Zinc oxide nanoparticles and PGPR strengthen salinity tolerance and productivity of wheat irrigated with saline water in sodic-saline soil

Abstract

Abstract Background and aims Wheat growth and productivity need an exceptional approach to resist the deleterious effects of salt stress. Methods This study proposed to assess the effectiveness of the exogenous application of plant growth-promoting rhizobacteria (PGPR; i.e., Azospirillum lipoferum SP2, Bacillus coagulans NCAIM B.01123, Bacillus circulance NCAIM B.02324, and Bacillus subtilis MF497446) at a rate of 950 g ha−1 and foliar application of zinc oxide nanoparticles (ZnO-NPs; 500 mg L−1) against irrigation with saline (from a groundwater well) and fresh water (from the Nile River water) of wheat (Triticum aestivum L.) in sodic-saline soil during 2021 and 2022 growing seasons under open field conditions. Results The integrated application of PGPR and ZnO-NPs protected wheat plants against irrigation with saline water through increasing antioxidant enzyme activities, i.e., catalase (47%), peroxidase (102%), and superoxide dismutase (106%), and K+ uptake (27%) over control. Conversely, higher stress mitigation through the integrated application was illustrated by a considerable decline in electrolyte leakage (−62%), proline (−39%), MDA (−56%), and H2O2 levels (−60%). The N uptake by wheat grains increased by 57% upon treating plants with PGPR+ZnO-NPs, which also increased the Zn contents in grain and straw by 117% and 72%, respectively. Also, PGPR+ZnO-NPs increased the activity of soil urease and dehydrogenase by 80% and 232%, respectively, in plots irrigated with saline water. Conclusion The results of the present investigation suggest the use of the integrated application of PGPR and ZnO-NPs to protect wheat plants against salinity of soil and/ or irrigation water.