Nodule functioning in trifoliate and pentafoliate mungbean genotypes as influenced by salinity

Two genotypes of mungbean differing in the leaf shape, K-851 (trifoliate) a nd a mutant (pentafoliate), were exposed to salinity (0, 2.5, 5, 10 dS m(-1 )) for 3, 6 and 9 d at flowering stage (40 - 45 d after sowing) to see the effect of salinity on nodule functioning. In both the genotypes, osmotic po tential (psi(s)) and relative water content (RWC) of nodules decreased sign ificantly, and proline content increased with increasing the salinity. The psi(s) of nodules was more decreased in the mutant than in genotype K-851, while reverse was true for RWC and proline accumulation. A remarkable incre ase in ethylene evolution was noticed from nodulated roots with the increas ing level and duration of salinity and was much higher in K-851. A sharp de cline in leghemoglobin content and acetylene reduction assay (ARA) of the n odules was observed with the salinity and this decrease was more marked in K-851 than the mutant. N content declined while Na+/K+ ratio and Cl- conten t increased significantly. The mutant maintained better N status but lower Na+/K+ ratio and Cl- content in nodules than K-851. Nodule dry matter also declined with salinity and the decrease was more expressed in K-851. Thus t he functioning of nodules in the mutant was better than in the genotype K-8 51 under stress conditions.