澳州坚果叶片光合速率和叶绿素荧光参数日变化

DIURNAL CHANGES OF PHOTOSYNTHETIC CHARACTERISTICS AND CHLOROPHYLL FLUORESCENCE IN MACADAMIA INTEGRIFOLIA

以澳洲坚果为材料,研究其叶绿素荧光动力学参数和净光合速率及其光合有效辐射、温度、空气湿度、大气二氧化碳浓度、蒸腾速率等影响因子。结果表明:澳洲坚果光合速率日变化呈不对称的双峰曲线,有明显的“午休”现象;第1个峰值出现在7∶00,净光合速率达到5.22μmol/(m2.s),第2个峰值出现在14∶00,净光合速率达到4.18μmol/(m2.s)。影响光合作用的主导环境因子为光照强度和湿度。Fv/Fm和Fv/Fo均表现出先下降后上升的趋势,光合活性受到暂时抑制,光合器官并没有受到损伤。

The kinetic parameters of chlorophyll fluorescence and the photosynthetic characteristics of Macadamia integrifolia, and the affecting factors for PAR （ photosynthetic active radiation）, temperature, air humidity and CO2 content and transpiration rate were studied. The results showed that the diurnal variation of net photosynthetic rate in the leaves presented a bimodal curve, and an obvious phenomenon of ＂mid-day depression＂ occurred. The first peak, which occurred around 7 ：00 a. m. , was higher, with a net photosynthetic rate of 5.22 μmol/（m2· s）. The second peak, occurring around 14 ： 00 p. m. , had a net photosynthetic rate of 4. 18μmol/（m^2·s）. The main reason for the mid - day depression was PAR and relative humidity. The primary light energy conversion of PSⅡ （ Fv/Fm ） and potential avtivities of PSⅡ （ Fv/Fo） decreased with increasing PAR. The values of both Fv/Fm and Fv/Fo dropped first, followed by a rise, indicating that photosynthetic activity was only temporarily inhibited while the photosynthetic organs were not injured.