Estimation of Indole Acetic Acid and Phosphate Solubilisation by the Yeasts Isolated from the Leguminous Crops

Abstract

Aim: The present study was aimed to estimate the quantity of IAA production and Phosphate solubilisation by the isolated yeasts from the leguminous crops. Place and Duration of Work: The experiments were carried out in the Department of Agricultural Microbiology, University of Agricultural Sciences, GKVK, Bengaluru during 2019-2020. Methodology: Yeasts were isolated from the leguminous crops such as Red gram, Cowpea, Green gram, Black gram and Bengal gram. Thirty-five yeast isolates were obtained using four media and were subjected to IAA production test and Phosphorus solubilisation by Spectrophotometry method. All the yeast isolates were subjected to the temperature tolerance test at 25, 30, 35 and 40°C. Results: Yeast isolate, CP15SI21 has found to produce the highest IAA under in vitro conditions 30.50 μg/ml and the lowest was found to be 17.16μg/ml by yeast isolate BG20SI29. 24 yeast isolates were found to produce above 20 μg/ml. In the case of Phosphate solubilisation highest was observed in GG7SI9 (25.70 mg/l) and lowest in BG6SI8 (1.20 mg/l). Seven isolates showed Phosphate solubilisation above 10 mg/l. At 35°C all the yeast isolates have shown very good growth compared to other lower temperatures. All the yeast isolates were found to grow in the media supplemented with micronutrients such as zinc and potassium. Conclusion: Our study highlights the potential of yeasts isolated from the leguminous crops that can help in plant growth promotion as the yeast isolates are capable of producing higher amounts of IAA. Some of the yeast isolates can solubilise phosphate under in vitro conditions which in turn helps in the utilization of unavailable P from soils thereby improves plant growth and tolerance to a higher temperature can alleviate abiotic stress.