Recurrent selection for maturity, seed yield and percent seed protein in soybeans (Glycine max (L.) Merr.); using genetic male sterility

Hongjun Xu, Purdue University

Abstract

Four cycles of recurrent selection for early maturity, high seed yield, and high percent seed protein in soybean (Glycine max (L.) Merr.) were evaluated using genetic male sterility (ms2) to facilitate intermating. The main objectives of this study were to determine the phenotypic responses of maturity, seed yield, and percent protein in seeds, to determine the relationship between the selected trait and the non-selected traits within the populations in different cycles, and to study the effectiveness of this recurrent selection program based on S$\sb0$ individual plant performance. Each recurrent selection cycle included two stages, intermating and S$\sb0$ evaluation and selection. Intermating was by bees in a bulk planting of seeds from selected plants; seeds were harvested only from male sterile plants in the bulk. Evaluation and selection were based on space-planted S$\sb0$ individual plant performance. 'Beeson'ms2ms2 X 'Corsoy' F$\sb2$ seeds (40%), 'Wells'ms2ms2 X 'Hark' F$\sb2$ seeds (40%), and a high protein line, CX602-107-1-2 seeds (20%) were mixed to form the original intermating population. A selection intensity of 20% in three populations, MAT, YLD, and PRO, respectively was for early maturity, high seed yield, and high percent seed protein. Progress was measured relative to the check cultivar 'Century'. For the first four cycles plants in the MAT population averaged 2.7 d per cycle earlier in maturity than the cultivar 'Century' and yielded 9.1 g per cycle less than Century. The YLD population increased 11.1 g per cycle in mean yield while maturity shifted 3.6 d per cycle later than Century. The PRO population increased 0.8 percentage points per cycle in seed protein content and decreased 3.2 g per cycle in seed yield. In this population maturity was delayed 1.8 d per cycle and seed oil decreased 0.5 percentage points per cycle compared to Century. The results also showed a very consistent inverse relationship between protein and oil in soybean seed in all three populations. There were no decreases in variability for the selected traits and the non-selected traits after four cycle of selection in all three populations. Random mating occurred in the intermating stage in all populations. The results of competition tests in this study indicated the male-sterile plants in the S$\sb0$ evaluation test had no effect on selection for the high heritability trait maturity, the medium heritability trait percent seed protein, or the low heritability trait seed yield.

Degree

Ph.D.

Advisors

Wilcox, Purdue University.

Subject Area

Agronomy|Genetics

COinS