PATH COEFFICIENT ANALYSIS FOR THE YIELD-RELATED TRAITS OF RICE LINES IN NORTH IRAN

A field experiment was performed to determine relations between yield and yieldrelated traits of rice in Mazandaran province, located in the North of Iran. For this purpose, seven breeding lines and Shirodi local cultivar were tested in randomized complete block design with three replications. Statistical analysis, including correlation coefficients, stepwise regression and path coefficient analysis was performed. The results of correlation among measured traits showed that grain yield was significantly correlated with the number of filled grains per panicle (r = 0.43), the number of unfilled grains per panicle (r = -0.40), the number of fertile tillers (r = 0.44), panicle length (r = -0.48) and fertility percentage (r = 0.52). Stepwise regression for grain yield as dependent variable (Y) and other traits as independent variables (X) showed that panicle length, the number of fertile tiller and the number of filled grains per panicle were able to explain a large portion of the variance (R^sup 2^= 0.68). Moreover, path analysis revealed that the number of fertile tiller had the highest direct positive effect on grain yield (P=0.65). The second trait was the number of filled grains per panicle (P=0.47). According to results of this study, it is evident that traits including the number of filled grains per panicle, the number of fertile tillers and panicle length can be used as criteria for improvement of rice grain yield.