The effect of plant growth promoting rhizobacteria on some physiological traits of black cumin (Nigella sativa L.) under water deficit stress

In order to evaluate the effect of plant growth promoting bacteria (PGPR) on some physiological traits of Black cumin under Water Deficit Stress, a split-plot experiment based on randomized complete block design with three replications was conducted at the research farm of Shahrekord University in 2015- 16. Factors were irrigation in three levels (100, 75 and 50 % of water requirement) and bacteria in seven levels (control, Bacillus sp. Strain A, Bacillus amyloliquefaciens, Bacillus sp. Strain B, Azotobacter chroococcum, Pseudomonas putida and Azopirillum lipoferum). Results showed a significant effect of water deficit, PGPRs and their interaction on all traits. It was demonstrated that in 50% of water requirement treatment reduced total chlorophyll, RWC and grain yield by 28%, 14.4% and 28.4%, respectively. Within each three irrigation levels, the bacterial treatments had the maximum amount of measured traits than control treatment. So that all PGPRs under 50% water requirement treatment could increase chlorophyll b, RWC and grain yield as compared to control. Also, B. amilolykofosins and strainB application under 75% water requirement treatment had the highest grain yield. Overall, this increase was more significant in B .amilolycophysin, Bacillus strain A, strainB and Azopirillum lipoferum treatments. according to the this study results, inoculation of Black cumin seeds with PGPRs is recommended to increase physiological traits and crops yield and alleviation of adverse effects of water stress.