| Drought is a serious and universal problem of China, which restricts agriculture and forestry development. So researches of plant reaction on water stress plant's drought-fighting capability and how improve plant's drought-resistance capability are very important. Based on Castanea mallissima 2?? Cyclobalanopsis myrsinaefolia and Cyclobalanopsis glauca, this article studies some physiological and biochemical index' s changes of three species on water stress, such as contents of chlorophylK carotenoid and solute protein, the activities of kinds of protective enzymes(SOD,POD,CAT,ASP), O 2 producing rate, contents of H2O2, and MDA, membrane relative permeability and some water physiological indexes. This article also studies the pole of Spnu Ca2+, AsA about protecting cells and drought-resistance on water stress. At the same time, the article discusses the active oxygen metabolism and protective poles for chestnut of Spnu Ca2+, AsA on water stress. POD is an important enzyme which can adjust plant' growth and development and resist drought etc. So this article also research POD enzyme's kinetic characteristic of chestnut leaves primarily for future's research. The article is involved in:1. On using PEG6000 to deal with chestnut leaves, when stress-time and stress-intensity add, chestnut leaves tissue water content and free water content drops and bound water content adds; protein content drops; activities of superoxide dismutase(SOD)> peroxidase(POD) firstly descend, then ascend and lastly descend; Catalase(CAT) activity firstly rises and then drops; ascorbate peroxidase(ASP) activity has a descending trend; H2O2 content rises and superoxide anion radicals( O2) producing rate has a fluctuant change; Both malondialdedyde(MDA) content and membrane relative permeability have an ascending trend, yet MDA content descends in the last time. On the soil water stress, its each guideline's changes are similar to PEG6000 simulative water stress, but the chlorophyll content that has a descending trend is different from PEG6000 simulative water stress.1. In Cyclobalanopsis myrsimaefolia's research on water stress, when stress-time and stress-intensity add, tissue water content drops continually, transpiration rate firstly goes up and then drops, chlorophyll content firstly descends and then ascends and the protein content has trend of descending. The activity changes of SOD-. POD firstly ascend and then descend basically but CAT activity descends continually, MDA content and membrane relative permeability ascend continually and MDA content descends appreciably on the middling water stress in the last-time.3. In Cyclobalanopsis glanca's research on water stress, when stress-time andstress-intensity add, tissue water content drops, transpiration rate firstly goes up and then drops but chlorophyll content has an anomalous change; Both protein content and activities of SOD, POD have trend of firstly rising and then dropping, the POD activity fluctuates evidently on different stress intensity. CAT activity firstly ascends and then descends on low-grade stress intensity and has a lower value than comparison on medium- and high-grade stress intensity. Both MDA content and membrane relative permeability have an ascending trend.4. When Spnu Ca2+ and AsA deal with chestnut leaves on water stress, result indicates they make the protein and chlorophyll contents' reducing rate lessen and improve membrane stability; they also keep a high level of carotenoid content and activities of SOP, POD, CAT and lessen MDA content increasing rate and they inhibit the over-oxidation reaction and enhance the chestnut's drought-resistance capability.5.The result, which studies POD kinetic characteristic of chestnut leaves, indicates that the POD optimum temperature is 38 ℃ and the optimum pH is 4.6 and optimum HaO2 concentration is 0.1% and Km value is 128.17mmol/L and Vmax value is 281.68U/s.gFW. (HjNiCS and NaHSOj can inhibit POD activity and CaCl2 and KNO3 can motivate the POD activity.It is evidence that a great deal o...
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