Study On Photosynthesis Of Two Classical Ecosystems In Ebinur Lake Basin

This thesis is a study about two different classical ecosystems in Ebinur Lake:Agroecosystem and ilagroecosystem.It chooses Cotton Corn and phragmites australis in these two ecosystems which are classical and standard plants to inspect.Cotton and Corn are typical economical crops.And phragmites australis is a plant that adapt strongly and distrubute wildly.The study is mainly through two investigations,one investigation is about field and another is about the growth of Cotton and Corn in June and Sepetember.Then this study made use of the open gas exchange system, Li-6400 Portable Photosynthesis System, was carried on the research on Cotton Corn and phragmites australis's photosynthetic rate(Pn),transpiration rate (E) and water use efficiency (WUE) . The research studied the changes of Cotton Corn and phragmites australis's gas exchange parameters in the pressure of water and the changes of some kinds of important photosynthetic physiological factors and the physiological factors to deal with arid environment.The results showed that:(1) Representatives plant of agro-ecosystem, all of the Pn of cotton day changed emerged in bimodal curve either in June or in September. The process of change from the whole day to analyze the photosynthetic rate in June is far greater than the photosynthetic rate in September, and peaked during the period is not exactly the same as in June two peaks appeared at 13:00 and 17:00, in September two peaks appear in the 13:00 and 16:00.(2) Representatives plant of non-agro-ecosystem is phragmites australis. And the photosynthetic rate of phragmites australis change in June showing a single peak curve, that is, inverted "V"-type. There is only one peak appears in the photosynthetic 14:00, at the peak value of both sides of the photosynthetic rate of change is the asymmetry, the left side of the peak value of the starting point on the phragmites australis of the photosynthetic rate is relatively high, the middle does not appear the phenomenon of midday depression of photosynthesis.(3) September phragmites australis photosynthetic rate and transpiration rate day changes, net photosynthetic rate showing a clear bimodal curve, diurnal variation of transpiration rate first increased and then decreased showing irregular inverted "U" curve. Net photosynthetic rate of Phragmites australis in September peak appeared at 13:00 and 15:00. September reed diurnal variation of photosynthetic rate is very uniform, there was no dramatic increase or decrease.(4) There are many factors affect the agro-ecosystem and non-agro-ecosystem net photosynthetic rate, including plants also have their own genetic factors of the ecological factors associated with the outside world. Plant's own genetic factors are: stomatal conductance, intercellular CO2 concentration and leaf temperature, etc.; and the impact of external factors are: temperature, humidity, light, wind speed and so on.(5) the correlation of cotton's own research which impact of cotton in the net photosynthetic rate of factors shows that: cotton's own main factors the impact of net photosynthetic rate of cotton are stomatal conductance, intercellular carbon dioxide concentration and leaf temperature, in which stomatal conductance and leaf temperature and net photosynthetic rate of the relevance of the best. the environmental factors affect the net photosynthetic rate of cotton,are mainly water, light. These include: the transpiration rate, the value of pressure deficit, temperature, carbon dioxide, water, light intensity and air humidity. These factors and net photosynthetic rate showed a highly significant positive correlation is: transpiration rate, temperature, water; their relevance respectively of 0.931,0.865 and 0.933. Showed significantly related to the environmental factor is light intensity, correlation is 0.513.(6) In all factors of phragmites australis itself that affect the net photosynthetic rate, only the stomatal conductance and net photosynthetic rate showed a significant correlation and the correlation coefficient is 0.720.In the factors that affect the net photosynthetic rate of phragmites australis eco-environmental, only the light intensity and the net photosynthetic rate has shown a significant correlation and the correlation coefficient is 0.555. The other impact relevant factors are: humidity, transpiration rate, pressure deficit values as well as the air temperature.(7) During stepwise regression analysis of influencing factors, whether cotton or phragmites australis, the first step into the regression model were stomatal conductance, indicating stomatal conductance of cotton and phragmites australis for the effects of changes in net photosynthetic rate is very important. Second, enter the regression model is the transpiration rate, due to changes in transpiration rate and stomatal changes are related closely.(8) Whether blades toward or leaf age, the protein content of phragmites australis were higher than cotton, sugar content higher than cotton, but the MDA content in the low than cotton, indicating resilience phragmites australis worse than that of cotton ,and phragmites australis further clarify adaptability, viability strong.