Effect of Plant Growth Promoting Rhizobia on Improving the Nutritional Status of Canola (Brassica napus L.) Under Salinity Stress

In order to evaluate the effect of Rhizobia inoculation on nitrogen، phosphorus، potassium، iron، zinc، manganese and copper uptake in canola under salt stress، an experiment as factorial randomized complete block design with three replications، with two factors: 1- salinity in four levels of S0، S1، S2 & S3 (0، 3، 6 &9 dS/m respectively) and 2- rhizobia isolates (in seven levels T1: control، T2: salt tolerance & dissolved insoluble inorganic phosphates، T3: salt tolerance، dissolved insoluble inorganic phosphates & produced ACC-deaminase، T4: salt tolerance، able to produce IAA & high ACC-deaminase، T5: salt tolerance، able to produce IAA، ACC-deaminase & dissolved insoluble inorganic phosphates، T6: only salt tolerance، T7: only salt sensitive) was conducted. In general، concentrations of nutrients were decreased with the increase in salinity. Results showed that inoculation had a significant effect on nutrient uptake (P<0. 01). Under the salinity stress، the highest concentrations of nitrogen (22-33 %higher than control) & zinc (20-47%) were obtained in the treatment T4. Furthermore، the highest phosphorus concentration with 11 to 37 percent higher than control was observed in the treatment T3. Also، the inoculation with the treatment T5 in S3 salinity levels، resulted in 83 & 25 percent increase in iron and copper concentrations as compared to the control، respectively. Finally، it could be stated that using of growth promoting rhizobia inoculants as a biological fertilizer was important to achieve sustainable agriculture and could be considered as a simple and economical way to improve nutrition of canola under salinity stress.