Comparative Study On Photosynthesis Physiological Characteristics And Annual Variety Of Leaf Nutrient Of Three Phoebe Plants

Photosynthesis is the process in which the green plants use light energy to transform its energy and form organic substance. The process may be changed by environmental conditions. This study mainly tests the four following aspects. Firstly, it tests the net photosynthetic rate of Machilus leptophylla Hand.-Mazz and Phoebe zhennan S.Lee et F.N.Wei. in Zongyang County and Phoebe sheareri Hemsl. Gamble in Anhui Agricultural University in four different seasons by use of LI-6400 portable photosynthetic system produced by the LI-COR Company US. Secondly, the photosynthesis lightresponse curves of the three phoebe plants were tested in order to analyze the genetic controls on tue net photosynthetic rate. Thirdly, it measures the chlorophyll content and the rate of weight to area and analyzed the shade-tolerance nature of the three phoebe plants. Fourthly, it measured the nutrient content of the three phoebe plants'fresh leaf and withered leafage and analyzed the relationship between net photosynthetic rates. The main results are as follows:1. Under natural circumstances, the three phoebe plants'net photosynthetic rate has two different types in different seasons. Two-peak curve was observed in summer and autumn and one-peak curve in spring and winter. Based on the maximum net photosynthetic rate and average daily net photosynthetic rate, the sequence of the three phoebe plants renked as Phoebe sheareri > Phoebe zhennan > Machilus leptophylla.2. By analyzing the photosynthesis lightresponse curve, Machilus leptophylla and Phoebe zhennan showed a lower light-compensation point(10.89μmol/m~2·s,15.93μmol/m~2·s). Phoebe sheareri showed a relatively higher light-saturation point(1100μmol/m~2·s).3. In combination with All-through analysis and progressively-regression analysis, the main controls on net photosynthetic rate were photosynthetically active radiation (PAR), atmosphere temperature (Ta), stomatal conductance (Cond), transpiration rate (Tr) and leaf water deficit (Vpdl). These factors have complexity and instability when they impact net photosynthetic rate.4. In different seasons, the three phoebe plants do not have a distinct change rule in the event of water use efficiency (WUE), while the light use efficiency (LUE) embodies as Winter > Summer> Autumn >Spring. The main genetic in summer is photosynthetically active radiation (PAR) and transpiration rate(Tr). 5. By analyzing the chlorophyll a content, chlorophyll b content and LMA of the three phoebe plants, the seasonal dynamic change of chlorophyll a/b is Autumn > Summer > Spring > Winter. Among the three, Machilus leptophylla has the least chlorophyll a/b (1.7256) and has a relatively strong shade-tolerance nature.The rate of weight to area (LMA) and net photosynthetic rate (Pn) are distinctively related, the correlation coefficients are 0.7678,0.8901 and 0.8777 .6. By measuring the three kinds of Phoebe plants'leaf nutrient concentrations in different seasons and analyzing the relationship between leaf feature parameter and net photosynthetic rate, the result showed that the phosphor us content (P) of Machilus leptophylla and Phoebe zhennan was strongly related to net photosynthetic rate, with correlation coefficients of 0.8283 and 0.819;1and the nitrogen content (N) of Phoebe sheareri was strongly related to net photosynthetic rate, the correlation coefficient is 0.7545.