Efficiency of phytoprotectants and phosphorus solubilizing bacteria in modulating of water deficit effects on wheat

Field studies were carried out for two years at the research farm of the Faculty of ‎Agriculture‏ ‏and Natural Resources, University of Mohaghegh Ardabili. Experiment was conducted as a split plot ‎factorial based on randomized complete block design with three replications. The main factor included drought ‎stress at three levels [irrigation at 80% of field capacity (no stress), irrigation at 65% of field capacity (moderate ‎stress) and irrigation at 50% of field capacity (severe stress)]. Sub factor was combination of external ‎phytoprotectants application at five levels [Distilled water as control, Ascorbic acid (1 mM), Tocopherol (1 mM) ‎‎, Silicon (1 mM) and Zinc NPS (1 mM) and inoculation with phosphorus-solubilizing bacteria at two levels (with ‎and without inoculation)]. ‎The severe water limitation (50% field capacity) compared to non-stress conditions (irrigation at 80% ‎field capacity), led to a significant decrease in wheat yield and yield components. However, the application of ‎organic (ascorbic acid and tocopherol) and mineral (silicon and zinc NPS) phytoprotectants, as well as ‎inoculation with phosphorus-solubilizing bacteria were significant on Chl a, Chl b content and also, leaf area ‎index and increment of the effective compounds in plant tolerance under stress conditions such as carotenoieds, ‎prolin and slouble sugars. under the severe water limitation, ‎application of stress modulators increased grain yield 28, 18.2, 17.3 and 9.3% in compared to no application of ‎stress modulators at the same level of irrigation‎