清香梨幼树和成年树光合特性比较研究

用CIRAS-1便携式光合作用测定系统测定了清香梨幼树和成年树叶片的光合特性,结果表明:清香梨幼树叶片的净光合速率(Pn)、气孔导度和蒸腾速率显著高于成年树,而幼树和成年树叶片的胞间CO2浓度(C i)、气孔阻止值和水分利用率差异不显著。在低光强、低CO2浓度(Ca)或低C i下,梨幼树和成年树叶片的Pn差异较小,但随着光强、Ca或C i的增加,两者间Pn的差异明显加大。幼年树叶片的光补偿点、光饱和点、CO2补偿点、CO2光饱和点、表观量子效率、羧化效率、光合能力和RuBP最大生产速率均高于结果树。

Comparative Study on Photosynthesis Characteristics between Young Tree and Bearing Tree of Qingxiang Pear

The photosynthesis characteristics between young tree and bearing tree of Qingxiang pear(Pyrus pyrifolia Nakai cv.Qingxiang) were measured by portable photosynthesis system CIRAS-1.The results showed that,the net photosynthetic rate(Pn),the stomatal conductance and the transpiration rate of young tree were significantly higher than those of bearing tree,but the other photosynthesis and physiological indexes including the intercellular CO2 concentration(Ci),the stoma limit ratio and the water use efficiency between young tree and bearing tree were all not significantly different.Under weak light,low CO2 concentration(Ca) or low Ci conditions,there was little discrepancy in Pn between young tree and bearing tree,but the discrepancy was enlarged markedly along with increase of the light,Ca or Ci.The photosynthesis physiological indexes including the light compensation point,the light saturation point,the CO2 compensation point,the CO2 saturation point,the appearance quantum yield,the carboxylation efficiency,the photosynthetic capacity and the max regeneration rate of RuBP of young tree were all higher than those of bearing tree.