Abstract
ABSTRACTBoth the plant growth promoting rhizobacteria (PGPR) and plant growth regulators (PGR) exert beneficial effects on plant growth even under stress, but combined effect of both of them has not been evaluated yet. Present investigation was aimed to determine the responses of 2 chickpea varieties (differing in drought tolerance) to 3 PGPR viz. Bacillus subtilis, Bacillus thuringiensis and Bacillus megaterium and PGR (SA and Putrescine) on physiology of chickpea grown in sandy soil. The PGR, Salicylic acid (SA) and Putrescine (Put) were sprayed on the seedling 20 days after germination. Results revealed, synergistic effects of PGPR and PGR on chlorophyll, protein and sugar contents. Addition of PGR to PGPR inoculated plants assisted the plant in osmoregulation and amelioration of oxidative stresses and in induction of new proteins. Combined application of PGR and PGPR decreased lipid peroxidation more effectively but increased the leaf area. It is inferred that PGPR and PGR work synergistically to promote growth of plants under moisture and nutrient deficit condition of sandy soil. Since, SA induces Systemic Acquired Resistance (SAR) in plants hence the addition of SA along with PGPR may render the plant more productive and better tolerant to diseases/pathogen attack.
Highlights
Abiotic stresses are the most damaging for plants, among these the most destructive that effect the plants from physiological to molecular level is drought stress that limiting the growth and yield of crop plants ( Khan et al 2018; Pereira and Chaves 1995)
Antibacterial and antifungal activities of plant growth promoting rhizobacteria (PGPR) isolates which showed maximum increase (52% and 32%) in chlorophyll content in both the sensitive and tolerant varieties, respectively
PGPR are the main components of soil biodiversity and play a key role in enhancing soil nutrients and moisture content as they colonize the rhizosphere of plants and produce various substances including exopolysaccharides, phytohormones, aminocyclopropane- 1-carboxylate deaminase, induce accumulation of osmolytes, antioxidant enzymes and adopt root morphology to drought stress (Vurukonda et al 2016)
Summary
Abiotic stresses are the most damaging for plants, among these the most destructive that effect the plants from physiological to molecular level is drought stress that limiting the growth and yield of crop plants ( Khan et al 2018; Pereira and Chaves 1995). It is estimated that drought stress may cause a 50% loss in crop plants (Kasim et al 2013). Drought induces secondary stress e.g. oxidative stress, that can cause damage to proteins, lipids and nucleic acid in plants and can initiate lipid peroxidation (Hendry 2005; Nair et al 2008). Recent studies postulates that PGPR in association with PGR can help plants to cope with drought stress in much better way
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