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• 31. [Article] The influence of plant densities on gene action estimates and associations in seven winter wheat parents and their F₂ progeny

  The F₂ progeny from a diallel cross involving seven winter wheat parents along with the parents were grown at the Hyslop Agronomy Farm near Corvallis, Oregon to determine the influence of three plant densities ...

  Citation × Citation Citation Abstract Copy Title: The influence of plant densities on gene action estimates and associations in seven winter wheat parents and their F₂ progeny Author: Saini, Surinder Kumar The F₂ progeny from a diallel cross involving seven winter wheat parents along with the parents were grown at the Hyslop Agronomy Farm near Corvallis, Oregon to determine the influence of three plant densities on gene action estimates for yield and its primary components. The plant densities were designed to provide different levels of competitions involving solid, six and 12 inch spacing within the rows with one foot spacing between the rows. Gene action estimates were obtained by the combining ability analysis as well as narrow sense heritability estimates. In addition, path-coefficient analysis was utilized to investigate the direct and indirect associations of the primary components of yield under different stresses of competition resulting from the changes in population densities. The morphological characters measured were 1) total yield per plant, 2) kernel weight 3) number of kernels per spikelet, 4) number of spikelets per spike, 5) tiller number and 6) plant height. A small additive gene action for yield was noted in the six inch spacing while additive gene action effects could not be detected in the 12 inch and solid plantings. Yield being a complex trait seems to be affected by the environmental changes resulting from different plant densities. Consistent general combining ability estimates were observed for kernel weight and plant height in all the plant densities, indicating a small genotype-environment interaction. In the spaced plantings additive gene action estimates were obtained for tiller number and spikelets per spike while there was no evidence of additive gene effects in the solid planting. No additive gene action was noted for kernels per spikelet in the 12 inch planting while six inch and solid plantings revealed considerable genetic variability. These results would suggest that the genotypes are susceptible to environmental fluctuations for the traits tiller number, spikelets per spike and kernels per spikelet. The correlation coefficients reveal that in spaced plantings tiller number, spikelets per spike and kernels per spikelet are significantly and positively related to yield. In the solid seeding only spikelets per spike was significantly associated to yield. When the four variables were considered in terms of their associations with yield it was observed in the F₂ that in spaced plantings all the four components of yield have direct positive influence on yield. In the solid seedings however, spikelets per spike and kernels per spikelet had high positive direct effects on yield while tiller number and kernel weight showed a negative direct influence on yield. The data revealed that spikelets per spike and kernels per spikelet are the most important traits contributing towards yield. However, the results obtained with correlation coefficients indicate that a negative association existed between these two traits as well as between kernels per spikelet and tiller number suggesting the possible existence of a biological limitation between these components of yield. The results indicate that a breeding program with emphasis on the selection of plants in competitive conditions in the early generations may make the selection work more efficient. Moreover, increases in yield which considers each of the components separately or in combination of two or more would offer the most promise. By this procedure the breeder would take advantage of the large amount of additive genetic variances associated with each of the components and at the same time take into consideration any biological limitations which may exist. Title: The influence of plant densities on gene action estimates and associations in seven winter wheat parents and their F₂ progeny Author: Saini, Surinder Kumar The F₂ progeny from a diallel cross involving seven winter wheat parents along with the parents were grown at the Hyslop Agronomy Farm near Corvallis, Oregon to determine the influence of three plant densities on gene action estimates for yield and its primary components. The plant densities were designed to provide different levels of competitions involving solid, six and 12 inch spacing within the rows with one foot spacing between the rows. Gene action estimates were obtained by the combining ability analysis as well as narrow sense heritability estimates. In addition, path-coefficient analysis was utilized to investigate the direct and indirect associations of the primary components of yield under different stresses of competition resulting from the changes in population densities. The morphological characters measured were 1) total yield per plant, 2) kernel weight 3) number of kernels per spikelet, 4) number of spikelets per spike, 5) tiller number and 6) plant height. A small additive gene action for yield was noted in the six inch spacing while additive gene action effects could not be detected in the 12 inch and solid plantings. Yield being a complex trait seems to be affected by the environmental changes resulting from different plant densities. Consistent general combining ability estimates were observed for kernel weight and plant height in all the plant densities, indicating a small genotype-environment interaction. In the spaced plantings additive gene action estimates were obtained for tiller number and spikelets per spike while there was no evidence of additive gene effects in the solid planting. No additive gene action was noted for kernels per spikelet in the 12 inch planting while six inch and solid plantings revealed considerable genetic variability. These results would suggest that the genotypes are susceptible to environmental fluctuations for the traits tiller number, spikelets per spike and kernels per spikelet. The correlation coefficients reveal that in spaced plantings tiller number, spikelets per spike and kernels per spikelet are significantly and positively related to yield. In the solid seeding only spikelets per spike was significantly associated to yield. When the four variables were considered in terms of their associations with yield it was observed in the F₂ that in spaced plantings all the four components of yield have direct positive influence on yield. In the solid seedings however, spikelets per spike and kernels per spikelet had high positive direct effects on yield while tiller number and kernel weight showed a negative direct influence on yield. The data revealed that spikelets per spike and kernels per spikelet are the most important traits contributing towards yield. However, the results obtained with correlation coefficients indicate that a negative association existed between these two traits as well as between kernels per spikelet and tiller number suggesting the possible existence of a biological limitation between these components of yield. The results indicate that a breeding program with emphasis on the selection of plants in competitive conditions in the early generations may make the selection work more efficient. Moreover, increases in yield which considers each of the components separately or in combination of two or more would offer the most promise. By this procedure the breeder would take advantage of the large amount of additive genetic variances associated with each of the components and at the same time take into consideration any biological limitations which may exist. Close

• 32. [Article] Sulfhydryl and disulfide changes in young wheat seedlings during vernalization

  A study of the SH and SS content levels during vernalization of wheat was made. In order to carry out the study, a rapid analytical technique was worked out which allowed fast sequential analyses of the ...

  Citation × Citation Citation Abstract Copy Title: Sulfhydryl and disulfide changes in young wheat seedlings during vernalization Author: Ellis, Robert William A study of the SH and SS content levels during vernalization of wheat was made. In order to carry out the study, a rapid analytical technique was worked out which allowed fast sequential analyses of the samples of wheat tissue. Two techniques were used: a) an amperometric titration method and b) a fluorescence quenching method. The amperometric titration method consisted of adding aliquots of samples of wheat tissue homogenate to the system and noting the decrease in current, due to a tie-up of Ag⁺ by the SH groups of the sample. The system consisted of a rotating platinum electrode connected to a mercury-mercuric oxide reference cell. The supporting electrolyte was a 0.14M solution of tris at pH 7.4. The fluorescence quenching method consisted of adding aliquots of sample to a solution of fluorescien mercuric acetate (FMA) in a 1N NaOH media. The SH and SS groups reacted with FMA in a one:one ratio. The reacted FMA was unable to fluoresce, thus making possible a quantitative assay for SH and SS groups in solution. Red Bobs, a spring wheat, and Elgin, a winter wheat, were grown in the dark at 3° C. and at 20° C. The SH and SS contents of the shoots were measured throughout a period of five weeks in the group grown at 3° C. and a period of 48 hours in the group grown at 20° C. The results of the analyses showed that the SH, SS, and SH+SS contents based on fresh weights were present in greater quantities in the tissues of Red Bobs grown at 20° than in the Elgin tissues grown at 20°. The high SH and SS concentrations present in the warm-grown Red Bobs tissues were due to a high concentration of protein extracted from that tissue. The SH, SS, and SH+SS contents per fresh weight were quite similar in the cold-grown tissues of both varieties during the growth period. These constituents present in the cold-grown tissues occurred in quantities that were less than those found in warm-grown Red Bobs tissues and greater than those present in the warm-grown Elgin tissues. Both varieties grown at both temperatures showed a similar decrease in SH and SS contents based on fresh weights as maturation progressed. The analyses indicated that SH, SS, and SH+SS contents based on protein levels were similar in Elgin and Red Bobs tissues grown at 20°. Both varieties grown at 3° contained greater concentrations of SH, SS, and SH+SS groups based on protein levels than those present in the tissues grown at 20°. The Elgin tissues at 3° underwent a fluctuation of these values as growth progressed, while the Red Bobs tissues at 3° maintained relatively constant levels of SH, SS, and SH+SS contents based on protein levels present during the growth period. It was concluded that the levels or patterns of SH and SS groups in young spring and winter wheat shoots were not correlated with the capacity of these plants to flower. Title: Sulfhydryl and disulfide changes in young wheat seedlings during vernalization Author: Ellis, Robert William A study of the SH and SS content levels during vernalization of wheat was made. In order to carry out the study, a rapid analytical technique was worked out which allowed fast sequential analyses of the samples of wheat tissue. Two techniques were used: a) an amperometric titration method and b) a fluorescence quenching method. The amperometric titration method consisted of adding aliquots of samples of wheat tissue homogenate to the system and noting the decrease in current, due to a tie-up of Ag⁺ by the SH groups of the sample. The system consisted of a rotating platinum electrode connected to a mercury-mercuric oxide reference cell. The supporting electrolyte was a 0.14M solution of tris at pH 7.4. The fluorescence quenching method consisted of adding aliquots of sample to a solution of fluorescien mercuric acetate (FMA) in a 1N NaOH media. The SH and SS groups reacted with FMA in a one:one ratio. The reacted FMA was unable to fluoresce, thus making possible a quantitative assay for SH and SS groups in solution. Red Bobs, a spring wheat, and Elgin, a winter wheat, were grown in the dark at 3° C. and at 20° C. The SH and SS contents of the shoots were measured throughout a period of five weeks in the group grown at 3° C. and a period of 48 hours in the group grown at 20° C. The results of the analyses showed that the SH, SS, and SH+SS contents based on fresh weights were present in greater quantities in the tissues of Red Bobs grown at 20° than in the Elgin tissues grown at 20°. The high SH and SS concentrations present in the warm-grown Red Bobs tissues were due to a high concentration of protein extracted from that tissue. The SH, SS, and SH+SS contents per fresh weight were quite similar in the cold-grown tissues of both varieties during the growth period. These constituents present in the cold-grown tissues occurred in quantities that were less than those found in warm-grown Red Bobs tissues and greater than those present in the warm-grown Elgin tissues. Both varieties grown at both temperatures showed a similar decrease in SH and SS contents based on fresh weights as maturation progressed. The analyses indicated that SH, SS, and SH+SS contents based on protein levels were similar in Elgin and Red Bobs tissues grown at 20°. Both varieties grown at 3° contained greater concentrations of SH, SS, and SH+SS groups based on protein levels than those present in the tissues grown at 20°. The Elgin tissues at 3° underwent a fluctuation of these values as growth progressed, while the Red Bobs tissues at 3° maintained relatively constant levels of SH, SS, and SH+SS contents based on protein levels present during the growth period. It was concluded that the levels or patterns of SH and SS groups in young spring and winter wheat shoots were not correlated with the capacity of these plants to flower. Close