Analysis of Correlation and Stepwise Regression between Grain Protein Yield and Related Traits of Maize in Conditions of Drought Stress and Zinc Sulfate Spraying

ABSTRACT:In order to study and analyze the stepwise regression and correlation between protein yield and related traits of corn under the conditions of drought stress and zinc sulfate foliar application, a split-plot experiment was carried out on maize hybrid single cross 704 in the summer of 2011-2012 cropping season as randomized complete block design with three replications. The main plot included three levels of full irrigation (control), irrigation-off at tasseling stage, irrigation-off at milky stage and the subplot included zinc sulfate foliar application at four levels of no foliar application, foliar application at 8-leaf stage, foliar application at 12-leaf stage, and foliar application at 8-and-12-leaf stage together. Results indicated that there is a positive significant correlation between grain protein yield and biological yield(r=0.82). Accordingly, biological yield increase led to the increase of protein yield in the maize. Results of stepwise regression of grain protein yield as dependent variable versus other traits as independent variables were studied. Equation of grain protein yield resulted from stepwise regression with coefficient of 99% is comprised of two components: biological yield and index harvest. Biological yield of 98.5% justified grain yield changes according to the equation Y=-679.4+78.2X1 + 0.0865 X2 which indicates the effective role of growth conditions of vegetative organs and biological yield in grain protein yield within this experiment.