| In order to explore the effects of different concentrations of extraneous spermidine(Spd) on the drought resistance of oat seedling,under water stress simulated by PEG-6000,“Bayou 1” ,an oat variety,was used as the material with sand culture methods under different concentrations of extraneous spermidine (0.3 mmol·L-1, 0.6 mmol·L-1, 0.9 mmol·L-1, and 1.2 mmol·L-1）to study its effects on oat seedling growth, reactive oxygen species metabolism and the content of antioxidant enzymes and osmotic regulation substances. The results showed that osmotic stress significantly inhibited the growth of oat seedlings. Exogenous Spd with concentration of 0.6 mmol·L-1 application significantly promoted root activity, ASA and APX contents of oat seedlings. Exogenous Spd with concentration of 0.9 mmol·L-1 application significantly increased plant height, root length and biomass accumulation, but inhabited the formation of O-·2, H2O2 and MDA and induced to enhance the activities of SOD, CAT, POD and GR in antioxidant system. Moreover, the total amount of free amino acid was reduced and the accumulation of proline, soluble sugar and soluble protein of organic solutes were promoted, and finally maintained a high osmotic buffer and adjustment capability. Exogenous Spd with concentration of 1.2 mmol·L-1 application showed a decreasing trend in physiological responses. According to the physiological and biochemical indices, under water stress, extraneous 0.9 mmol·L-1 Spd could protect the stability of the biological membrane system through the promotion of anti-oxidase activity and ascorbic acid (ASA), glutathione (GSH) content. The damage caused by water stress was reduced, while the drought resistance of oat seedlings was enhanced. |
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