Effects of zeolite, vermiculite, and superabsorbent application on agronomic and physiological traits of safflower in response to water-deficit stress

Drought is the most important stress factor that reduces plant growth and yield. However, the application of moisture absorbents may decrease the negative effects of drought. This study aims to investigate the effect of irrigation levels (irrigation after 140, 100, and 70 mm evaporation from pan evaporation) and moisture absorbents (without moisture absorbent, superabsorbent, vermiculite, zeolite, and the combined use of all three moisture absorbents) on yield components and physiological characteristics of safflower (Carthamus tinctorius L. cv. Goldasht). This experiment was performed in 1397 and 1398 as the split-plot design using the randomized complete block design with three replications. Results showed that under 140 mm evaporation due to the severe drought, seed yield and oil yield declined by 36.3% and 46.6%, respectively, as compared to the 70 mm evaporation. As usual, drought increased the malondialdehyde content significantly. Water absorbent treatments increased the grain yield as compared to the control. However, there were no significant differences in the effect of water absorbents on the grain yield but the most effective moisture absorbent to increase the oil yield was zeolite. Oleic and palmitic acids percent increased due to drought, while the amount of linoleic acid decreased with increasing the irrigation intervals. In conclusion, the results showed that the use of moisture absorbents alleviated the adverse effects of drought stress on the safflower yield and some yield components.