Effects of Tetracycline on Seed Germination,Seedling Growth and Oxidative Damage of Four Leafy Vegetables
[Objective]The study aims to explore the effects of tetracycline (TC) stress on the growth and physiological characteristics of leafy vegetables,and to provide a theoretical basis for researches on the toxic effects of antibiotics on plants.[Method]Shanghai green,pakchoi,Chinese cabbage and lettuce were taken as experimental subjects. The simulated culture method was adopted in the laboratory. The effects of different concentrations of TC in soil (0-500 mg/kg) on the growth (germination rate,plant height,aboveground fresh weight) and physiological and biochemical indexes (chlorophyll,MDA,SOD,POD and CAT) of four vegetables were studied.[Result]The germination rate of the four tested vegetables gradually decreased with the increase of TC concentration,the plant height and aboveground fresh weight of Shanghai green and pakchoi gradually increased under TC stress at low concentrations (10,50,100 mg/kg),and gradually decreased under TC stress at high concentrations (300,500 mg/kg). The maximum value reached at 100 mg/kg TC treatment. The plant height and aboveground fresh weight of Chinese cabbage and lettuce decreased gradually with the increase of TC concentration. The chlorophyll contents of pakchoi,Chinese cabbage and lettuce increased under TC stress at low concentrations (10,50,100 mg/kg),while the chlorophyll content of Shanghai green decreased under TC stress. The MDA activity of four vegetables increased with the increase of TC concentration,and was significantly higher than that of control under 500 mg/kg TC treatment. The CAT activity of Shanghai green,lettuce and pakchoi was the highest under the treatment of 10 mg/kg TC,and the CAT activity of Chinese cabbage was the highest under the treatment of 50 mg/kg TC. The SOD activity of Chinese cabbage and Shanghai green was the highest at 100 mg/kg TC treatment,which was 21.12％ and 22.33％ higher than that of the control,while the SOD activity of pakchoi and lettuce decreased with the increase of TC concentration. The POD activity of Chinese cabbage,lettuce,Shanghai green and pakchoi was the highest at 10,50,100 and 500 mg/kg TC concentration,respectively,which was 0.85％,14.16％,8.20％ and 24.79％ higher than that of control.[Conclusion]The four vegetables exhibited different sensitivities to TC. TC inhibited the growth of cabbage and lettuce,while promoting the growth of Shanghai green and Chinese cabbage at low concentrations (10,50,100 mg/kg). However,under high concentrations (300,500 mg/kg),growth inhibition occurred,intensifying with the increase of TC concentration. High TC stress increased plant cell damage in all four vegetable species and led to damage in the antioxidant enzyme system.
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