Evaluation of Oxidative Stress Indices in Two Rice (Oryza sativa L.) Varieties Subjected to Post-emergence Application of Bensulfuron-methyl and Bispyribac-sodium Herbicides at Different Times

This study focused on evaluating indices of oxidative stress in Faro 51 and Faro 59 rice varieties subjected to bensulfuron-methyl and bispyribac-sodium herbicide treatments at different application times. Using a split-plot experimental design replicated three times, a field study was carried out during the 2024 rainy season at the Research Farm of Adamawa State University, Mubi. The study treatments consisted of: two rice varieties, three periods of herbicide application, bensulfuron-methyl and bispyribac-sodium herbicides each at 200 and 400 g/ha and 200 and 400 ml/ha concentrations respectively and hoe weeded and weedy check were used as controls. The leaf samples of the rice plants from each treatment plot were obtained at the first and third Weeks after Treatment (WAT). The results showed that weedy check treatment resulted to lowest production of superoxide dismutase and catalase at the first and second sampling than the hoe weeded and herbicide treatments. The malondialdehydes (MD) rate due to hoe weeded (6.08 µmol/g) and 200 g/ha bispyribac-sodium (4.50 µmol/g) treatments were the lowest at first and second sampling respectively when compared with that of other treatments. Also, the 2, 3 and 4 Weeks after Sowing (WAS) application times had significant difference in their effect against the rate of antioxidants production in the rice plants. The 2 WAS caused the highest rate of MD, ascorbic acid (AA) and hydrogen peroxide (HP) than 3 and 4 WAS application times. The highest rate of superoxide dismutase (SD) and catalase at the first and second sampling were on the other hand recorded at 4 WAS application time. Again, the herbicide effect based on the rice variety showed that, Faro 51 & Faro 59 rice varieties had significant difference in their rate of antioxidants production. Faro 51 had the highest rate of MD, AA and HP than Faro 59. However, Faro 59 had the highest of SD and catalase than Faro 51. The study concluded that, Faro 59 rice variety has more resistance to oxidative stress than Faro 51 rice variety when subjected to bensulfuron-methyl and bispyribac-sodium herbicides. The application of the two herbicides at 2 WAS induce more oxidative stress on the two rice varieties than at 3 and 4 WAS.