Interactive effect of rhizobacteria and drought stress on physiological attributes of mustard

Drought stress is a major abiotic stress in mustard and its effects can be negated by the application of soil microbes. Screening of rhizobacteria for their drought stress alleviation led to the selection of two isolates namely NAD-7 and MKS-6. The experiment was conducted at ICAR-IARI during 2019-20. Plants inoculated with these microbes exhibited superior performance in terms of biomass and yield. The selected isolates were further evaluated for their effect on physiological and biochemical attributes during vegetative and reproductive stages. The stress was imposed during 35 (vegetative) and 50 DAS (reproductive) for 15 days duration and left for recovery. The drought stress exhibited significant reduction in RWC (23%), MSI (16%) and total chlorophyll content (27%) as compared to irrigated plant during vegetative stage. Similar trend was observed during reproductive stage too. Inoculation with isolates NAD-7 and MKS-6 attenuated the harmful effects of stress as shown by the improved RWC (78%), MSI (7%) and total chlorophyll (28-32,%, respectively) in contrast to uninoculated plants. Results showed that imposed stress significantly affected the parameters during both stages, but rhizobacterial inoculations attenuated the harmful effects of stress. Similar improvements were also recorded during recovery for both stages. These findings show that isolates NAD-7 and MKS-6 can improve plant physiological attributes and help plant overcome the deleterious effects of water deficit stress.