Correlation Coefficient, Path Analysis and Drought Tolerance Indices for Wheat under Deficit Irrigation Conditions and Nitrogen Levels

In order to investigate the indices of drought tolerance, correlation coefficient and path analysis at deficit irrigation and nitrogen experiment, this experiment was conducted as split plot arranged in a randomized complete block design (RCBD) with three replications during 2000-2003 for wheat at Maragheh agricultural research station of DARI. The treatments were included four levels of deficit irrigation (Rainfed, 100, 160 and 220mm of water use) as main plots and five nitrogen rates (0, 30, 60, 90 and 120 kg.N.ha-1) as sub plots. Grain, straw and biological yield, harvest index, productivity degree, plant height, kernel number per spike, Spike number per square meter and TKW determined from the middle of each plot. There were positive significant correlations due to grain yield with all variables: harvest index (r = 0.969 ), Productivity degree (r = 0.952 ), straw yield (r = 0.904 ), plant height (r = 0.904 ), biological yield (r = 0.824 ), Spike number per square meter (r = 0.817 ), kernel number per spike (r = 0.773 ) and TKW (r = 0.612 ) respectively. Results of path analysis showed that increase in grain yield was due to increase spike number per square meter and kernel number per spike respectively. On based of indices of drought tolerance (Tolerance Index, Mean Productivity, Geometric Mean Productivity and Harmonic Mean), treatment of %66full irrigation combined with 90KgN.ha-1 was substantially increased water productivity