普那菊苣夏季光合速率日变化及其影响因子的研究

Study on the Diurnal Changes of Net Photosynthetic Rate and the Impact Factors of Puna Chicory in Summer

研究夏季普那菊苣叶片净光合速率日变化及其与影响因子的相互关系。利用CI-340便携式光合仪,测定了普那菊苣叶片净光合速率和环境因子(气温、光合有效辐射、空气相对湿度)、生理因子(蒸腾速率、胞间CO2浓度、气孔导度)的日变化;通过回归和通径分析,考察了影响因子对净光合速率日变化的影响。结果表明,在夏季自然晴天下,普那菊苣叶片的净光合速率呈双峰曲线,表现出"光午休"现象,保护性气孔导度降低,是高光强、高温下高光呼吸所致。

Relationship between diurnal changes of net photosynthetic rate （Pn） and the impact factors in leaves of Puna Cichorium intybus were studied. Diurnal changes of Pn and environmental factors （photosynthetic available radiation and air temperature and relative humidity） and physiology factors （stomatal conductance and transpiration rate and intercellular CO2）in leaves of puna chicory were measured using CI-340 portable photosynthesis system. The relationship between Pn and environmental factors were analyzed by regression analysis and path analysis. The results showed that the curve of diurnal changes of Pn was demonstrated two peaks in clear day and appeared ＂photosynthetic depressed＂ in the noon, and the stomatal conductance decreased. All those were due to high photorespiration which was caused by high light intensity and high temperature.