Symbiotic efficiency of pigeonpea (Cajanus cajan (L.) Huth) with different sources of nitrogen

Abstract

AbstractPigeonpea is an important grain legume. It contributes to the improvement of soil fertility through biological nitrogen (N) fixation. However, the symbiotic efficiency of pigeonpea with native soil rhizobia has not been determined adequately. This study was designed to determine the variation in the N fixation ability of pigeonpea inoculated with the native rhizobia. Forty soil samples were collected from diverse locations across South Africa and used for inoculating pigeonpea seed. Each pigeonpea genotype was inoculated separately with each soil sample and raised in a nitrogen-depleted growth medium in the greenhouse. A split-plot experimental design was used in the study. Several N fixation variables of pigeonpea were measured. There was >40.0% difference in the number of nodules between genotypes ‘Ex-PP-MD-321’ and ‘Mpuma-B-Spot’ but the nodule dry weight between the two genotypes was >80.0%. In contrast, the heaviest dry shoots (0.4513 g), weighed 52.0% heavier than those that were observed for ‘Mpuma-B-Spot’. Pigeonpea showed differential N fixation ability with the nodules, suggesting that there was potential to select for optimum host × rhizobial isolate combinations for the process and to expand the production area of the crop.