Investigation of soybean cultivars response to the use of bacteria and different nitrogen levels in North Khouzestan conditions.

In orther to study the effects of different levels nitrogen and application bacteria on yield of soybean cultivars an experiment was conducted at Agricultural Research Center of Safiabad in 2007. The design was a split split plot in a completely randomized block basis with 3 replications. Main plots were consisted of 2 levels of bacteria (non bacteria and using bacteria), sub plots of 4 levels of nitrogen (0, 40, 80 and 120 kgN/ha) and sub sub plots were 3 cultivars (504, L14 and DPX). Results shows that application bacteria didn't have significant affect on grain yield, biological yield, harvest index and height of plant. This results are showed that lack activity of bacteria. A significant difference was observed among different levels of nitrogen, and application nitrogen lead to increase the number pod in plant and grain yield. This result indicated that the highest (3822.22 kg/ha) and the lowest (1950.08 kg/ha) grain yield was achieved in 0 and 120 kgN/ha respectively. The mean comparison of nitrogen levels showed that three levels of nitrogen (40, 80 and 120 kg/ha) including 0, 80 and 120 kg/ha were in the same group. On the other hand increasing in use of nitrogen from 40 to 120 kg/ha lead to increase in biological yield. Among the cultivars, the highest (3370.2 kg/ha) grain yield belonged to DPX and The lowest (3055.96 kg/ha) grain yield belonged to L14. The interaction effect between different levels of nitrogen and cultivars showed that the highest of grain yield (4308.33 kg/ha) belonged to DPX cultivar with application of 260 kgN/ha and the lowest of grain yield (1606.04 kg/ha) belonged to L14 with non of nitrogen. By considering of different response of cultivar to different levels of nitrogen and by considering to sensitivity of 504 to lodging, we can consider to use 40-80 kgN/ha, but for limited growth cultivar (DPX and L14) could be recommended.