Yield, Yield Components, Correlation Coefficients and Path Analysis of Cotton Cultivars under Drought Stress

Determining environment – associated alterations in grain yield is important in yield assessment under drought stress. Therefore this study was carried out to determine the correlation coefficients and direct and indirect effects of effective components on yield in four drought - tolerant and susceptible cotton cultivars. Cotton cultivars were considered as sub plots and 3 levels of irrigation regime [33% (I33%), 66% (I66%) and 100% (I100% of water requirement)], designated as main plots in a split plot based on complete block design with three replications at Agricultural Research Station of Kashmar, Razavi Khorasan of Iran in 2011. The results showed that all yield components, except boll weight, were negatively and significantly affected by drought stress. The results also showed that retention of greater boll numbers per plant was the main component of cultivars difference in terms of cotton seed yield. High and significant correlations were observed between yield and boll number per plant, biological yield and harvest index under drought stress. While there was only significant correlations between seed yield with plant height and biological yield under non-stress condition. Path analysis showed that the most important component of cotton seed yield is biological yield under both drought stress and non-stress conditions and other components such as: boll number and weight, earliness percent and harvest index caused an increase in cotton seed yield by indirect effect on this component.