Effects of cycocel and micronutrients on yield, physiological traits, and antioxidant activity of maize (Zea mayz L.) in low irrigation conditions at the end of the season

In order to investigate the effect of cycocel and micronutrient consumption on yield, physiological traits, and antioxidant content of maize under low irrigation conditions at the end of the season, a split factorial experiment was carried out based on a randomized complete block design with four replications in Safiabad Agriculture Research Center in Dezful during two cropping years 2017-18 and 2018-19. The main treatment included water stress with three levels control (without water stress), water stress in female flower formation stage and water stress in grain swelling stage. Also, foliar application of cycocel at three levels of control (no use of cycocel), 442.5 ppm, and 885 ppm and three levels of micronutrient fertilizers, namely control (no fertilizer application), foliar application of 1000 g. ha-1, and foliar application of 1500 g. ha-1 were considered as the sub-factors. Results of the combined ANOVA showed that the interaction of the effects of year, stress, micronutrient, and cycocel on relative water content, proline and grain yield and also the interaction of the effects of stress, micronutrient, and cycocel on hydrogen peroxide, glutathione peroxidase, and soluble proteins were statistically significant (p≤0.01). The results also showed that the highest activity of superoxide dismutase enzyme was obtained under stress conditions at the grain swelling stage, which showed an increase by about 37% compared to the irrigation treatment under optimal conditions. Foliar application of 1500 g. ha-1 micronutrient and 885 ppm cycocel in non-stress conditions increased the average grain yield (11500 kg. ha-1) in the second year by about 85% compared to stressed condition at grain swelling stage and no application of micronutrient and cycocel. In general, to increase grain yield under optimal irrigation conditions and reduce the drop in stress conditions, growth regulators such as cycocel with a concentration of 885 ppm and micronutrient foliar application at 1500 g. ha-1 are recommended.