不同生长季节光照强度和温度对柠条叶片光合作用和呼吸作用的影响

EFFECTS OF LIGHT INTENSITY AND TEMPERATURE ON PHOTOSYNTHESIS AND RESPIRATION IN LEAVES OF CARAGANA KORSHINSKII KOM DURING DIFFERENT GROWTH SEASONS

表观光合速率在夏季高于秋季并随光照强度增加递增，光饱和点、光补偿点和饱和光下的ＣＯ２补偿点夏季高于秋季，而呼吸作用和叶绿素的含量则较低。这表明秋季叶片光合速率降低与叶绿素含量无关，除部分受呼吸作用影响外，可能还受其它因素的影响。表观光合速率和真光合速率在２５℃时最高，随处理温度升高迅速递降，而呼吸速率则递增。延长温度的处理时间，光合作用和呼吸作用的变幅增大，秋季比夏季明显。这些结果表明，柠条叶片的光合作用和呼吸作用对温度敏感而不耐高温。

Effects of light intensity and temperature on photosynthesis and respiration in leaves ofCaragana Korshinskii Kom . were studied during different growth seasons. The apparent photosynthetic rates in summer were higher than those in autumn under different light intensity and they increasedwith the rise of light intensity. Light saturation point, light compensation point, and CO2compensationpoint under saturated light conditions in summer were higher than in autumn, while respiratory rateand chlorophyll content were lower. It indicated that the decrease of photosynthetic rate was notrelated to the chlorophyll content in autumn. It might be involved in other physiological factors inaddition to the partial influence of respiration.The apparent and ture photosynthetic rates were highest in leaves under 25 ℃, But theydecreased sharply with the increase of the temperature. Meanwhile, respiratory rate rised graduallywhen the temperature increased and the degrees of change were wider with increasing treatment time.The changes of photosynthesis and respiration in autumn were much greater than those in summer.These showed that they were sensetive and not tolerated to higher temperature.