Plant growth promoting rhizobacteria in combination with plant growth regulators attenuate the effect of drought stress
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Abstract
The present study evaluates the effects of plant growth hormones (PGR), salicylic acid (SA), abscisic acid (ABA) and plant growth promoting rhizobacteria (PGPRs) Rhizobium pisi (DSM 30132 strain) applied alone and in combination, on pea (Pisum sativum L.) cv. Florida plants under well-watered and drought stressed conditions. Prior to sowing seeds were soaked for 5h in broth culture (10 cfu/ml) of Rhizobium pisi and SA /ABA. Seeds were soaked for 6h in distilled water, ABA, SA solutions. Plants were subjected to drought stress on 21 days old seedlings by withholding the supply of water at two different time points; for 4d (TP1) and for 8d (TP2). Rhizosphere soil of abscisic acid treated plants exhibited higher retention of soil moisture at TP1. Abscisic acid decreased the fresh and dry weight of plants under unstressed condition but increased the fresh weight as well as relative water content under drought stress. The response of Rhizobium and SA were at par. Rhizobium and SA ameliorated the adverse effects of drought stress more effectively than ABA. The Rhizobium inoculation reduced the stomatal conductance under unstressed condition but significantly increased stomatal conductance under drought stress at TP2. SA alone and in combination with Rhizobium stimulated the stomatal conductance under unstressed condition. Under drought stress, at TP1 all the treatments alone and in combination increased the relative water content (RWC) significantly over drought stressed plants. The FV/FM ratio was increased in SA treatment or in combination with SA, Rhizobium and ABA. It is inferred from the data that Rhizobium alone or in association with SA may be used to mitigate drought induced inhibition on plant growth and biomass. At TP1 the individual treatments of Rhizobium, ABA and SA exhibited better growth effect on pea plants. At TP2, Rhizobium assisted SA and ABA to mitigate drought induced adverse effects over control. The combined application of PGPR and PGRs can be substantiated more effectively on crop plants under drought stressed condition. Furthermore, integrating these approaches in the cropping system can contribute to maintaining soil fertility status, with better economic returns for future use.
TL;DRIt is inferred from the data that Rhizobium alone or in association with SA may be used to mitigate drought induced inhibition on plant growth and biomass and integrating these approaches in the cropping system can contribute to maintaining soil fertility status, with better economic returns for future use. (Semantic Scholar)