Evaluation the nutrient content of different rapeseed (Brassica napus L.) cultivars under the effect of Azotobacter and irrigation

In order to evaluate the yield and nutrient accumulation in different cultivars of rapeseed under the effect of azotobacter in irrigation conditions, a factorial split experiment based on randomized complete blocks design with four replications was conducted in Khorramabad agricultural research station in 2016-2017. Experimental factors included the withholding irrigation from 30% flowering and 30% pod forming, and normal irrigation (control) as the main plot and inoculation of  Neptune, Oktane and Okapi rapeseed cultivar seeds with azotobacter strains (63, 70) and non inoculation (control)as subplots. The results showed that the irrigation regimes had a significant effect on grain yield and the accumulation of nitrogen, phosphorus, potassium, calcium, magnesium, and manganese in shoot and seeds. The effect of azotobacter was significant on all nutrients (except magnesium) uptake in green tissue and seeds. The interaction effects of irrigation regime, bacteria and cultivar were significant on phosphorus, potassium, magnesium, manganese, and zinc levels in shoot and grain. Maximum grain yield was obtained from optimal irrigation treatment with 4559 kg.ha-1. It was found that Oktane and Neptune cultivars with 4584 and 4290 kg grain.ha-1were superior compared to okapi cultivar. With regards to the positive effect of potassium concentration and inoculation of rapeseed seeds with azotobacter due to its solubilizing properties, increasing the application of potassium in soil and seed inoculation can moderate the negative effects of stress and improve grain yield in rapeseed.