| The aim of the present study was to investigate the effect of y-radiation on plant growth and physiological responses of an aquatic plant, Zizania latifolia. The Z. latifolia seedlings during6-leaf stage were irradiated with25,50and100Gy of y rays of the60Co source, and growth parameters, chlorophyll contents, photosynthetic gas exchange, chlorophyll fluorescence, MDA content, antioxidant enzyme activities and antioxidant contents were determined at week interval after irradiation.The results showed that plant height, leaf number and tiller number were inhibited by the irradiation, especially from3rd weeks post irradiation. Chl a, Chl b, and Chi a+b contents were also decreased significantly after irradiation. The net photosynthetic rate, stomatal conductance, intercellular CO2concentration and transpiration rate were generally declined dose-dependently in irradiated plants especially3weeks later. As for the chlorophyll fluorescence parameters, Fv/Fm, ΦPSⅡ, qP and ETR were decreased significantly compared to control3weeks later, while NPQ increased significantly in plants irradiated by100Gy.The MDA content increased after irradiation suggesting occurrence of oxidative stress in plant tissues. The activities of almost all the antioxidant enzymes decreased in the irradiation plants in the most weeks post irradiation except APX, whose activity was increased, while the AsA and GSH contents were all increassed after irradiation, which indicating a possible protective mechanism of Z. latifolia plant against oxidative stress.Based on the results obtained, we conclude that the plant performance and physiological responses of Z. latifolia plant were greatly influenced by60Co y irradiation, especially under the high dose. |
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