Study On The Photosynthetic Physiological Characteristics Of Cold-resistant Eucalyptus In Jiangxi Province

In this paper, to filter out four cold-resistant five-year growth Eucalyptus,such as E.camaldulensis,E.camphora, E.dunnii, E.dorrigoensis as experimental materials, use the machine which produced by the United States portable Li-6400 photosynthesis system on the physiological characteristics of Eucalyptus systematically determined. Determined content: diurnal photosynthetic indexes, seasonal dynamics and the response of photosynthesis to light intensity; And chlorophyll content were analyzed; survey base status and low temperature and freezing the growth of Eucalyptus situation. Comprehensive use of analysis of variance and regression analysis were used to reveal the photosynthetic physiological characteristics of cold Eucalyptus and the relationship between nature and speed, suitable for the selection of both cold and Jiangxi growth of fast-growing varieties provide a scientific basis for improving the photosyntheticEucalyptus Capacity and productivity to provide reference. The results showed that:(1) Four kinds of eucalyptus in different seasons cold diurnal variation type is a single peak and double peak, double peak curve is mainly due to different levels of photosynthetic midday depression.Eucalyptus daily average photosynthetic rate of four in the order of E.camaldulensis >E.dunnii>E.dorrigoensis>E.camphora. Four cold resistant Eucalyptus Pmax of the maximum net photosynthetic rate ranged from 14.1CO2μmol.m-2.s-1 to 21.99CO2μ.mol.m-2.s-1.Eucalyptus cam aldulensis average Pmax was significantly large than the other three eucalyptus.(2) Four cold resistant Eucalyptus range of light saturation point is 1570μmol.m-2.s-1-1900μm ol.m-2.s-1, E.camaldulensis, E.dunnii and E.dorrigoensis basically concentrated in the 1600μmol.m-2.s-1 between the different months only slight fluctuations.Four Eucalyptus's ligh t compensation point in different months are not the same, its range is 11μmol.m-2.s-1-33μmol.m-2.s-1.(3) The average daily transpiration rate of the order:E.dunnii> E.camphora> E.camaldulensis> E.dorrigoensis. Transpiration rate are single-peak curve,E.dunnii exhibited a strong drought resistance and the ability of adaptation to the environment.Intercellular CO2 concentration of four Eucalyptus diurnal variation in the general radiate "U" type, resulting in E.dorrigoensis and E.camaldulensis midday depression of photosynthesis is due to stomatal factors.Four daily average water use efficiency of Eucalyptus in the order of: E.camaldulensis>E.dunnii>E.dorrigoensis>E.camphora(4) In different months in different net photosynthetic rates of Eucalyptus cold resistant there are obvious differences, but the net photosynthetic rate of four Eucalyptus overall trend is consistent with seasonal changes, Order is:July> September> December(5) Four cold resistant Eucalyptus transpiration rate of the average seasonal variation of the order is: July> September> December;Seasonal changes in the average water use efficiency in the order of: December> September> July.(6)The total chlorophyll's average is in the order of: E. camphora >E. camaldulensis> E. dorrigoensis> E.dunnii..Research about Chlorophyll a, chlorophyll b, total chlorophyll, chlorophyll a/ b and photosynthetic rate show that photosynthetic rate of four Eucalyptus was no significant correlation with chlorophyll.(7) Eucalyptus cold resistant strengths and weaknesses are:E. dunnii>E.dorrigoensis>E.camph ora>E.camaldulensis.Howerer, the ranking of four Eucalyptus's average value Pn in Winter is E. camaldulensis> E.dorrigoensis> E. dunnii> E.camphora:Photosynthesis and cold tolerance of fo ur Eucalyptus are not significant correlation Related ordinal is P= 0.1232(8)Photosynthetic capacity and growth rate of Eucalyptus is closely related, the average diameter of four Eucalyptus and tree height in the order is:E. dunnii>E.camaldulensis> E.dorrigoensis> E.camphora, The ranking of four Eucalyptus's photosynthetic rate is basically the same order of growth rate. Photosynthetic rate and the average DBH, tree height, the correlation coefficient is 0.9634 and 0.9962, respectively.