Genetic variability for grain yield traits of five random-mating populations of Sorghum bicolor (L.) Moench

Abstract

Abstract Five random-mating sorghum populations were compared with two hybrids to determine amount and range of genetic variability for grain yield and yield components. Populations used represented varied contributions of adapted, temperate lines and converted, tropical exotic lines. Increased levels of genetic variability displayed by populations were generally associated with increases in the proportion of exotic, converted germplasm used in constructing the populations. Based on extent of genetic variability on a per plant basis, TP5R and TP13B offer most potential for improvement of grain yield. Highest variability for grain yield was displayed by TP5R and for seeds per panicle by TP13B. TP5R represented a population composed entirely of diverse converted sorghums. All populations displayed considerable genetic variability for flowering date and plant height, and little genetic variability for panicles per plant. Genetic variability was observed for seed weight in all but one population, TP13B. None of the populations exceeded hybrids for plot grain yield, reflecting the assemblage of desirable genes combined into hybrid combinations compared to the heterogeneous and heterozygous nature of random-mating populations. For the two cropping seasons over which the study was conducted, relative differences between populations and hybrids for grain yield were greater in 1980 than in 1981. Implications for potential improvement of populations with regard to grain yield and breeding needs for sorghum production in semi-arid environments are considered in relation to genetic variability contributed by component lines of populations.