Drought is one of the major constraints on agricultural productivity worldwide and is likely to further increase. Several adaptations and mitigation strategies are required to cope with drought stress. Plant growth promoting rhizobacteria (PGPR) could play a significant role in alleviation of drought stress in plants. These beneficial microorganisms colonize the rhizosphere/endo-rhizosphere of plants and impart drought tolerance by producing exopolysaccharides (EPS), phytohormones, 1-aminocyclopropane- 1-carboxylate (ACC) deaminase, volatile compounds, inducing accumulation of osmolytes, antioxidants, upregulation or down regulation of stress responsive genes and alteration in root morphology in acquisition of drought tolerance. The term Induced Systemic Tolerance (IST) was coined for physical and chemical changes induced by microorganisms in plants which results in enhanced tolerance to drought stresses. In the present review we elaborate on the role of PGPR in helping plants to cope with drought stress.

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Abstract:In this experiment, we evaluated different concentrations of three different chemical amendments viz, polyvinyl pyrrolidone (PVP), gum arabica, and sodium alginate for their ability to support growth and promote survival of Azotobacter vinelandii in nutrient broth during the storage. Azotobacter vinelandiiinoculated with PVP (4%) promoted highest cell population followed by gum arabica (0.5%) and sodium alginate (0.2%). The results of the present study clearly indicated that the 4% PVP probably gave higher cell population than other additives.