Evaluation of direct and indirect effects of some traits in different rice genotypes under salt stress conditions using path analysis

Eighteen rice genotypes were used to determine relations among main quantitative traits and the contribution of each trait to the total dry weight production in three salt stress levels (3, 6 and 8 dS/m levels) through correlation coefficient and path analysis. The seven related traits included seedling height (x1), shoot length (x2), root length (x3), tiller number (x4), shoot dry weight (x5), root dry weight (x6) and leaf dry weight (x7) on total dry weight (y) production was recorded. The results of the ANOVA for estimated traits showed significant differences (P < 0.01) among genotypes for all traits. At 3 dS/m level, the values of the correlation coefficient with total dry weight were ordered as x6 > x5 > x7 > x2 with 0.945, 0.828, 0.823 and 0.634, respectively. The results of correlation coefficient at 6 dS/m level exhibited that root dry weight was again positively correlated with total dry weight (P < 0.01). At 8 dS/m salinity level, shoot dry weight was positively correlated with total dry weight (P < 0.01). Result based on direct and summation of indirect effects exhibited that direct effect of root dry weight was higher than indirect effect at 3 and 6 dS/m salt stress levels. But, at 8 dS/m salt stress level, shoot, root and leaf dry weight direct effects with 0.499, 0.429 and 0.329 were higher than indirect effects. Results recommended that breeders should select genotypes with higher root, shoot and leaf dry weight at salt stress conditions. Therefore, these traits seem likely to be found in rice genotypes material adapted to salt stress conditions and can be used in future breeding programs.