Beneficial traits of endophytic bacteria from field pea nodules and plant growth promotion of field pea

Endophytic bacteria from nodules of field pea (Pisum sativum L.) being grown in CCS Haryana Agricultural University farm were isolated. A total of 60 endophytic bacteria from surface sterilized nodules of field pea were isolated. Screening for the presence of beneficial traits showed that 63.3% of field pea nodule endophytes were promoting root growth of pea seedlings in water agar root growth promotion assay. A total of 38.3% of endophytic isolates were phosphate solubilizers, 83.3% were ammonia producers and only 32% of isolates were producing organic acid. Root growth assay showed that nodule endophytes PNE17 and PNE26 are better root growth promoters; PNE15, PNE24 are best P solubilizers; PNE5, PNE15 are best ammonia producers and PNE17 and PNE27 are the best organic acid producers. Based on the presence of multiple beneficial traits, selected 41 endophytic nodule isolates were inoculated together with Rhizobium leguminosarum biovar viciae strain PS 43 in field pea under pot culture conditions and showed enhanced plant growth, nodulation and nitrogen fixing parameters in field pea. Highest shoot dry weight and shoot N contents was observed in plants inoculated with PNE17 followed by PNE26, PNE77 and PNE15 along with Rhizobium. Symbiotic ratio (SR) based on shoot N contents varied from 0.70 to 3.10 indicating vide variation in effectivity. Endophytic isolate PNE 15, PNE 22, PNE 26 and PNE 77 showed SR ratio more than 2.0, while isolate PNE 17 was the most effective endophyte with SR more than 3.0.