Evaluation of Path Analysis for Yield and Yield Components in Rice (Oryza Sativa L.) Under Normal and Drought Stress Conditions

In order to determine the relations between different characteristics with grain yield of rice lines, an experiment carried out with 150 F8 recombinant inbred lines derived from a cross between two Iranian rice varieties Sepidroud (drought susceptible variety, male parent) and Gharib (drought tolerant variety, female parent) along with 6 varieties as check varieties based on Augment design using Randomized Complete Block Design (RCBD) with 4 replications in two environments (stress and non–stress conditions) in the research farm of Faculty of Agriculture, University of Guilan in 2013-14 growing season. Results of variance Analysis showed that there were significant differences among lines for all studied traits. Stepwise regression for grain yield as dependent variable and other traits as independent variables showed that canopy temperature, number of panicle per plant, flag leaf length, chlorophyl b, number of filled grain per panicle, SPAD number, days to 50% flowering, proline content and panicle length (R2 = 60%) under non–stress conditions and proline content, canopy temperature and number of filled grain per panicle (R2 = 56%) under stress conditions were able to explain more effective portion of the variance. In the path analysis for grain yield the maximum positive direct effects were related to flag leaf length, number of panicle per plant and number of filled grain per panicle under non-stress conditions and number of filled grain per panicle and proline content under stress conditions that showed important characteristics in relation to grain yield.