Paper Title
Impact of Exogenous Ascorbate on Growth and Physiology of Peanut Seedlings Treated by Norflurazon

Abstract - Norflurazon is an herbici de which inhibits the phytoene desaturase implicated in the carotenoids biosynthesis. Norflurazon 100 μM alone or in combination with ascorbate (50 mM) was applied in pre-emergence to peanut seedlings (Arachis hypogaea L.). Norflurazon treatment allowed to photobleached plants which were noticeably smaller than the control. Norflurazon impaired the photosynthetic activity by decreasing photosynthetic pigments (carotenoids and chlorophylls). The determination of malondialdehyde (MDA) a marker of lipid peroxidation showed that its contents was higher in treated plants in relation with enhanced of reactive molecules species by the herbicide and decreased of endogenous α-tocopherol. The addition of exogenous ascorbate, minimize the damage done by the herbicide on the growth (shoot length, leaf area), at the membrane (malondialdehyde content) and increase the pigments content. Furthermore, the norflurazon decreased the glutathione S-transferase activity in the leaves of seedlings of peanut, while it increased the level of reduced glutathione. This activity decreased even more with the application of exogenous ascorbate in combination with the herbicide. The herbicide alone or in association with the antioxidant increased ascorbic acid content. The supplementation of ascorbate partially alleviate the toxicity of norflurazon. Index terms - Arachis hypogaea, Ascorbate, Carotenoids Glutathione S-transferase, Norflurazon, Oxidative stress, Peroxidation.