The Effect of Hormone Spraying and Bacterial Inoculation on Pinto Bean under Different Temperature and Humidity Conditions

Pinto bean (Phaseolus vulgaris) is being sown in Iran from April to July. To investigate the effect of acetylsalicylic acid (ASA) and Bacillus velezensis bacteria on pinto bean yield and yield component, an experiment was conducted as a split-split plots experiment in a randomized complete block design with four replicates in the research farm of the college of Agriculture and Natural Resources, University of Tehran in 2021 on separate planting dates (mid May and late June). The treatments included two irrigation levels (irrigation 70% and 100% of the plant's water requirement) as the main plot, foliar spraying (ASA hormone at 0.5 mM level and control) as a secondary plot and inoculation with Bacillus velezensis bacteria and no inoculation as a secondary subplot. Results of the analysis of variance showed that the interactions of sowing date, irrigation, foliar spraying, and inoculation with bacteria on the traits measured in pinto beans was significant. The maximum plant height (154 cm), number of sub-branches (7), leaf area index (7.3), seed yield (3045 kg/ha), and harvest index (43%), 100 seed weight (37 g), pod number (24) were obtained in mid-May planting date, along with salicylic acid foliar spraying and bacterial inoculation without water stress. The highest biological yield (7997 kg/ha) was obtained under water deficit stress (70% of plant water requirement) and foliar spraying with ASA hormone and inoculation with bacteria, in late June sowing date. Overall, hormone spraying and inoculation with bacteria improved the yield characteristics of pinto bean under drought-stress conditions in both sowing dates.