The physiological and biochemical responses of directly seeded and transplanted maize (Zea mays L.) supplied with plant growth-promoting rhizobacteria (PGPR) under water stress

Abstract

The purpose of the present study was to investigate the effect of plant growth-promoting rhizobacteria(PGPR) on physiological and biochemical properties of maize (Zea mays L.) in different cultivation methods under water stress. The experiment was carried out as split-plot design including water stress (well-watered, mild stress, and severe stress) as main plot and also cultivation (transplanting and direct seeding) and PGPR application (uninoculated and inoculated with Pseudomonas putida) as subplots.Water stress decreased biological and kernel yield. In direct seeding and no Pseudomonas application, severe stress decreased the kernel yield by 37% compared to the well-watered condition. Water stress resulted in significant reduction of chlorophyll content. However, it was increased by Pseudomonas application. In transplanting plants, well-watered and Pseudomonas application increased the chl. a+b by 41% in comparison with severe stress and no Pseudomonas application. Catalase (CAT) and superoxide dismutase (SOD) activities were gradually raised by increasing the water stress. In transplanted plants inoculated with Pseudomonas, severe stress decreased relative water content (RWC) by 23% compared to well-watered plants. In transplanted plants inoculated with Pseudomonas, severe stress increased Malondialdehyde (MAD) by 46% compared to well-watered plants. Total phenolic content (TPC) and total flavonoid content (TFC) increased by mild water stress and decreased by severe water stress. In directly seeded plants inoculated with Pseudomonas, mild water stress increased TPC by 11% compared to well-watered condition. Compared to well-watered treatment, 54% increases were observed in TFC by mild stress in transplanted plants treated with Pseudomonas. Transplanting and Pseudomonas was concluded to alleviate the adverse effects of water stress on physiological and biochemical traits of maize.