Gera, RajeshMondal, Hemanta Kumar2017-12-132017-12-132017http://krishikosh.egranth.ac.in/handle/1/5810037470Mothbean, clusterbean and mungbean are the economically important abiotic stress-tolerant kharif legumes grown mainly in hyper-arid zone of Rajasthan in India. Inoculation of high abiotic stress-tolerant strains of rhizobia with PGP traits improves the nitrogen fixation as well as plant biomass yield of legumes under stress conditions. Simultaneously, molecular diversity of abiotic stress-tolerant nodule rhizobia gives better probability to obtain efficient rhizobial bioinoculants. In the present study, a total of 201 rhizobial isolates were retrieved from 101 different nodule samples collected from various locations of four districts viz.Churu, Bikaner, Jaisalmer and Barmer situated under hyper-arid zone of Rajasthan, India. Combined abiotic stress-tolerance experiment revealed that 38 rhizobial isolates were tolerant to 30% PEG and 40oC, while only 16 isolates showed high drought tolerance of 40% PEG concentartion and high temperature tolerance of 45oC. All the 54 stress-tolerant isolates possessed dinitrogen fixation ability with different degrees of efficacy. Stress-tolerant rhizobial isolates also harboured multiple plant growth promoting traits like phosphate solubilization, IAA production, bacteriocin production and ACC deaminase activity. All the 54 abiotic stress-tolerant rhizobial isolates showed amplification of nodC and nifH genes. ARDRA analysis of 16S rDNA of mothbean, clusterbean and mungbean rhizobial isolates using restriction enzymes MspI and HaeIII showed an enormous diversity among rhizobial isolates. Mothbean, clusterbean and mungbean rhizobial isolates formed two major clusters with different sub-clusters and the divergence among them started at 48, 57 and 59% level of similarity coefficient. A total of 11 promising abiotic stress-tolerant rhizobial isolates of mothbean, clusterbean and mungbean were evaluated under stress conditions. Three rhizobial isolates MoCh17b, ClJs74b and MuJs52b showed better performance in nodulation efficiency and plant growth parameters as compared to other treatments under temperature stress in Leonard jars. Four rhizobial isolates MoCh17b, ClBr87a, MuJs52b and MuJs72a also performed better nodulation efficiency and plant growth parameters grown at different soil moisture regime of 100, 50 and 25% field capacity (FC) in pots. Abiotic stress-tolerant rhizobial isolates were identified as Ensifer sp, Rhizobium pusense, Rhizobium sp LM-5 or Agrobacterium fabrum (syn. R. radiobacter).ennullThesis