Combining Ability Effects on Nitrogen Fixation Traits in Mungbean [Vigna Radiata (L.) Wilczek]

Combining ability analysis for nodule fresh weight and total nitrogen was carried out in an 11 x 11 diallel in mungbean [Vigna radiata (L.) Wilczek] grown on N-free agar slants in symbiosis with cowpea Rhizobium strain M 05 of M 200 (both CCA). General combining ability (gca) and specific combining ability (sca) mean squares were significant for these two nitrogen fixation traits. Parents K-851, PS-7 and PIMS-2 showed significantly positive gca effects for both the nitrogen fixation traits and would be useful as parents in breeding programme. The Rhizobium symbionts did not affect the relative magnitudes of gca and sca variances, but there was some effect on the magnitudes and in some cases the direction of gca and sca effects.