Comparisons of Agronomic Characteristics in C0 and C4 of IAP3BR(M) Random-Mating Grain Sorghum Population1
- T. F. Kwolek,
- R. E. Atkins and
- O. S. Smith2
Agronomic performance and genetic variability of the random-mating sorghum [Sorghum bicolor (L.) Moench] population IAP3BR(M) were evaluated after four cycles of mass selection for large seed (g/100 seed). Sixty S1 families chosen at random from both the initial cycle (C0) and the fourth cycle (C4) of the population were grown in 2 yr in central, southern, and northwestern Iowa. Estimates of genotypic variance (σ2g) among S1 families were not significantly different to C0 and C4 for g/l00 seed, seeds/panicle, and plant height. Estimates differed significantly, and they were larger in C4, for grain yield, panicles/plant, and days to midbloom. Heritability estimates for C0 and C4 for each character most often were of similar magnitude. The highest heritabilities were for g/l00 seed, followed by seeds/panicle, grain yield, and panicles/plant. Mass selection was effective for increasing seed size in IAPJBR. Undesirable changes in the means for grain yield, seeds/panicle, and panicles/plant indicated that mass selection for seed size was not effective in improving the overall merit of this population. Means and components of variance, together with estimates of response to selection and correlated response among characters, indicated that SI family testing for grain yield may serve better than mass selection for 100-seed weight for overall improvement of the population beyond the fourth cycle.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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