Combining ability of introduced sorghum parental lines for major morpho-agronomic traits

Abstract

Sorghum (Sorghum bicolor) is the dominant crop in the arid and semi-arid tropics, where drought seriously affects its production. The use of improved cultivars, particularly hybrids, was found to be the major component of the integrated approach of mitigating the drastic effect of drought. Thus information on the combining ability of different lines is very pertinent to choose the best parents and to set the suitable breeding method. Fifty-four F 1 hybrids were developed by crossing 18 pollinator parents with three standard females following the Design II mating scheme. The hybrids were evaluated at two drought prone locations, Melkassa and Shoa Robit in Ethiopia, using randomized complete block design. This research was conducted with the objectives of estimating the combining ability of the parents with respect to yield and yield-related parameters linked to drought tolerance, and to determine the mode of gene action for drought tolerance traits. The Statistical Analysis Systems (SAS) was used to analyze the data. Combined analysis of variance revealed significant variation among entries for panicle length, seed weight, plant height, time to maturity and panicle exsertion. The entry × location effect was significant for the other observed traits thus signifying differential response of the genotypes in each of the locations. General combining ability (GCA) for plant height, panicle exsertion, panicle length, grain yield and seed weight was significant among male parents indicating the prevalence of additive gene action in determining these traits. The GCA for females was not significant for any of the observed traits except panicle exsertion. However, P9517A appeared to be marginally superior to the other two females in producing high-yielding hybrids having relatively higher panicle weights and panicle yields as well as in possessing larger numbers of green leaves at maturity, a trait termed as stay-green. The male parents exhibited considerable variability for most of the traits considered. Specific combining ability (SCA) effects were not significant for any traits observed.