Effect of water deficiency on seed quality and physiological traits of different safflower genotypes

Safflower is one of the most adapted oilseed crops to the drought-prone arid lands. This experiment was carried out to evaluate the effects of water deficiency on some physiological traits such as proline content, soluble carbohydrate content, relative water content (RWC), and seed quality using 64 safflower genotypes grown under normal and water-deficient field conditions. Plants were grown under normal irrigation until the branching growth stage, when water deficiency was applied to the plants. Results of combined analysis of variance showed the significant effects of genotype, water deficiency, and their interactions on the tested traits. RWC, seed oil content, and oil yield significantly decreased whereas proline, soluble carbohydrate, and protein content increased in response to water deficiency. Cluster analysis divided genotypes into 3 groups of sensitive, tolerant, and semitolerant genotypes under water-deficient conditions. The second group (tolerant group) possessed the lowest seed yield loss due to water stress and produced the highest seed protein content and seed oil yield under water-deficient conditions. The superior seed yield and quality was closely related to the physiological properties of the plants, resulting in higher leaf proline, carbohydrate, and RWC under water-deficient conditions. The results suggest that leaf proline content, carbohydrate content, and RWC would be useful traits to select for water stress-tolerant plants in safflower.