This field experiment investigated the Flami sunflower crop’s physiological response to spraying of 0, 50, and 100 µmol methyl jasmonate (MeJA) concentrations at the 6-10 leaves and pre-flowering stages and the impact of 5, 9, and 13-day irrigation intervals. The experiment was conducted in a randomized complete block design (RCBD) with a split–split plot arrangement with three replicates. The 5-day irrigation interval achieved the best values for the studied growth and physiological indicators, followed by 6 and 13 days, respectively. The MeJA spray treatment enhanced plant growth, with the highest concentration achieving the best values, producing increases in LA by 8.01%, DW by 21.69%, CGR by 14.92%, RGR by 10.65%, NAR by 18.34%, Ch. a by 22.02%, Ch. b by 24.17%, RWC by 8.65%, and proline by 17.34%, while decreasing solute leakage by 47.93% compared to control. Overall, the best interaction for growth and physiological performance of the crop was obtained for the 5-day irrigation interval and 100 µmol MeJA spray combination at the pre-flowering stage
Salih et al. (Tue,) studied this question.