Khanna, VeenaJotshana Kumari2020-01-162020-01-162019http://krishikosh.egranth.ac.in/handle/1/5810140530The present investigation was undertaken to access the effect of rhizobial isolates on plant growth and symbiotic parameters in Lucerne (Medicago sativa L.).Forty rhizobial isolates were identified and characterized culturally, morphologically, biochemically and found belonging to genera Rhizobium. The isolates were functionally characterized on the basis of phosphate solubilization, Indole acetic acid, siderophore, cyanide and gibberellic acid production. Indole acetic acid production ranged from 2.6 -77.7 μg/ml in presence of tryptophan after 3 days of incubation and increased to 2.9-101.7 μg/ml on 5th day.The range of PSI (Phosphate solubilization index) was 13-17 mm with highest solubilizing index shown by LNR-6, LNR-20, LNR-23 and LNR-39 (17mm).Twenty eight of the forty isolates were able to produce siderophore as evidenced on Chrom-azurol-S-agar, maximum catecholate type siderophore produced by LNR-39 (43.4 μg/ml). 57.5% isolates produced HCN out of which 13 % were strong and 39.1% were moderate producers. The gibberellic acid production ranged from 41.2 -96.6 μg/ml with LNR-39 (96.6 μg/ml) being the potent gibberellic acid producer. The study carried out showed that isolates LNR-2,LNR-4, LNR-6, LNR-22, LNR- 32 and LNR-39 exhibited growth and functionality traits which were at par, hence they were selected for field trail. The field experiment revealed enhanced stem and root length,dry weight of nodules, nitrogen content, leghemoglobin and chlorophyll content , green fodder yield under Rhizobium treatment. Thus, the present study revealed that treatment with Rhizobium LNR-39 and treatment LNR-4 were effective for plant growth promotion and enhanced symbiotic effeicency in Lucerne.ennullThesis