Reduction of drought stress effects on yield and yield components of grain corn (Zea mays L.) using mixed biofertilizers and phosphorus

To study the seprate and combined effects of phosphorus fertilizer, Phosphate-solubilizing bacteria and mycorrhizal fungus on reducing drought stress damages of grain corn (SC704) during its vegetative stages under field conditions, an experiment was conducted as split plot based on RCBD with three replications at College of Abouraihan, University of Tehran in 2009. Experimental factors were drought stress as main-plot (irrigation after 50 as control, 100 and 150 mm evaporation from pan class A) and fertilizer plus biofertilizer compounds as sub-plots. Drought stress began after seedling stage. Analysis of variance showed that drought stress significantly affected most of investigated traits such as number of row/ ear, number of kernel/ row, ear weight, 1000kernel weight and grain yield. All the measured traits in compounds phosphate-solubilizing bacteria, mycorrhiza fungies and triple super phosphate treatment were higher than other treatments under water deficit stress conditions. Frthermore, grain yield in triple super phosphate treat under severe water deficit stress conditions (1.81 ton/ha) were significantly less than normal irrigation (8.38 ton/ha) and low stress conditions (4.98 ton/ha). According to this experiment, seed inoculation with phosphate-solubilizing bacteria, mycorrhiza fungies and triple super phosphate compounds affected grain yield and harvest index significantly. This experiment showed that phosphate-solubilizing microorganisms can positively interact in promoting plant growth as well as in P uptake in maize plant, leading to improve plant tolerance under water deficit stress conditions.