日光温室草莓光合特性及对CO2浓度升高的响应

 运用美国LI-COR 公司制造的LI-6400 便携式光合作用测定系统, 研究了日光温室草莓盛果期的光合特性及对CO₂ 浓度升高的响应。结果表明, 叶片净光合速率(Pn) 日变化呈双峰型, 有明显的“光合午休”现象, 第1 个峰值出现在10 时左右, Pn 达到CO2 13. 1μmol·m^-2·s^-1; 第2个峰值出现在16 时,Pn 为CO₂ 9. 5μmol·m^-2·s^-1。造成光合午休的主要原因为气孔因素, 中午光照强度最大, 叶片与空气之间的水蒸气压差、气孔限制值达到最大值, 空气相对湿度、气孔导度、胞间CO₂浓度达到最小值, 出现光合午休。在CO₂浓度低于600μmol·mol^-1, 光照强度为1 000μmol·m^-2·s^-1时, 草莓CO₂饱和点为943. 3μmol·mol^-1, CO₂补偿点为91. 7μmol·mol^-1, Pn 高于光强更高者。

Changes of Photosynthetic Characteristics and Response to Rising CO2 Concentration in Strawberry in Solar Greenhouse

The LI-6400 Portable Photosynthesis System of LI-COR was used to study the photosynthetic characteristics of strawberry and its response to the rising CO₂ concentration at the full2fruit stage in the solar greenhouse. The results showed that the daily variation of net photosynthetic rate in leaves presented a bimodal curve and an obvious‘midday depression’phenomenon occurred. The first peak value was the highest , which occurredat about 10 : 00 am , the net photosynthetic rate was CO₂ 13. 1μmol·m^-2·s^-1, the second peak value occurred at 16 : 00 pm , the net photosynthetic rate was CO₂ 9. 5μmol ·m^-2·s^-1. The main reason for the middaydepression was stomatal factors.At midday ,light intensity was the largest ,vapor pressure deficit between leaves and air as well as stomatal limiting value reached maximum but air relative humidity , stomatal conductance and intercellular CO₂ concentration reached minimum and hence occurred photosynthetic midday depression. When light intensity reached 1 000μmol ·m^-2·s^-1 and CO₂ concentration was lower than 600μmol ·mol^-1, its net photosynthetic rate was higher than that of the much higher light intensity.At such light intensity the CO₂ saturation point was 943. 3μmol·mol ^-1 and CO₂ compensation point was 91. 7μmol·mol^-1.