Study the relationships between grain yield and some morpho-physiological traits of safflower under normal and low water stress conditions

To study the relationships between grain yield and other morpho-physiological traits of ten genotypes of safflower under normal and water stress conditions, a split plot experiment was conducted in a completely randomized block design with three replications. The main factor included irrigation regime in two levels (full irrigation and water stress in the flowering stage) and the sub-factor in ten levels included 10 safflower genotypes. In both full irrigation and low water stress conditions, the highest positive and significant correlation was observed between grain yield and seed number per plant. Based on stepwise regression results, in complete irrigation conditions, harvest index, dry weight, day to flowering, seed diameter, number of seeds per boll and main stem diameter, and under stress conditions, dry weight, harvest index, number of sub-branches , Chlorophyll content and boll diameter explained 97.6% and 99.1% of grain yield changes, respectively. The results of path analysis showed that under full irrigation conditions, traits of relative lost water, dry weight, seed diameter and harvest index, and under water stress conditions, traits of chlorophyll, number of sub-branches, dry weight and harvest index had the most direct and significant effect on grain yield. Therefore, based on stepwise regression and path analysis, under full irrigation conditions, dry weight and harvest index, and under water stress conditions, in addition to these two traits, chlorophyll content and number of sub-branches had the greatest effect on grain yield.

Keywords:

Morpho-physiological traits , Safflower , Stepwise regression , Path analysis , Water stress