalic anhydride in corn treated with s-ethyl dipropylthiocarbamate (EPTC) Author: Guneyli, Ercan The antidote (1, 8 naphthalic anhydride) is recommended for corn protection against EPTC injury where the antidote is applied at a half percent by weight of corn seeds before planting. Studies were conducted to determine the factors affecting the action of antidote in corn (Zea mays L. var. NB 501D) treated with s-ethyl dipropylthio- carbamate (EPTC). The antidote did not affect germination percentage and germination rate index of corn treated with 0, 2, 4, 6 and 8 ppm of EPTC. There was slight stimulation of corn germination by EPTC. Emergence of antidote-treated corn was slow from Bashaw clay loam, Chehalis sandy loam and Woodburn silty loam soils that were treated with 0, 3, 6, 9 and 12 lb/A of EPTC. Slight stimulation of corn emergence percentage and rate index values were caused by EPTC at 3, 6 and 9 lb/A rates. Emergence percentage of corn was 88, 91 and 92 percent for clay loam, silty loam, and sandy loam soils, respectively. When the corn root and shoot length was measured six days after corn germination at 0, 4 and 8 ppm of EPTC it was found that EPTC increased shoot length whereas antidote reduced it. There was slight reduction in the root length of antidote treated and non- treated corn seedlings at 8 ppm of EPTC. When the shoot development of corn was used as a criterion for antidote action at the 12 lb/A rate of EPTC it was found that antidote was the most effective during the first 48 hours of seedling development. Uptake studies with antidote suggested that it is absorbed by corn seed, shoot and roots. However, the root application of antidote was inhibitory to the first primary root of corn. When antidote was applied at 40 lb/A rate to the root zone and soil surface, there was 5 and 12 percent protection, respectively. The seed application of antidote completely protected corn from the herbicidal injury of EPTC applied at 12 lb/A rate. Studies with clay loam, silty loam and sandy loam soils showed that clay loam retained most of the EPTC applied at 3, 6, 9 and 12 lb/A rate without subsequently injuring corn. Antidote-treated plants seemed to be more injured by EPTC than the non-treated ones. However, antidote protected corn in sandy loam and silty loam soils at every level of EPTC. Low and high light intensities did not affect the action of antidote in corn treated with 0, 3, 6, 9 and 12 lb/A of EPTC. Antidote did not protect corn from EPTC injury at low temperature (20 C) at both low and high light intensity (1800 vs. 800 ft-c). On the contrary antidote-treated plants were injured more than the non-treated ones at 20 C. Antidote successfully protected corn from EPTC injury at high temperature (30 C). The light intensity was not a factor affecting the action of antidote in corn. Applications of antidote at 0, 1, 2, and 4 days indicated that protection by antidote was not complete after the 2nd day of applica- tion. Antidote was most protective when applied at 0 and 1 day after subjecting corn to 12 lb/A rate of EPTC. When 12 lb/A rate of EPTC was applied to antidote-treated and non-treated corn at 0, 1, 2, 4 and 8 day intervals it was found that antidote would protect corn at every application period. Antidote-treated corn seedlings absorbed more ¹⁴C-EPTC than non-treated ones. However, antidote-treated corn plants were also stimulated in metabolizing EPTC. When ¹⁴C-EPTC-treated corn seedlings were harvested and separated into root, shoot and seed sections at 1, 3, 6 and 9 day intervals it was found that antidote-treated plants metabolized 12 lb/A rate of EPTC more than the non-treated ones. It could be assumed that antidote activated the enzyme system(s) responsible for EPTC breakdown in corn seedlings. Thin layer chromatography studies showed five to six major metabolite peaks for 1 and 3-day old corn seedlings treated with ¹⁴C-EPTC. The peaks had the same R[subscript f] values both for antidote- treated and non-treated plants. Scanning of the radioactive peaks also indicated a higher rate of EPTC metabolism in corn seedlings that were treated with antidote than the non-treated ones. Studies were also conducted to check the possibility of gibber- ellic acid involvement as a regulator of the EPTC-metabolizing enzyme system. Findings indicated that GA₃ alone partially protected corn from EPTC injury whereas GA₃ along with antidote treatment significantly increased the corn dry matter production. However, CCC (cycocel) treatments of corn seeds significantly induced EPTC injury to corn. Title: Factors affecting the action of 1,8 naphthalic anhydride in corn treated with s-ethyl dipropylthiocarbamate (EPTC) Author: Guneyli, Ercan The antidote (1, 8 naphthalic anhydride) is recommended for corn protection against EPTC injury where the antidote is applied at a half percent by weight of corn seeds before planting. Studies were conducted to determine the factors affecting the action of antidote in corn (Zea mays L. var. NB 501D) treated with s-ethyl dipropylthio- carbamate (EPTC). The antidote did not affect germination percentage and germination rate index of corn treated with 0, 2, 4, 6 and 8 ppm of EPTC. There was slight stimulation of corn germination by EPTC. Emergence of antidote-treated corn was slow from Bashaw clay loam, Chehalis sandy loam and Woodburn silty loam soils that were treated with 0, 3, 6, 9 and 12 lb/A of EPTC. Slight stimulation of corn emergence percentage and rate index values were caused by EPTC at 3, 6 and 9 lb/A rates. Emergence percentage of corn was 88, 91 and 92 percent for clay loam, silty loam, and sandy loam soils, respectively. When the corn root and shoot length was measured six days after corn germination at 0, 4 and 8 ppm of EPTC it was found that EPTC increased shoot length whereas antidote reduced it. There was slight reduction in the root length of antidote treated and non- treated corn seedlings at 8 ppm of EPTC. When the shoot development of corn was used as a criterion for antidote action at the 12 lb/A rate of EPTC it was found that antidote was the most effective during the first 48 hours of seedling development. Uptake studies with antidote suggested that it is absorbed by corn seed, shoot and roots. However, the root application of antidote was inhibitory to the first primary root of corn. When antidote was applied at 40 lb/A rate to the root zone and soil surface, there was 5 and 12 percent protection, respectively. The seed application of antidote completely protected corn from the herbicidal injury of EPTC applied at 12 lb/A rate. Studies with clay loam, silty loam and sandy loam soils showed that clay loam retained most of the EPTC applied at 3, 6, 9 and 12 lb/A rate without subsequently injuring corn. Antidote-treated plants seemed to be more injured by EPTC than the non-treated ones. However, antidote protected corn in sandy loam and silty loam soils at every level of EPTC. Low and high light intensities did not affect the action of antidote in corn treated with 0, 3, 6, 9 and 12 lb/A of EPTC. Antidote did not protect corn from EPTC injury at low temperature (20 C) at both low and high light intensity (1800 vs. 800 ft-c). On the contrary antidote-treated plants were injured more than the non-treated ones at 20 C. Antidote successfully protected corn from EPTC injury at high temperature (30 C). The light intensity was not a factor affecting the action of antidote in corn. Applications of antidote at 0, 1, 2, and 4 days indicated that protection by antidote was not complete after the 2nd day of applica- tion. Antidote was most protective when applied at 0 and 1 day after subjecting corn to 12 lb/A rate of EPTC. When 12 lb/A rate of EPTC was applied to antidote-treated and non-treated corn at 0, 1, 2, 4 and 8 day intervals it was found that antidote would protect corn at every application period. Antidote-treated corn seedlings absorbed more ¹⁴C-EPTC than non-treated ones. However, antidote-treated corn plants were also stimulated in metabolizing EPTC. When ¹⁴C-EPTC-treated corn seedlings were harvested and separated into root, shoot and seed sections at 1, 3, 6 and 9 day intervals it was found that antidote-treated plants metabolized 12 lb/A rate of EPTC more than the non-treated ones. It could be assumed that antidote activated the enzyme system(s) responsible for EPTC breakdown in corn seedlings. Thin layer chromatography studies showed five to six major metabolite peaks for 1 and 3-day old corn seedlings treated with ¹⁴C-EPTC. The peaks had the same R[subscript f] values both for antidote- treated and non-treated plants. Scanning of the radioactive peaks also indicated a higher rate of EPTC metabolism in corn seedlings that were treated with antidote than the non-treated ones. Studies were also conducted to check the possibility of gibber- ellic acid involvement as a regulator of the EPTC-metabolizing enzyme system. Findings indicated that GA₃ alone partially protected corn from EPTC injury whereas GA₃ along with antidote treatment significantly increased the corn dry matter production. However, CCC (cycocel) treatments of corn seeds significantly induced EPTC injury to corn. Close

• 146. [Article] Inheritance of plant height in barley (Hordeum vulgare L. Emed. LAM.)

  Four, six-rowed, spring barley cultivars were used as parental material in this study. The parents were distinctly different in plant height. Washington-6124-62 is a standard height selection while Short ...

  Citation × Citation Citation Abstract Copy Title: Inheritance of plant height in barley (Hordeum vulgare L. Emed. LAM.) Author: Bayraktar, Ali Four, six-rowed, spring barley cultivars were used as parental material in this study. The parents were distinctly different in plant height. Washington-6124-62 is a standard height selection while Short Wocus and Minn. 66-102 are intermediate. The fourth parent was a dwarf selection obtained from India. The two intermediate cultivars and the dwarf cultivar were crossed to the tall parent, Wa-6124-62, with a portion of the F₁ progeny backcrossed to the shorter parent. In addition, the intermediate parent, Short Wocus, was crossed to Indian Dwarf. The following generations were available for study: parents, BC₁F₁, F₁, and F₂. The purpose of this study was to obtain information concerning the inheritance of plant height and to determine when selection for this trait could be made in the breeding program most effectively. To achieve this objective heritability and the mode of gene action were studied as well as number of genes segregating for plant height. The effect of temperature on plant height was also investigated in a growth chamber utilizing two temperature levels, 19° C and 30° C. Plant height was recorded on an individual plant basis at two sites that were distinctly different environmentally and in the growth chamber. The number of nodes were counted, and the length of internodes measured for genetic interpretation of culm length. Broad sense heritability values for plant height of each cross were estimated by using the variance of parents, F₁'s and F₂' s. Heritability values were quite high in the F₂ generation ranging from 50 to 90 percent, and suggest that plant phenotype gave a relatively good indication of the genotype for plant height. Height of the F₁ plants was between the mid-parent and tall parent indicating partial dominance for tall culm length. In earlier studies, many investigators found that additive gene action was the major component of genetic variability for plant height. Results obtained from this study suggest that the nature of gene action is a function of the parents used. Where large differences exist between parents, plant height appeared to be largely influenced by non-additive gene action. When the parents were similar in height the trait was controlled mainly by additive gene action. Fairly discrete height classes in the segregating populations indicated that plant height was controlled by only a few genetic factors in these populations. Ratios obtained from segregating populations suggested the presence of three recessive genetic factors for short height in the dwarf parent (Indian Dwarf). The tall parent, Wa-6124-62, and intermediate parent, Minn. 66-102, appeared to differ for plant height by one major genetic factor. Difference in height among the cultivars was mostly due to difference in internode length rather than the number of nodes. It was concluded that the rather simple inheritance of plant height in barley will allow effective selection in the F₂ generation for short stature, and progress to develop semi-dwarf barley cultivars should be possible if stiffness of straw can also be obtained along with short stature. In the cross between the tall and dwarf parent, selection for intermediate plant height would be more effective if delayed for several generations of selfing due to the relatively large dominance component of genetic variance. Title: Inheritance of plant height in barley (Hordeum vulgare L. Emed. LAM.) Author: Bayraktar, Ali Four, six-rowed, spring barley cultivars were used as parental material in this study. The parents were distinctly different in plant height. Washington-6124-62 is a standard height selection while Short Wocus and Minn. 66-102 are intermediate. The fourth parent was a dwarf selection obtained from India. The two intermediate cultivars and the dwarf cultivar were crossed to the tall parent, Wa-6124-62, with a portion of the F₁ progeny backcrossed to the shorter parent. In addition, the intermediate parent, Short Wocus, was crossed to Indian Dwarf. The following generations were available for study: parents, BC₁F₁, F₁, and F₂. The purpose of this study was to obtain information concerning the inheritance of plant height and to determine when selection for this trait could be made in the breeding program most effectively. To achieve this objective heritability and the mode of gene action were studied as well as number of genes segregating for plant height. The effect of temperature on plant height was also investigated in a growth chamber utilizing two temperature levels, 19° C and 30° C. Plant height was recorded on an individual plant basis at two sites that were distinctly different environmentally and in the growth chamber. The number of nodes were counted, and the length of internodes measured for genetic interpretation of culm length. Broad sense heritability values for plant height of each cross were estimated by using the variance of parents, F₁'s and F₂' s. Heritability values were quite high in the F₂ generation ranging from 50 to 90 percent, and suggest that plant phenotype gave a relatively good indication of the genotype for plant height. Height of the F₁ plants was between the mid-parent and tall parent indicating partial dominance for tall culm length. In earlier studies, many investigators found that additive gene action was the major component of genetic variability for plant height. Results obtained from this study suggest that the nature of gene action is a function of the parents used. Where large differences exist between parents, plant height appeared to be largely influenced by non-additive gene action. When the parents were similar in height the trait was controlled mainly by additive gene action. Fairly discrete height classes in the segregating populations indicated that plant height was controlled by only a few genetic factors in these populations. Ratios obtained from segregating populations suggested the presence of three recessive genetic factors for short height in the dwarf parent (Indian Dwarf). The tall parent, Wa-6124-62, and intermediate parent, Minn. 66-102, appeared to differ for plant height by one major genetic factor. Difference in height among the cultivars was mostly due to difference in internode length rather than the number of nodes. It was concluded that the rather simple inheritance of plant height in barley will allow effective selection in the F₂ generation for short stature, and progress to develop semi-dwarf barley cultivars should be possible if stiffness of straw can also be obtained along with short stature. In the cross between the tall and dwarf parent, selection for intermediate plant height would be more effective if delayed for several generations of selfing due to the relatively large dominance component of genetic variance. Close

• 147. [Article] Linking soluble C to microbial community composition and dynamics during decomposition of ¹³C-labeled ryegrass

  Ryegrass residue consists of three main C fractions: readily available soluble C, intermediately available cellulose and hemicellulose, and slowly available lignin. Changes in chemical composition during ...

  Citation × Citation Citation Abstract Copy Title: Linking soluble C to microbial community composition and dynamics during decomposition of ¹³C-labeled ryegrass Author: McMahon, Shawna K. Ryegrass residue consists of three main C fractions: readily available soluble C, intermediately available cellulose and hemicellulose, and slowly available lignin. Changes in chemical composition during decomposition influence rate of degradation as well as composition of the microbial community involved. Use of ¹³C-labeled plant material coupled with analysis of phospholipid fatty acids (PLEA) by isotope ratio mass spectrometry results in a powerful tool for linking microbial community structure and C cycling processes during decomposition. The objective was to investigate the role of soluble C in the decomposition of ryegrass straw. We wanted to determine (i) if the presence or absence of labile C in straw affects C mineralization by the microbial community, (ii) if community structure would differ based on the presence of labile C, and (iii) if community structure would shift as decomposition progressed. Residue was added to soil microcosms at rates that reflect field loads. Treatments were unleached straw (US), leached straw (LS), and leachate (L), plus an unamended control (C). Added substrates had δ¹³C values between 120% and 180% the native soil signature was 26%. Respiration was measured every 4 to 6 hours for the first 5 d, and weekly thereafter. Destructive sampling took place after 0.6, 1 .6, 1 5, 1 8. 50, and 80 d of incubation and microbial biomass '³C (MBC) and PLFAs were analyzed. The soluble component of ryegrass straw strongly influenced C mineralization and assimilation, as well as microbial community composition and dynamics. CO2 evolution rates and ¹³C signatures were similar in US and L during the first 3 d of incubation. Most soluble C from leachate was consumed during that time, indicated by the rapid decrease in δ¹³C value of CO2 evolved from L treatment. Substrate-derived C moved quickly into and through the microbial biomass. Distinct temporal shifts occurred in community composition. Early communities in amended soils were dominated by short and branched-chain PLFAs such as 15:Oa. Later samples contained more complex and longer PLFAs. 19:Ocy was an indicator for late succession communities in US and L, and 18:2w6,9 characterized late samples in LS. Soluble C affected when the temporal shift occurred in LS and L, communities shifted earlier than in US. Lipids were differentially enriched with ¹³C. Fungi, as indicated by 18:2w6,9, were more effective at incorporating substrate C into cellular lipids, as this was the most highly labeled of all PLFAs. Title: Linking soluble C to microbial community composition and dynamics during decomposition of ¹³C-labeled ryegrass Author: McMahon, Shawna K. Ryegrass residue consists of three main C fractions: readily available soluble C, intermediately available cellulose and hemicellulose, and slowly available lignin. Changes in chemical composition during decomposition influence rate of degradation as well as composition of the microbial community involved. Use of ¹³C-labeled plant material coupled with analysis of phospholipid fatty acids (PLEA) by isotope ratio mass spectrometry results in a powerful tool for linking microbial community structure and C cycling processes during decomposition. The objective was to investigate the role of soluble C in the decomposition of ryegrass straw. We wanted to determine (i) if the presence or absence of labile C in straw affects C mineralization by the microbial community, (ii) if community structure would differ based on the presence of labile C, and (iii) if community structure would shift as decomposition progressed. Residue was added to soil microcosms at rates that reflect field loads. Treatments were unleached straw (US), leached straw (LS), and leachate (L), plus an unamended control (C). Added substrates had δ¹³C values between 120% and 180% the native soil signature was 26%. Respiration was measured every 4 to 6 hours for the first 5 d, and weekly thereafter. Destructive sampling took place after 0.6, 1 .6, 1 5, 1 8. 50, and 80 d of incubation and microbial biomass '³C (MBC) and PLFAs were analyzed. The soluble component of ryegrass straw strongly influenced C mineralization and assimilation, as well as microbial community composition and dynamics. CO2 evolution rates and ¹³C signatures were similar in US and L during the first 3 d of incubation. Most soluble C from leachate was consumed during that time, indicated by the rapid decrease in δ¹³C value of CO2 evolved from L treatment. Substrate-derived C moved quickly into and through the microbial biomass. Distinct temporal shifts occurred in community composition. Early communities in amended soils were dominated by short and branched-chain PLFAs such as 15:Oa. Later samples contained more complex and longer PLFAs. 19:Ocy was an indicator for late succession communities in US and L, and 18:2w6,9 characterized late samples in LS. Soluble C affected when the temporal shift occurred in LS and L, communities shifted earlier than in US. Lipids were differentially enriched with ¹³C. Fungi, as indicated by 18:2w6,9, were more effective at incorporating substrate C into cellular lipids, as this was the most highly labeled of all PLFAs. Close

• 148. [Article] Population-based diallel analyses among nine historically recognized alfalfa germplasms

  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 published article is copyrighted by Springer ...

  Citation × Citation Citation Abstract Copy Title: Population-based diallel analyses among nine historically recognized alfalfa germplasms Author: Segovia-Lerma, A., Ray, I. M., Townsend, M. S., Murray, L. W. 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 published article is copyrighted by Springer and can be found at: http://link.springer.com/journal/122. Title: Population-based diallel analyses among nine historically recognized alfalfa germplasms Author: Segovia-Lerma, A., Ray, I. M., Townsend, M. S., Murray, L. W. 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 published article is copyrighted by Springer and can be found at: http://link.springer.com/journal/122. Close

• 149. [Article] Nature of inheritance, genotype-environment interaction and association of selected agronomic characters in crosses of winter X spring wheats (triticum aestivum L. em Thell)

  This investigation was motivated by the apparent increase in genetic variability resulting from the systematic combining of gene pools represented by winter and spring types of wheats. It was the objective ...

  Citation × Citation Citation Abstract Copy Title: Nature of inheritance, genotype-environment interaction and association of selected agronomic characters in crosses of winter X spring wheats (triticum aestivum L. em Thell) Author: Brajcich, P. This investigation was motivated by the apparent increase in genetic variability resulting from the systematic combining of gene pools represented by winter and spring types of wheats. It was the objective of this study to provide information regarding the nature of this genetic variability for nine agronomic characters in populations resulting from winter x spring crosses. Evaluations were made for: 1) the amount of total genetic variability; 2) the nature of the gene action making up this genetic variability using parent-progeny regression and combining ability analysis and 3) possible direct and indirect associations for traits which influence grain yield. Experimental populations which involved parents, Fl, F2 and backcross generations were grown at two locations where a spring and a winter environment could be utilized. At the winter site, the research was evaluated over a two year period. When the two experimental sites were compared, greater genetic diversity was observed at the spring site for maturity date, plant height, tillers per plant, kernel weight and grain yield. At the winter site, heading date, grain filling period, harvest index and kernels per spike were found to have more total genetic variation. From the expected mean square values, it would appear that the winter parents contributed more to the total genetic variation for most traits measured at both locations. A large genotype-location interaction was also noted suggesting that estimates of gene action and selection for adapted plant types can be done only at the specific winter or spring site. A large portion of the total genetic variation controlling the traits measured was due to additive gene action. However, at the winter site there was also a large influence of non-additive gene action associated with heading date, plant height, harvest index, tillers per plant, kernel weight, kernels per spike and grain yield. Of special interest was that at the winter site the most promising parental combinations could be predicted based on the general combining ability effects of the individual cultivars for each trait studied. Such data were not available for the spring site. Consistent and high correlations were observed between tillers per plant, kernels per spike and, to a lesser extent, kernel weight and grain yield at the winter location. Some negative associations were observed at the spring location between these traits and grain yield suggesting that yield component compensations were involved in the final expression of grain yield. The other characters measured did not reflect significant correlations with yield. When the correlation values were considered in terms of direct and indirect effects for specific traits, a large direct effect was noted for the three components and grain yield. The other traits exhibited small or no direct effects on grain yield but did have a slight influence on grain yield through tillers per plant, kernels per spike or kernel weight. Title: Nature of inheritance, genotype-environment interaction and association of selected agronomic characters in crosses of winter X spring wheats (triticum aestivum L. em Thell) Author: Brajcich, P. This investigation was motivated by the apparent increase in genetic variability resulting from the systematic combining of gene pools represented by winter and spring types of wheats. It was the objective of this study to provide information regarding the nature of this genetic variability for nine agronomic characters in populations resulting from winter x spring crosses. Evaluations were made for: 1) the amount of total genetic variability; 2) the nature of the gene action making up this genetic variability using parent-progeny regression and combining ability analysis and 3) possible direct and indirect associations for traits which influence grain yield. Experimental populations which involved parents, Fl, F2 and backcross generations were grown at two locations where a spring and a winter environment could be utilized. At the winter site, the research was evaluated over a two year period. When the two experimental sites were compared, greater genetic diversity was observed at the spring site for maturity date, plant height, tillers per plant, kernel weight and grain yield. At the winter site, heading date, grain filling period, harvest index and kernels per spike were found to have more total genetic variation. From the expected mean square values, it would appear that the winter parents contributed more to the total genetic variation for most traits measured at both locations. A large genotype-location interaction was also noted suggesting that estimates of gene action and selection for adapted plant types can be done only at the specific winter or spring site. A large portion of the total genetic variation controlling the traits measured was due to additive gene action. However, at the winter site there was also a large influence of non-additive gene action associated with heading date, plant height, harvest index, tillers per plant, kernel weight, kernels per spike and grain yield. Of special interest was that at the winter site the most promising parental combinations could be predicted based on the general combining ability effects of the individual cultivars for each trait studied. Such data were not available for the spring site. Consistent and high correlations were observed between tillers per plant, kernels per spike and, to a lesser extent, kernel weight and grain yield at the winter location. Some negative associations were observed at the spring location between these traits and grain yield suggesting that yield component compensations were involved in the final expression of grain yield. The other characters measured did not reflect significant correlations with yield. When the correlation values were considered in terms of direct and indirect effects for specific traits, a large direct effect was noted for the three components and grain yield. The other traits exhibited small or no direct effects on grain yield but did have a slight influence on grain yield through tillers per plant, kernels per spike or kernel weight. Close

• 150. [Article] Possible association of grain protein content, harvest index and biological yield in winter wheat populations

  A negative relation between grain protein content and grain yield is frequently observed in wheat (Triticum aestivum L. em Thell) i.e. as grain yield increases, grain protein decreases. It has been suggested ...

  Citation × Citation Citation Abstract Copy Title: Possible association of grain protein content, harvest index and biological yield in winter wheat populations Author: Costa, Jose Maria A negative relation between grain protein content and grain yield is frequently observed in wheat (Triticum aestivum L. em Thell) i.e. as grain yield increases, grain protein decreases. It has been suggested that the inverse relation between grain yield and protein is in part the result of developing high yielding semi-dwarf wheat cultivars with an increased harvest index. This investigation was undertaken to determine the nature of the possible association of grain yield and protein content as influenced by harvest index, biological yield, plant height and kernel weight in winter wheat populations grown in Oregon. Progenies derived from three crosses of winter wheat were solid-planted in two environments during two seasons. Phenotypic correlations showed a moderate negative association of grain protein content with both grain yield and harvest index. The magnitude of the genetic correlations suggested the presence of genetic relationships among these traits. Selection for harvest index among these crosses could cause a correlated reduction of grain protein content. To investigate if the relationships between grain protein content and selected plant growth traits were similar when grown under space-planted and solid seeded stands, progenies of two winter wheat crosses were evaluated during two seasons. Performance for grain yield and grain protein content was different under contrasting sowing densities as values were not correlated between sowing densities. This indicates the need to evaluate these traits in solid-seeded stands. Harvest index, as well as plant height and heading date, could be effectively selected under space-planted or solid seeded conditions. Associations among traits were reliably estimated in space-planted stands. To evaluate the effect on grain protein content when grain yield and harvest index are modified, the plant growth regulator Paclobutrazol was applied to selected winter wheat genotypes under field and greenhouse conditions. Paclobutrazol increased grain yield and harvest index values of all genotypes in the greenhouse, while only some genotypes improved these traits under field conditions. Grain protein content, however, remained unchanged. Higher grain yields were obtained in both greenhouse and field experiments. Title: Possible association of grain protein content, harvest index and biological yield in winter wheat populations Author: Costa, Jose Maria A negative relation between grain protein content and grain yield is frequently observed in wheat (Triticum aestivum L. em Thell) i.e. as grain yield increases, grain protein decreases. It has been suggested that the inverse relation between grain yield and protein is in part the result of developing high yielding semi-dwarf wheat cultivars with an increased harvest index. This investigation was undertaken to determine the nature of the possible association of grain yield and protein content as influenced by harvest index, biological yield, plant height and kernel weight in winter wheat populations grown in Oregon. Progenies derived from three crosses of winter wheat were solid-planted in two environments during two seasons. Phenotypic correlations showed a moderate negative association of grain protein content with both grain yield and harvest index. The magnitude of the genetic correlations suggested the presence of genetic relationships among these traits. Selection for harvest index among these crosses could cause a correlated reduction of grain protein content. To investigate if the relationships between grain protein content and selected plant growth traits were similar when grown under space-planted and solid seeded stands, progenies of two winter wheat crosses were evaluated during two seasons. Performance for grain yield and grain protein content was different under contrasting sowing densities as values were not correlated between sowing densities. This indicates the need to evaluate these traits in solid-seeded stands. Harvest index, as well as plant height and heading date, could be effectively selected under space-planted or solid seeded conditions. Associations among traits were reliably estimated in space-planted stands. To evaluate the effect on grain protein content when grain yield and harvest index are modified, the plant growth regulator Paclobutrazol was applied to selected winter wheat genotypes under field and greenhouse conditions. Paclobutrazol increased grain yield and harvest index values of all genotypes in the greenhouse, while only some genotypes improved these traits under field conditions. Grain protein content, however, remained unchanged. Higher grain yields were obtained in both greenhouse and field experiments. Close