Abstract

Combining ability estimates were studied for pod shattering and other agronomic traits in eight  parental soybean genotypes of different pod shattering group namely: susceptible to pod shattering, moderately resistant to pod shattering were crossed in a 4 x 4 North Carolina mating design II to generate 16 crosses, due to missing stands encountered in some crosses, 9 successful F_1S hybrids were obtained in the present study and evaluated along with the parents to estimate the mode of gene action controlling pod shattering in soybean and the combining ability for pod shattering and other agronomic traits in soybean. The mean square from the analysis of variance for the ten traits measured showed highly significant differences (p<0.01) among the genotypes. This has demonstrated the existence of genetic variability among soybean genotypes with pod shattering under additive gene action. TGX1955-10E, NG/AD/11/08/023 and NG/SA/07/100 were good general combiners for resistance to pod shattering, plant height, days to 50% flowering and days to maturity while NG/MR/11/11/060, NGBOO/08, TGX1740-1F and NG/SA/07/055 are good general combiner for number of seeds/ pod, pod length, hundred seed weight and grain yield. NG/SA/07/100 x TGX1740-1F, NG/MR/11/11/060 x NGBOO129 and NG/MR/11/11/060 x NG/AD/11/08/023 had positive specific combining ability effects for number of branches/ plant, number of pods/plant, pod length, number of seeds/pod, hundred seed weight and grain yield.  NG/MR/11/11/060 X NG/SA/07/055had negative SCA effects for plant height. This implied that these hybrids performed better than the parents GCA effects. This suggests that the cross combination can be advanced for selection in later generation.

Key words: Combining ability effects, soybean genotypes, pod shattering, Samaru.