Effect of plant growth promoting rhizobacteria (PGPR) and water stress on phytohormones and polyamines of soybean
Indian Journal of Agricultural Research
The effect of inoculation of three plant growth promoting rhizobacteria (PGPR) that is <italic>Rhizobium japonicum</italic>, <italic>Azotobacter chroococcum</italic> and <italic>Azospirillum brasilense</italic> and mixture of them on phytohormones and polyamines of soybean under different irrigation regimes was investigated. Drought stress induced by irrigation withholding until 40, 80 and 120 mm evaporation from evaporation pan. However seed bacterization of soybean was accompanied with 20 kg
... mpanied with 20 kg ha<sup>−1</sup> nitrogen. In addition, 20 and 100 kg ha<sup>−1</sup> nitrogen were considered as control treatments. The results showed that drought stress significantly decreased cytokinin, gibberellin and auxin accumulation in plant tissues. By contrast, drought stress led to increase in abscisic acid accumulation in soybean plants. Polyamines that are putrescine and spermidine increased due to drought stress and then decreased under severe drought stress. PGPR application had positive effect on growth promoting phytohormones compared to control treatment. However the highest accumulation of cytokinin, gibberellin and auxin was related to 100 kg ha<sup>−1</sup> nitrogen treatment. In case of abscisic acid PGPR application decreased its accumulation. Asignificant decrease as observed on polyamines accumulation when PGPRs were applied on stressed soybean plants.