Effect of Water Stress on Physiological and Biochemical Traits of Safflower Genotypes

Water stress affects the crucial processes and yield of crops. This study aimed to investigate the effect of water stress on physiological and biochemical traits of safflower genotypes.

A factorial experiment was carried out as randomized complete block design in Seed and Plant Improvement Research Institute during 2017-19. The treatments included two irrigation levels (40 and 80% depletion of available water) and Parnian, Goldasht and Kazak genotypes. Plants were sown in soil columns with a height of 150 and a diameter of 23 cm, and irrigated by a drip system. Antioxidant enzymes, malondialdehyde, proline, relative water content, chlorophyll, seed yield and fatty acid composition were measured at the end.

Water stress significantly increased the accumulation of hydrogen peroxide and malondialdehyde in safflower genotypes which led to increased catalase and peroxidase enzyme activity by 1 and 2.5 U, respectively. The proline content increased about 16 times under water stress conditions. In contrast, the relative water content showed a significant decrease, which resulted in increased canopy temperature and decreased seed yield by 70%. The Kazak genotype had the lowest increase in canopy temperature under stress conditions and showed higher yield stability. Moreover, the fatty acid composition of seed oil changed and the amount of linoleic acid decreased by 1.8% under water stress conditions.

The results showed that in addition to drought-related physiological traits, no increase in saturated/unsaturated fatty acid ratio is also an important indicator in screening superior genotypes for cultivation in water shortage.