Performance and Within‐Hybrid Variability of Three‐Way and Single Crosses of Grain Sorghum1

Abstract

Mean performance and within‐plot variability of parents and hybrids of grain sorghums [Sorghum bicolor (L.) Moench] were evaluated from the results of experiments conducted during 2 years in Iowa. Analyses of the data combined over years indicated that fertile single crosses and three‐way hybrids did not differ significantly for mean grain yield, 100‐seed weight, seeds/head, heads/plant, plant height, and days to midbloom. Mean within‐plot standard deviations for plant height and days to midbloom of the three‐way hybrids were significantly greater (P < 0.01) than those of single‐crosses, but the differences do not seem large enough to be important agronomically.Mean grain yields of single and three‐way crosses and within‐plot standard deviations for the other characters were not highly correlated. Neither the differences between parents of male‐sterile single crosses nor heterogeneity within parental lines was closely associated with level of variability within three‐way hybrids. Male‐sterile single crosses yielded significantly more (19%) than sterile lines as parents for the production of hybrid seed. Superiority of the single crosses resulted primarily from larger numbers of seeds/head.