保护地黄瓜叶片光合作用温度特性的研究

Studies on Photosynthetic Temperature Characteristic of Cucumber Leaves in Protective Field

2年试验结果表明,保护地黄瓜叶片净光合速率的变化范围在9～22μmolCO_2m^(-2)s^(-1)之间。光合作用的最适温度为25～33℃;光合作用的温度下限为3～6℃;上限为42～44℃。黄瓜叶片光合作用对温度的反应受生长期间温度条件的影响,昼温为36℃下生长的叶片比28℃下生长的叶片表现为较高的耐高温特性。完全展开10天以内的叶片不仅光合速率高,对温度变化的反应也敏感;衰老(完全展开20天后)的叶片不仅光合速率低,对温度变化的反应也不敏感。 在低温条件下,黄瓜叶片的呼吸作用以及光合作用的光补偿点和光饱和点均较低,并随着温度的增加而增加。但光饱和点达到光合适温后不再增加,超过40℃时呼吸作用开始下降。叶片表观量子产额及光合与呼吸CO_2交换的比值在不同温度条件下呈单峰曲线变化,其峰值的温度低于或接近25℃。

The net photosynthetic rate of cucumber leaves in protective field was in the range of 9~22 μmol CO_2 m^(-2)s^(-1) during the two years. The optimum temperature of photosynthesis was 25~33℃. The lowest temperature of photosynthesis was 3~6℃ and the highest temperature was 42 ~ 44℃. The response characteristic of photosynthesis was affected by temperature conditions during the growth . Photosynthetic optimum tempera -ture of cucumber leaves grown in 36℃ (day temperature) was higher than those of grown in 28℃. Cucumber leaves within 10 days after unfolding had higher net photo-synthetic rate (15~21μmol CO_2 m^(-2)s^(-1)) and temperature quotient (1. 6 ~ 2. 1), the aging leaves (over 20 days after unfolding) had lower net photosynthetic rate (6~15μmol CO_2 m^(-2)s^(-1)) and temperature quotient (1. 1~1. 6). Lower respiration rate, light compensation point and light saturation point were measured in cucumber leaves under low temperature (6~15℃) and increased with the increase of the temperature. But respiration rate began decrease over 40℃, light saturation point did not increase when reach the optimum temperature. Higher ratio of photosynthesis to respiration were measured under 15 ~ 30℃. Apparent quantum yield showed a single peak curve change under different temperature, maxmum values were measured in 20~25℃.