Scrutinizing of rhizobacterial isolates for improving drought resilience in maize (Zea mays)

Abstract

Food security due to scarcity of water to field crops is major concern now a days due to stress environments. A growth room trial was performed to screen potential bacterial inoculants for improving growth and physiology of maize (Zea mays L.) under water scarcity. Thirty fast growing rhizobacteria were isolated from rhizosphere of maize, cultivated in arid and semiarid areas of the province (Punjab). Isolates were evaluated for their plant growth promoting characters and drought tolerance, at various moisture levels developed in-vitro by using 0, 5, 10, 15, 20 and 25% polyethylene glycol (PEG-6000). Nine most efficient isolates (LK-2, LK-7, LK-9, LK-13, LK-16, LK-18, LK-21, LK-24, LK-29) were selected, having potential ability to survive in water stressed condition and were tested further in a jar experiment for their role in morpho-physiological improvements in maize seedlings, grown at different drought levels (100, 70 and 40% field capacity (FC). Results depicted that inoculation significantly (P≤0.05) enhanced root/shoot biomass & root/shoot ratio, chlorophyll a and b, starch content, soluble sugars, relative water content, photosynthetic rate, water use efficiency and stomatal conductance. Overall, isolate LK-13 and LK-16 were found more prominent in inducing drought tolerance in seedlings as compared to other isolates and uninoculated control. Identification of isolates through 16sRNA sequencing confirmed the both strains (LK-13 and LK-16) belong to Bacillus spp. Inoculation of maize seeds with rhizobacteria as plant growth promoting rhizobacteria enhanced growth and physiology of maize. So, inoculation of PGPR could be a potential approach for enhancing drought resilience in maize (Zea mays L.).