Correlation, regression and path analysis for seed yield and related traits in breeding lines derived from KO37× SE65 cross in linseed

Oilseed crops have an effective role in nutrition and industry. Flax (Linum usitatissimum) seeds contain approximately 30 to 40 percent of oil rich in unsaturated fatty acids, especially linolenic acid. Previous studies in flax had showed significant positive correlation of seed yield with number of branches per plant, number of capsules per plant and 100 seed weight. It had reported that the number of capsules per plant is the most important selection criteria for genetic improvement of seed yield in flax. The present study was conducted to investigate relationship between seed yield and its related traits in breeding lines derived from KO37× SE65 cross using correlation, regression and path analysis to determine the best indirect selection criteria for genetic improvement of seed yield in flax.

In order to study the relationships between traits, 112 breeding lines along with six genotypes as control (including parental genotypes) were evaluated in augmented experiment design. Genotypes were planted in a randomized complete block design with 3 replications. Morphological, phonological and agronomic traits such as number of days to 50% flowering, end of flowering, period of flowering, number of branches per plant, number of capsule per plant, biological yield, and seed yield per plant were measured and analyzed using SAS software(Version, 9.1).

Number of capsule per plant, number of branches per plant, seed weight per capsule and biological yield per plant were positively correlated with seed yield per plant. Based on the results of stepwise regression analysis, number of capsule per plant could enter to the model in the first step and accounted 78% of the total variation. Seed weight per capsule and the number of branches per plant were entered in the subsequent steps and could explain the 86.87% of total variation. Path analysis results indicated that number of capsule per plant had the most direct effect on seed yield per plant, whereas, number of branches per plant had the most indirect effect through number of capsule per plant. Number of capsule per plant was recognized as the most important component explaining seed yield variation in the studied population. Four factors explained the most of variation of studied traits and could explain more than 68% of the total variation.

According to the results, number of capsule per plant had the most impact on seed yield variation and also there was no significant negative correlation between this trait and other seed yield components. Therefore, number of capsule per plant can be used as an indirect selection criteria for genetic improvement of seed yield in flax.