Study of soybean genotypes reaction to the application of bacteria and different nitrogen levels in North Khouzestan conditions

In order to study the effect of different levels of nitrogen and bacteria application on the yield of soybean genotypes, an experiment was conducted at Safiabad Agricultural Research Center in 2007. The experiment was implemented as a split split plot completely randomized block with 3 replications. Main plots consisted of 2 levels of bacteria (use and non-use of bacteria), while sub plots included 4 levels of nitrogen (0, 40, 80 and 120 kgN/ha) and sub-sub plots were 3 genotypes (504, L14 and DPX). Results showed that application of bacteria did not have a significant effect on grain yield, biological yield, harvest index, plant height and number of nodesper plant. These results showed the lack of nitrogen fixation bacterial activity in climatic North Khouzestan cinditions.The application of nitrogen led to increasing the number of pods per plant and grain yield. This result indicated that the highest (3822.22 kg/ha) and the lowest (1950.08 kg/ha) grain yield belong to 0 and 120 kgN/ha, respectively. Nitrogen × genotypes interaction effect showed the highest grain yield (4308.33 kg/ha) belonged to DPX genotype with the application of 120 kgN/ha and the lowest grain yield (1890 kg/ha) belonged to L14 without the application of nitrogen. Considering the different genotypes’responses to different levels of nitrogen and the sensitivity of indeterminate genotype (504) to lodging, it is suitable to use 80 kgN/ha for 504 and L14 genotypes, but for determinate growth genotypes (DPX) the use of 120 kgN/ha can also be appropriate.