Effect of Plant Growth Promoting Rhizobacteria (PGPR) in Yield and Yield Components of Corn Hybrid (540) under Water Stress Condition

Maize is the most important grain crop that has great economic importance and is grown worldwide. The largest areas under maize in Iran are in the regions with semidry and dry climates. Bio-fertilizers differ from chemical and organic fertilizers in the sense that they are cultures of special bacteria which do not directly supply any nutrients to crops. The phenomena of fixation and precipitation of P in soil caused a low efficiency of soluble P fertilizers such as superphosphate. The studies on the application of biofertilizers as replacements or supplements to mineral nutrients in the crop production show economic and ecological justification of their broad practical application and commercialisation of biofertilizers. Given the importance of water and fertilizer in agriculture, research leading to improvements in water efficiency and the use of chemical fertilizers is essential.
Material and In order to investigate the effect of growth promoting bacteria and different levels of phosphorus chemical fertilizer on grain yield and yield components of corn hybrid (540) under humidity different regimes, an experiment was conducted as Line source based on a randomized complete block design with three replications in Agricultural Education Center of Shahid Naseri in Karaj during 2012 and 2013. Line source was applied to four levels of irrigation (not stress, mild stress, moderate stress, severe stress). Phosphorus factor was in five levels including the application of 100% triple super phosphate fertilizer and without biofertilizer, 75% recommended chemical fertilizers with biofertilizer, 50% recommended chemical fertilizers with biofertilizer, 25% recommended chemical fertilizers with biofertilizer, biofertilizer and without chemical fertilizers, too.
The results of the experiment showed the significant effect of fertilizer treatments on all traits both in the first and second years. In comparison, the effect of different levels of phosphorus fertilizers was investigated by the application of 100% phosphorus fertilizer and without inoculation it had the highest grain yield under non-stress conditions, while with increasing of stress intensity, grain yield in 75% recommended chemical fertilizers with biofertilizer treatment under mild stress, moderate stress and severe stress conditions was 2.1%, 5.5% and 35.8 % higher than the same treatment in similar circumstances, respectively.
The result of the experiment showed that the use of plant growth promoting bacteria with a good percentage of the phosphorus chemical fertilizer, while increasing the efficiency of chemical fertilizers and soil conservation, improved grain yield under water stress conditions. The positive effect of bio-fertilizer may also be due to optimum soil pH which facilities maximum utilization of applied micronutrients to crops. Also, use of Biosuper biofertilizer had positive effects on all traits.