| Using pepper leaf aqueous extracts as model of autotoxic substances in the continuous cropping obstacles, the effects of exogenous glutathione on pepper seedlings'physiological and biochemical characteristics under autotoxicity were explored. Growth index, photosynthetic characteristics and chlorophyll fluorescence parameters, antioxidant enzyme systems, antioxidants and endogenous phytohormones were studied after treatment. The main results were presented as follows:1. With the process of treatment, after treated with extracts of pepper leaf aqueous, the increase amplitude of plant height, stem diameter, leaf size and leaf number, the growth rate of leave length and width decreased as compared to water treatment, root activity was decreased significantly compared with other treatments. When seedlings were treated with different concentrations of glutathione, the increase amplitude of plant height, stem diameter, leaf size and leaf number, the growth rate of leave length and width increased compared with treated by aqueous leave extracts only and the untreated as well, root activity was significantly increased.2. After treated with 50g·L-1 extracts of pepper leaf aqueous, comparing with water treatment, the chlorophyll content, net photosynthetic rate, stomatal conductance and transpiration rate were decreased, but intercellular CO2 concentration was increased significantly. With the passage of time, the chlorophyll content, net photosynthetic rate, stomatal conductance and transpiration rate were increased, while intercellular CO2 concentration was decreased significantly under different concentrations of glutathione compared with treated by aqueous leave extracts only and the untreated as well.3. With the passage of treatment time, after treated with extracts of pepper leaf aqueous, maximal PSII efficiency, maximal PSII efficiency at open centers in the presence of NPQ, actual photochemical efficiency of PSII in the light decreased, but origin fluorescence was increased significantly compared with water treatment. When the plants were treated with different concentrations of glutathione, the maximal PSII efficiency, maximal PSII efficiency at open centers in the presence of NPQ and actual photochemical efficiency of PSII in the light were increased, while origin fluorescence was decreased significantly compared with treated by aqueous leave extracts only.4. When treated with extracts of pepper leaf aqueous, the activities of superoxide dismutase, peroxidase, ascorbate peroxidase were decreased significantly, while malondialdehyde content was increased. The activities of glutathione reductase and content of glutathione were increased firstly and then decreased, but ascorbic acid decreased apparently. As the passage of time, the activities of superoxide dismutase, peroxidase, ascorbate peroxidase, glutathione reductase, the contents of glutathione and ascorbic acid increased apparently, while the malondialdehyde content decreased under concentrations of glutathione were 30mg·L-1 and 50mg·L-1 added compared with treated by aqueous leave extracts only and the untreated as well.5. After treated with 50g·L-1 extracts of pepper leaf aqueous, two cultivars of abscisic acid content was a significant upward trend, indole acetic acid content dropped significantly compared with water treatment, the ratio of indole acetic acid and abscisic acid of two cultivars decreased with the passage of time. To a certain extent, compared with treated by aqueous leave extracts only and the untreated as well, after treated with different concentrations of glutathione could increased indole acetic acid content and decreased abscisic acid content of the two cultivars, but the ratio of indole acetic acid and abscisic acid increased with the increasing of glutathione concentrations.6. The integrated effect factor was used as a method to measure the effects of those different concentrations of glutathione under autotoxicity, which showed that the optimum for two cultivars is glutathione of 50mg·L-1.
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