Ph.D. Tezi Görüntüleme

      Effects of leaf rolling on photosynthetic machinery of maize plants under drought stress were studied. Fourteen maize cultivars were grown in a greenhouse during grain filling. Drought stress and artifical prevention of leaf rolling were applied to fourteen maize cultivars grown under greenhouse conditions. Cultivars were grouped according to their drought sensitivity and resistance. Different leaf rolling responses were determined between sensitive and tolerant cultivars. As a result of leaf rolling and severe drought stress, decreases in leaf water potential (Ψleaf), stomatal conductance (gs), oxidized glutathione (GSSG) content, maximum quantum yield of PS2 (Fv/Fm), effective quantum yield of PSII photochemistry (ΦPS2), electron transport rate (ETR), photosynthesis rate (Pn), transpiration (E) intracellular CO2 (Ci), ear weight and 100 kernel weight were determined compared to control. On the other hand, significant increases were observed in terms of lipid peroxidation, hydrogen peroxide (H2O2) and proline content, guaiacol peroxidase (GPX), ascorbate peroxidase (APX), superoxide dismutase (SOD), catalase (CAT), glutathione reductase (GR), monodehydroascorbate reductase (MDHAR) and dehydroascorbate reductase (DHAR) activities, ascorbate (ASC), dehydroascorbate (DHA) and glutathione (GSH) contents, non-photochemical quenching (NPQ) when compared to the control. In case of artificial prevention, antioxidant system and photosynthesis were inhibited. These results imply that leaf rolling is an important mechanism for the sustainability of photosynthesis under drought stress.