Compensate for reduced yield due to late water stress by using growth enhancers in the tillering stage of wheat (Triticum aestivum L.)

The application of foliar spraying can be practical in critical stages for alleviating plant nutritional needs in the short term. To investigate the effect of growth enhancers in the tillering stage of wheat on the compensation of required compounds from storage sources to grain in the remobilization process in the stopping last irrigation, an experiment was carried out in a split-plot arrangement based on a randomized complete block design with three replications at the farm of Kashmar research station in 2020-2021. The main plots were two variety of wheat: V1: Sirvan and V2: Rakhshan, the subplots were growth enhancers including (T1: Control, T2: Urea phosphate (10 kg.ha-1) + solopotas (8 kg.ha-1) + amino acid (2:1000); T3: Urea phosphate (10 kg.ha-1) + solopotas (8 kg.ha-1) + micronutrient (2:1000); T4: Urea phosphate (10 kg.ha-1) + solopotas (8 kg.ha-1) + humic acid (2:1000). The results showed that the highest plant height was obtained from T3 treatment in the Sirvan cultivar. In both Sirvan and Rakhshan varieties, the highest peduncle length was recorded from a foliar spray of T3. The highest plant dry weight (1290 g.m-2) per square meter was also obtained from T2 in Sirvan. Grain weight per square meter in the Sirvan cultivar was 651, 582, and 462 g.m-2 from the application of T2, T3, and T4, respectively, which was higher than the Rakhshan cultivar in these treatments. The highest amount of photosynthesis was 19.1 μCO2mol.m-2. s-1, stomatal conductance, and intercellular CO2 (Ci) were obtained in the Sirvan cultivar by T2 application. In general, the effect of T2 treatment on photosynthesis and yield indicates compensation for the lack of grain yield (52% increase) and biomass (51%) due to the last water stop in the Sirvan cultivar.