Studying correlation and regression equations between traits of grain corn under different fertilizer combinations and drought stress condition

In order to study the combined and separate effects of phosphorus fertilizer, phosphate-solubilizing bacteria and mycorrhizal fungus on adjusting and reducing the loss of yield resulting from drought stress during the stage of growth of grain corn (SC704) an experiment was performed in Aboureihan Campus of the University of Tehran, Iran, during 2007-2008. The experiment was conducted as split plot based on a randomised completely block design (RCBD) with four replications. Experimental factors were drought stress as the main-plot [irrigation after 50 [without drought stress], 100 and 150 mm evaporation from pan class A, and fertilizer compounds as the sub-plot (100% phosphorus (b5), 50% super phosphate triple+ mycorrhizal fungus + Phosphate-solubilizing bacteria (b2), mycorrhizal fungus + Phosphate-solubilizing bacteria (b1), 50% super phosphate triple + Phosphate-solubilizing bacteria (b3), and 50% super phosphate triple + mycorrhizal fungus (b4)). Drought stress happened after seedling establishment. Result of variance analysis showed that drought stress significantly affected plant height, stem dry weight, stem diameter, ear height, kernel number per row, 300 kernel weight, ear weight, ear length, ear diameter, cob diameter, kernel depth, cob percentage and total yield traits. Also, there was not significantly difference between fertilizer treatment for number of Leaf per plant, stem diameter and ear height traits. All the assessed traits in b2 inoculated treatment showed of higher values than other treats under water deficit stress condition. Furthermore, the investigated traits of b5 treat under severe water deficit stress were significantly less pronounced than normal irrigation and low stressed conditions. The results showed that all measured traits in seed inoculums with b2 under the low drought stress stood higher than other treats. Using stepwise regression was performed for grain corn in all conditions and in high stress conditions four traits have been extracted, which describe most 90% of yield variations. These results have completely coincidence with simple correlation analysis.