中文摘要：

为了探讨C4植物碳同化和光呼吸的电子效率,运用Li-6400光合仪同时测定玉米和高粱在30℃和380μmolCO2mol-1下叶片的气体交换和叶绿素荧光,结果表明,直角双曲线修正模型可较好地拟合所测的光响应曲线和快速光曲线,其拟合值与实测值较为一致。在此基础上算得玉米和高粱在光呼吸条件下参与碳同化的电子流分别为198.60μmolm-2s-1和178.00μmolm-2s-1,所占比率分别为75.34%和74.81%;参与光呼吸的电子流分别为7.04μmolm-2s-1和7.84μmolm-2s-1,所占比率分别为2.67%和3.29%。而根据Valentini和Epron的方法算得玉米和高粱碳同化的电子流分别为217.92μmolm-2s-1和188.54μmolm-2s-1,所占比例分别为82.68%和79.24%;参与光呼吸的电子流则分别为45.67μmolm-2s-1和49.40μmolm-2s-1,所占比率分别为17.32%和20.76%。以前法研究表明,玉米和高粱在光呼吸条件下,来自PSII的电子除流向光呼吸和碳还原外,还存在其他消耗电子的途径,证明其他消耗电子的途径并不能被忽略或其他途径所消耗电子的量并不是常数。后法过高地估算了玉米和高粱叶片中来自PSII的电子用于光呼吸的消耗量。两法的结果相差6倍左右。这对重新评估光呼吸在植物的光保护中所起的作用提供了理论依据。

英文摘要：

Gas exchange and chlorophyll fluorescence for maize （Zea mays L.） and sorghum （Sorhum bicolor L.） at 380 μmol CO2 mol 1 and 30℃ under photorespiratory condition, using a gas analyzer Li-6400, were measured. The results showed that the light response curve and rapid light curve （RLC） were well simulated by a modified rectangular hyperbola model. Calculation based on the simulated results indicated the electron flows to fix CO2 for maize and sorghum were 198.60 and 178.00 μmol m 2 s 1, with the rate of 75.34% and 74.81%, respectively. The electron flows in photorespiration of maize and sorghum were 7.04 and 7.84 μmol m 2 s 1, with the rate of 2.67% and 3.29%, respectively. While by method of Valentini and Epron, the electron flows to fix CO2 of maize and sorghum were 217.92 and 188.54 μmol m 2 s 1, with the rate of 82.68% and 79.24%, respectively, and those in photorespiration of maize and sorghum were 45.67 and 49.40 μmol m 2 s 1, with the rate of 17.32% and 20.76%, respectively. The results obtained by the former method showed that some electrons via PSII were used to CO2 assimilation and photorespiration, whereas others associated with electron-consuming processes （e.g. O2 acceptor cycle or water-water cycle） which should not be ignored, and the electron-consumption in this process was not constant under photorespiratory conditions. While the electron flows via PSII in photorespiration of maize and sorghum were overestimated by the latter method. The value of electron flows in photorespiration calculated by the latter method was about six times higher than those by the former. This is very important to evaluate the effect of photorespiration for plant protection.