EXAMINATION OF AGRO-PHYSIOLOGICAL TRAITS OF DIFFERENT CULTIVARS OF MAIZE (Zea Mays) WITH LEAF AND EAR TOPPING

The biochemical traits of different maize varieties under leaf and cob defoliation conditions were investigated in a factorial experiment, a randomized complete block design with three replications during two crop years of 2017-18 and 2018-19. Treatments consisted of removing leaves and a part of the cob at three levels of control, removing half of the cob after pollination, and removing two upper and lower leaves of the cob after pollination as the first factor. The second factor comprised seven maize varieties including SC704, Kansor, Kordona, Karaj 703, Koosha, Fajr, and Danial 690. After preparing the substrate in the first and second years, seeds of different varieties were planted in the plots based on the treatments. Leaf and cob defoliation treatments were applied after pollination. The results showed that the highest contents of chlorophyll a (98.46 mg/g fresh weight, FW), chlorophyll b (138.7 mg/g FW), carotenoids (74.33 mg/g FW), and anthocyanin (1.915 mg/g FW) were obtained in the SC704 variety under combined treatment of defoliating two upper and lower leaves of the cob. The highest amount of catalase (58.73 mg protein/min) was recorded in Fajr variety in the control, but peroxidase (173.4 mg protein/min) and polyphenol oxidase (64.7 mg protein/min) activities were uppermost in the Koosha variety of the control treatment.