Effect of water limitation and application of bio-fertilizer and nano-silicon on yield and some biochemical traits of wheat

To study the effect of water limitation and application of bio-fertilizer and nanosilicon on yield and some biochemical characteristics of wheat, a factorial experiment was carried out in a randomized complete block design with three replications in the research field of Faculty of Agriculture and Natural Resources, University of Mohaghegh Ardabili, Ardabil, Iran, in 2018-2019. Experimental factors were included irrigation in three levels (full irrigation as control and irrigation cut-off at 50% of booting and heading stages, based on codes 55 and 43 of the BBCH scale, as moderate and severe water limitation, respectively,), foliar application of nano-silicon (water spraying as control, 30 mg/L or 22.5 mg/m2  and 60 mg/L or 45 mg/m2 nano-silicon) and bio-fertilizer (no application as control, application of mycorrhiza (Glomus mosseae), application of flavobacterium + pseudomonas strain 186, combined application of mycorrhiza and flavobacterium + pseudomonas). The results showed that the highest antioxidant enzymes activity and soluble sugars were obtained by combined application of bio-fertilizers and foliar application of 30 mg/L nano-silicon under the condition of irrigation limitation at booting stage. Under full irrigation condition and non-application of bio-fertilizers and nano-silicon, the activity of catalase, peroxidase and polyphenol oxidase enzymes and soluble sugar content decreased 78, 49, 64 and 74 percent, respectively, compared to severe water limitation at booting stage and combined application of bio-fertilizers and 30 mg/L nano-silicon. Maximum proline content was also obtained by foliar application of 60 mg/L nano-silicon (9.50 µg/g FW) and combined application of bio-fertilizers (9.70 µg/g FW) under severe stress conditions (10.97 µg g Fw-1). Hydrogen peroxide (H2O2) content under severe water limitation at booting stage and non-application of bio-fertilizers and nano-silicon was 90% higher than the application of 60 mg/L nano-silicon and combined application of bio-fertilizers under full irrigation condition. The highest grain yield (4593 kg/ha) was obtained from the foliar application of 30 mg/L nano-silicon and combined application of bio-fertilizers under full irrigation conditions. The results of current study showed that the combined application of bio-fertilizers and nano-silicon can increase wheat grain yield under water limitation conditions by improving plant biochemical characteristics.