Physiological and Biochemical Parameters as An Index for Herbicides Damage in Wheat Plants

In order to evaluate physiological and biochemical changes of wheat plants (Triticum aestivum L.) under the stress of four herbicides namely, (pinoxaden, tribenuron-methy, pyroxsulam and clodinafop-propargyl) at recommended dose on three wheat cultivars (Saka 95, Giza 171 and Shandweel 1). In a totally randomized method, an experiment was performed in El-Sharkia Governorate, Egypt. During 2020 season. The analysis of variance showed that the content of the main pigments of leaf (chlorophyll a, chlorophyll b and caroteniod), activity of catalase, peroxidase, oxidase enzymes and ascorbic acids. Data showed that   the herbicide pinoxaden was the highest toxicity while tribenuron-methy was the lowest one on the three cultivars of wheat in chlorophyll content. Chlorophyll a, the reduction percentages were17 .2, 16.8 and 13.6 %   in Giza 171, Shandweel 1 and Saka 95, respectively compared with control. The reduction percentages in chlorophyll b were 14.8, 14.2 and 11.0 % in Saka 95, Giza 171 and Shandweel 1 , respectively compared with control. The opposite picture in carotenoid the reductions were 18.8, 15.3, and 9.7 % in Giza171, Saka 95 and Shandweel 1 compared with control. On the other hand, the four herbicides led to a significant decrease in the activity of wheat antioxidant enzymes compared with control. Results showed that the oxidase and peroxidase enzymes were high sensitivity to all treatments compared with control, but ascorbic acid and catalase enzymes appear low sensitivity on all cultivars of wheat. These results showed that all used herbicides reduce plant tolerance from damage and enzymes activities, therefore it can be used as an index in physiological research.