WUE, protein and grain yield of wheat under the interaction of biological and chemical fertilizers and different moisture regimes

The present study aimed to investigate water use efficiency (WUE), protein and grain yield of wheat under the interaction of biological and chemical fertilizers in different moisture regimes. To that end, a split-plot based on a randomized complete block design with four replications was conducted over two cropping years of 2017–2018 and 2018–2019 at Zakah–Zabol Agricultural and Natural Resources Research Station in Iran. Irrigation regime was applied at three levels, serving as the main plot. On the other hand, biofertilizer resources along with chemical fertilizer were employed at seven levels as the sub-plots. Based on slicing of interactions, biofertilizers significantly affected offsetting the losses resulting from the moisture regime stress. Consequently, grain yield, harvest index and protein percentage in the Azotobacter biofertilizer treated with 50% of the locally common chemical fertilizer (respectively) showed a 37.8, 30.55 and 29.62% increase in comparison with the control group. The highest percent of seed protein and biological yield were observed in the treatments with a combination of Azotobacter and phosphobacteria biofertilizers, showing 61.28% and 16.13% increase, relative to the control, respectively. Azotobacter and phosphobacteria biofertilizers, alone or in combination, increased the grain yield, biological yield, harvest index, water use efficiency and protein percentage in the Arg wheat cultivar. Overall, the results of this study revealed that biological fertilizers, in addition to offsetting the losses resulting from the moisture regime stress, had a positive effect on improving the quantitative and qualitative yield of wheat.