Effect of Biofertilizer and Nano-Fe Oxide Foliar Application on Alleviation of Water Deficit in Yield and Some Physico-Chemical Properties of Barley

The use of biological systems and nano-micronutrients are gaining increased attention since they are more ecofriendly on plant growth under water stress. The aim of this study was to investigate the response of yield, physiological, and chemical characteristics of barley (Hordeum vulgare L.) to water deficit, biofertilizers and iron Nano-oxide in the field condition. Treatments were included biofertilizers [application of plant-growth-promoting rhizobacteria (PGPR), arbuscular mycorrhizae fungi (AMF), PGPR + AM-fungi and not application as control]; nutrition with nano-iron oxide (control, application of 0.3, 0.6 and 0.9 g/L) and irrigation levels [normal irrigation, moderate and severe water limitation]. The results showed that water limitation caused a decrease in SPAD (Soil Plant Analysis Development), F_v/F_m, relative water content, and grain yield of barley, whereas electrical conductivity, proline, soluble sugars, and enzyme activities increased. Combined interactions between 0.9 g/L nano-Fe oxide with AM-fungi + PGPR ameliorated adverse effects by enhancing RWC and proline, which might result from of lower electrical conductivity. The highest proline was detected in plants exposed to the highest nano-Fe oxide and mycorrhiza + Azospirillum application, at all irrigation levels. Catalase, peroxidase, and polyphenol oxidase activities increased by 44.7, 105.3, and 107.5% in plants treated with mycorrhiza and PGPR under severe water limitation. Iron deficiency induced several changes in catalase and peroxidase enzymes and reduced their activities under water deficit. In severe water-stressed plants, the application of AM-fungi and PGPR caused an increase in grain yield by 10.35%. Spraying of 0.9 g/L nano-Fe oxide and application of mycorrhiza + Azospirillum could be suitable for barley growth and production in semi-arid areas.