EVALUATION OF WHEAT PLANT PERFORMANCE FOR POPULATION IMPROVEMENT
Abstract
Genetic improvement of populations involves the increase in frequency of favorable genes for desired characteristics. This improves the population as a source of superior genotypes. All operations within such a system are often described by the general term, population improvement. There has been limited testing of the effects of intermating and recurrent selection techniques in wheat because of the difficulties in making the large number of crosses and the small amounts of seed produced. The objective of this study was to determine the effectiveness of multiple-trait, mass selection in the S$\sb0$ generation following intermating of a wheat population using a chemical hybridizing agent. Selection of single S$\sb0$ plants for several characters was generally not effective in improving the means of these characters measured in the S$\sb1$ and S$\sb2$. The lack of immediate gains in the population, however, does not necessarily reflect the gains in genetic potential from recombination within the population. The low effect on the population means may be due to the many compromises that must be made in the early cycles since there is a low frequency of genotypes with multiple desirable traits. A significantly wider range for most of the characters by the selections in this study as compared to the parents indicated the potential for improvement by selection. Kernel weight of the S$\sb0$ was significantly correlated with the S$\sb1$ and S$\sb2$ kernel weight. Kernel weight is largely of additive genetic control, therefore, progress in single plant selection for this and other additive characters may be effective. The difficulty remains in identifying the desirable characters in a variable environment. Larger gains per cycle of selection may be possible by delaying selection until the S$\sb1$ or S$\sb2$ generations when there is sufficient seed for larger selection units and replicated tests, but each generation of inbreeding would add a year to the cycle and reduce some of the advantages of intermating.
Degree
Ph.D.
Subject Area
Agronomy
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