Plant growth promoting bacteria effects on growth, photosynthetic pigments and root nutrients uptake of Avena sativa L. under drought stress

Drought stress is one of the most important factors affecting plant growth. plant growth under drought stress may be enhanced by the application of microbial inoculation including plant growth promoting rhizobacteria. this research was conducted as a factorial experiment in a completely randomized design. the first factor included the bio-fertilizer (a. vinelandii (a)), p. agglomerans+ p. putida stroin (p), a + p and control (without bio-fertilizer). the second factor was drought stress at three levels of field capacity (fc), 0.7 fc and 0.4 fc. the results showed that treatment a + p at fc level had the highest effect on increasing photosynthetic pigments (p<0.01 ). while the lowest amount of photosynthetic pigments occurred in the treatment a at fc level. the highest and lowest shoot fresh weight was belonged to the treatments p at 0.7 fc and the treatment a at 0.4 fc, respectively (p<0.01 ). the highest and lowest root fresh weight was respectively was belonged to the control treatment at 0.7 fc and 0.4 fc, respectively (p<0.01 ). the results showed that the use of bio-fertilizers separately had more positive effects on the nutrients uptake of a . sativa l. in general, the results of this study suggest that growth promoting bacteria as biofertilizers have a greater effect on growth, photosynthesis pigments and nutrient uptake of a. sativa l. the use of these bacteria did not actually reduce the effect of drought stress on the plant.