Effective drought mitigation by rhizobacteria consortium in wheat field trials

Abstract

To evaluate the drought mitigation on the yield and morpho-physiological traits of wheat by plant growth-promoting bacteria (PGPB), a two-year factorial split-plot field experiment was conducted based on a randomized complete block design. The factors were three levels of normal, moderate, and severe stress, and two levels of control and inoculated bacteria (Azotobacter, Azospirillum, Microbacterium, and Pseudomonas). The results indicated that drought stress negatively affected the morpho-physiological traits of wheat. An increase in oxidative stress and lipid peroxidation reduced wheat chlorophyll content and grain yield (GY) by 18% and 49%, respectively. Moreover, wheat root system traits, including root biomass, volume, surface area, and length density decreased significantly under drought stress. The inoculation of PGPB significantly increased the biomass, volume, and surface area of wheat roots by 48%, 31%, and 18.5%, respectively. An improved root system in the inoculated treatment with an increase in the relative leaf water content and a decrease in oxidative stress could increase leaf chlorophyll content. The PGPB inoculation significantly elevated wheat GY under normal and stress conditions, with the highest yield increase at the moderate stress level (12%). At the high stress level, however, bacterial inoculation did not significantly influence wheat yield. Altogether, the inoculation of bacteria with various growth-stimulating traits improved the morphological, physiological, and metabolic traits of wheat under drought stress, ultimately increasing wheat GY in real field conditions.