三个红叶石楠品种光合特性的比较研究

Study on Photosynthetic Characteristics of Three Cultivars in Photinia×fraseri

利用CI-340便携式光合作用系统测定仪,在晴天条件下对三种红叶石楠品种火艳石楠（Photinia×fraseri’Camely’）、红罗宾石楠（Photinia×fraseri’Red Robin’）和小叶红叶石楠（Photinia×fraseri’Parvifolia’）的光合特性进行了比较研究.结果表明：（1）三个红叶石楠品种叶片的净光合速率（Pn）日变化均呈＂双峰＂曲线,在中午均有明显光合＂午休＂现象.通过对它们的净光合速率（Pn）日变化的比较研究,可知红罗宾石楠不耐强光.（2）三个红叶石楠品种的净光合速率、蒸腾速率和气孔导度的日平均值一致表现为：小叶红叶石楠〉火艳石楠〉红罗宾石楠,表明小叶红叶石楠在自然栽培条件下光合作用旺盛.（3）根据胞间CO2浓度（Ci）和气孔导度（Gs）的变化方向,推测三种红叶石楠品种的光合＂午休＂主要受非气孔因素限制.

Photosynthetic rate（Pn）,intercellular CO2 concentration（Ci）,stomatal conductance（Gs） and transpiration rate（Tr） of three cultivars in Photinia×fraseri were measured with CI-340 portable photosynthesis system under sunny conditions.The results showed that the diurnal changes of Pn in the three cultivars all exhibited ＂double peak curve＂ and ＂midday depression＂ at midday,indicating that Photinia×fraseri Redobin couldn’t bear burning sunlight;the orders of the diurnal averages of their Pn,Tr and Gs were all Photinia×fraseri ParvifoliaPhotinia×fraseri CamelyPhotinia×fraseri Redobin,which illustrated that the photosynthesis of Photinia×fraseri was the strongest in the natural cultivation conditions.Additionally,according to the changing directions of their Pn,Ci and Gs,we could infer that ＂midday depression＂ of the three cultivars was not related to stomata.