Trait Relationships in Five Species of Carthamus under Normal and Deficit Irrigation

Littele is known about the relationships of different traits in safflower using wild and cultivated species. In this study, 46 safflower genotypes from five different species were evaluated under normal and deficit irrigation and the relationship of traits was assessed. Results showed that water stress had significant effect on head yield per plant, number of seeds per head, head diameter and 1000-seed weight but didn’t have significant effect on other traits. Positive and significant phenotypic correlations were observed among seed yield per plant with oil percent, number of heads per plant, head diameter, head yield per plant and number of seeds per head for both irrigation regimes, which were confirmed by genetic correlations. Based on stepwise regression, number of seeds per head justified the majority of seed yield variation for both stress and non-stress conditions. However, under normal conditions, the number of traits entered into the model and the justified variation was more than moisture stress conditions. Path analysis showed that number of heads per plant had the highest direct effect on seed yield in non-stress conditions and can be used to indirectly improve seed yield in safflower. Under stress conditions, number of seeds per head had the highest direct effect on seed yield. Factor analysis revealed four factors which explained more than 82 and 85 percent of variance in non-stress and stress conditions, respectively. These factors were named the sink, plant morphology, oil and economical factor in non-stress conditions. Under stress conditions, the factors were named the economical factor, plant morphology, sink and seed weight. The relationships between traits discussed in this study can be exploited in indirect selection to improve the important traits of safflower (such as seed yield and oil content) economically, through traits with higher heritability, with emphasis on wild germplasm.