Effects Of Ethephon On The Photosynthetic Characterstics And Senscence Of Peanut

Different concentrations of ethephon were sprayed on leaves of peanut at early flowering stage in the experiment. The plant growth was investigated. Some physiological and biochemical and gas exchange and chlorophyll fluorescence characteristics in peanut function leaves were determined at different stages. Changes of some physiological and biochemical characteristics in relation to senescence in the leaves were also analyzed. The main results were as follows:1.The 200mg/L ethephon treatment increased the contents of photosynthetic pigment in leaves and delayed the decrease of them at the late stage as compared with the control. The ethephon treatment also increased the contents of soluble protein, the activities of peroxidase (POD) and superoxide dismutase(SOD), and decreased the contents of malondialdehyde (MDA) in leaves of peanut at the late stage.2. The ethephon treatment increased the net photosynthetic rate in peanutleaves at the late stage, and increased the net photosynthetic rate but not did change the single peak figure in the diurnal change.The best performance was observed in the 200mg/L ethephon treatment among all based on a comprehensive consideration.3. The ethephon treatment decreased the Fo and increased the Fv/Fo, quantum yield and the ratio of the opening active centers to the total. In the diurnal change of the chlorophyll fluorescence, it also decreased the Fo and increasd the Fv/Fo.4. Based on the changes in the physiological and biochemical characteristics including the contents of chlorophyll, soluble protein and malondialdehyde (MDA), and the activities of peroxidase and superoxide dismutase, and the photosynthetic characteristics in the tag leaves, the ethephon treatment was effective to delay the senescence of the leave.5. The 200mg/L and 300mg/L ehtephon treatment significantly increased the total branches and plant heightof peanut plants as compared with the control. And the 200mg/L ethephon treatment also increased the rate of plump pods, weight of dry pods, weight of 100 pods and weight of 100 seeds, but the 300mg/L ethephon treatment decreased the rate of plump pods and weight of 100 pods.