A comparison of parent-hybrid performance in grain sorghum

Abstract

A study was conducted to compare and correlate the performance of parents and hybrids in early and late generations of grain sorghum and to evaluate the combining abilities of selections and four male-sterile lines. A cross was made between Combine 7078 and Combine White Feterita and F₂, F₄ and F₆ populations were established. In each of these three generations, 15 selections were made and each of these selections was crossed to four male-sterile lines, A3197, A398, A378 and A3048. All parents and their hybrids in each generation were grown in 1964 and 1965 and data were recorded on days to 50% bloom, plant height, head exsertion [sic], head length, head weight, grain yield, threshing percentage, bushel weight and weight of 100 seed. Phenotypic correlation coefficients were calculated between parents and hybrids in each generation, within each A-line, overall in three generations, for each year and for all characteristics studied. Analyses of variance and Duncan's multiple range tests were used to determine significance of differences. The correlations between parents and hybrids were higher in the F₄ and F₆ generations than in the F₂ generation for most of the characteristics studied. Parent-hybrid correlations were very low for threshing percentage. Correlations calculated in the two years were similar for many characteristics. Hybrid vigor was evident in most of the characteristics studied, both in early and late generations. Early generation pollinators and hybrids were higher yielding and later maturing than were late generations. Among the A-lines, A378 had the best general combining ability for yield and most of the other characteristics. Hence, combining ability for yield was also related with the combining ability of other characteristics in this experiment. The individual correlations between parents and hybrids were comparatively high in A3197 and A378 hybrids. These two steriles ranked the pollinators for several characteristics more distinctly than A398 and A3048.