Effect of Different Isolates of Azospirillum on the Yield and Uptake of N, P and K in Canola

The bacteria of genus Azospirillum is one of the plant growth-promoting bacteria with N2 fixation ability that has been observed in the rhizosphere and the intercellular of the cereals and other plant roots. In this research the effect of some indigenous isolates was surveyed on some of the growth parameters and nutrients uptake. In this research 58 Azospirillum isolates were isolated from 38 samples of soils and canola roots from the different regions of Golestan province, Iran. Then they were compared to select the superior growth promoting isolates. The effect of inoculation of superior isolates on canola (the variety of Hayola 401) was carried out under growth chamber conditions, at fertilizer level (50% and 100%, based on soil test), in randomized complete block design (RCBD) with 3 replications and 2 harvest stages. The inoculation of 4 Azospirillum isolates on some of the growth parameters of canola showed that the bacterial treatments significantly increased shoot dry weight, potassium and nitrogen uptake compared with the control in the first harvest, but they did not have any significant effect on all parameters in the second harvest. The maximum amounts of potassium and nitrogen uptake and the maximum amount of shoot dry weight were observed in inoculated plant by auxin-producing isolate with the amounts of 34.01, 31.43, and 0.627, respectively, in the first harvest. Also the effect of fertilizer treatments was significant on amounts of plant nutrients uptake and shoot dry weight in the first harvest, and on shoot dry weight, root dry weight, plant potassium, and nitrogen uptake in the second harvest. The highest amounts of nutrients uptake, shoot dry weight, and root dry weight in the both harvest stages wereobserved in 100% fertilizer treatment.