Influence of Phosphate Solubilizing Bacteria on the Growth of mustard Grown Under Drought Stress Conditions

In the present study, the influence of phosphate solubilizing bacteria (PSB - Bacillus subtilis and Bacillus velezensis) was investigated on the growth of mustard varieties (Rainbow and Punjabi Sarson) under drought stress. Fresh cultures (24 h old) of PSB isolates were used to soak the seeds for 2–3 h prior to sowing. The PSB inoculum was also applied as foliar spray at three leaf stage. Drought stress was given to mustard plants at three different stages i.e., Leaf stage, Flowering Stage and Pod Formation Stage. Drought duration remained for 14 to 21 days. PSB inoculation significantly enhanced the growth parameters such as plant height (65%), root and shoot length (60%), number of leaves and branches (50%), number of pods per plant (67%) grains number (62%) and weight (63%) over the stressed control plants. The drought-stressed mustard plants treated with PSB showed significant increase in the relative water content (28.1%), and decrease in electrical conductivity (30.2%). Antioxidant analysis showed a significant increase in total phenolic content (40%), total flavonoids (45%), and superoxide dismutase (10.51%) in PSB treated plants under drought stress. Moreover, an increase in nutrient analysis of nitrogen (11.4%), potassium (14.5%) and phosphorus (19.9%), was recorded in PSB-inoculated plants under drought stress. In conclusion, the PSB isolates enhanced the growth of mustard plants under drought stress. Integrative use of effective PSB appears to be an effective eco-friendly approach to increase drought tolerance in mustard varieties grown under drought stress conditions.