Research on leaf photosynthesis and chlorophyll fluorescence parameters of two C4 crops at different leaf position | 两种C4作物不同叶位光合及叶绿素荧光特性比较

Chinese. 为探明同为C4植物的玉米和高粱抽雄期叶片光合生理的差异,对两种植物不同叶位相对叶绿素含量、光合生理特性、叶绿素荧光特性参数进行比较研究。结果表明：在该生育期,玉米上部叶位叶片SPAD值显著（P〈0.05）高于高粱,下、中部叶位差异不显著（P〉0.05）;玉米不同叶位净光合速率（Pn）、水分利用效率（WUE）和光能利用效率（LUE）等光合参数显著高于高粱,不同叶位上玉米表现较强的光响应能力,玉米不同叶位羧化速率（CE）和CO2饱和点（Cisat）分别比高粱高13.29%和29.33%;对比不同叶位实际光化学效率（ΦPSⅡ）和光化学猝灭（qP）,玉米显著高于高粱,但初始光能转化效率（Fv/Fm）差异不显著（P〉0.05）。由此可见,玉米的光合适应性能强于高粱,其光合系统对环境有效光合辐射利用能力高于高粱。

English. Both maize and sorghum are C4 crops while their abilities of photosynthesis in the tasseling stage are different.The study was carried out to investigate the relative chlorophyll content,photosynthesis and chlorophyll fluorescence parameters of leaves at three different positions of the two crops.The results indicated that for the upper leaf,the relative chlorophyll content（SPAD） of maize in this period was significantly（P0.05）.For leaves at three different positions,net photosynthetic rate（Pn）,water use efficiency（WUE）,and light use efficiency（LUE） in maize were significantly higher than sorghum.The mean CO2 saturation point（Cisat） and carboxylation rate（CE） of maize are 13.29% and 29.33% higher than sorghum at the three different leaf positions,respectively;indicating better light response capability of maize than that of sorghum.For leaves at three different positions,the actual photochemical coefficient（ΦPSⅡ） and photochemical quenching（qP） of maize were significantly higher than sorghum,while the difference in initial energy conversion coefficient（Fv/Fm） was not significant（P〉0.05）.It was therefore concluded that maize had a better photosynthetic adaptability than sorghum;the photosynthetic system of maize had much more advantages in using the photosynthetically active radiation in the field.