Alterações fisiológicas em sementes de gergelim (Sesamum Indicum L.) armazenamento, estresse hídrico e salino

Abstract

The sesame (Sesamum indicum L.) is an oilseed very cultivated under rainfed conditions and represents for the producers of the Brazilian Northeast an income alternative, due to its tolerance to the edaphoclimatic conditions of the region. The research was carried out at the Seed Analysis Laboratory and at the Biotechnology Laboratory, both, from the Federal Rural University of Pernambuco / Garanhuns Academic Unit (UFRPE / UAG) in order to verify physiological and biochemical changes in sesame seeds, cultivar Anahí. , stored and also subjected to water and saline stress. Three experiments were performed; In the first, the seeds were placed in three packages (cloth, paper and tin) and stored in three environments (laboratory, freezer and refrigerator) for 12 months. Before and after each storage period, the physiological and biochemical characteristics were evaluated: determination of moisture content, germination, germination speed index, length and total dry mass of seedlings, catalase (CAT) enzyme activities, ascorbate peroxidase ( APX) and superoxide dismutase (SOD). In the second experiment, he evaluated the effect of water stress using polyethylene glycol (PEG 6000) solutions with osmotic potentials of 0.0 (control); -0.2; -0.4; and -0.6 MPa. In the third experiment, the effect of saline stress using sodium chloride (NaCl) was evaluated at five levels of salinity: 0.0 (control); -0.1; -0.2; -0.3; -0.4 Mpa. To evaluate water and saline stresses, germination percentage, germination speed index, total length and dry mass of seedlings and biochemical analyzes (chlorophylls, carotenoid, total soluble sugars) were computed. The storage of sesame seeds, cultivar Anahí, can be carried out in refrigerator and freezer environments, packed in a tin box for twelve months to maintain the physiological quality of the seeds. The activities of the enzymes Catalase, Ascorbate peroxidase and superoxide dismutase can be used as tools to indicate the deterioration of stored sesame seeds. Sesame seeds drastically reduce the physiological quality of their seeds and photosynthetic pigments in water potential simulated with polyethylene glycol from -0.4 MPa. Germination, vigor, chlorophyll, carotenoids, total soluble sugars contents decrease markedly from the -0.3MPa potential simulated with NaCl.