Genetics of grain amaranths : 4. Variation and early generation response to selection in Amaranthus cruentus L

Two landrace populations of Amaranthus cruentus L. were crossed to generate F2 populations for quantitative genetic analyses of variation. Evidence for significant inbreeding depression in comparisons of F1 and F2generation means suggested some role of nonadditive gene action for days to first anthesis, leaf length, leaf width, petiole length, plant height, panicle length, and panicle weight. A pooled F2 population was subjected to bidirectional mass selection for time of first anthesis (two cycles) and leaf length (one cycle). Responses to selection were asymmetrical and the second cycle response for anthesis time was smaller than for the first cycle. Overall, selection gains were significant and gave estimates of heritability in the range of 0.35 to 0.66 for anthesis time and 0.08 to 0.19 for leaf length. This suggested a large additive term in the total genetic variance especially for anthesis time where early and late flowering selection lines diverged by 20.5 days.Correlations between the selected traits (anthesis time, leaf length) and single plant yield or yield components were also studied to evaluate correlated responses to selection. Selection for optimal flowering time in amaranth cultivation areas is very likely to result in rapid yield improvement.