冠层部位和叶龄对红松光合蒸腾特性的影响

Effects of canopy position and leaf age on photosynthesis and transpiration of Pinus koraiensis

利用Li-6400便携式CO2/H2O红外气体分析仪测定了红松不同冠层部位和叶龄针叶的光合蒸腾特性及其环境影响因子.结果表明:冠层部位和叶龄显著地影响最大净光合速率(Pmax)、光饱和点(LSP)、光补偿点(LCP)、表观最大量子效率(α)、蒸腾速率(Tr)和比叶面积(SLA),但对水分利用效率(WUE)影响不显著.随着冠层部位的下降和叶龄的增加,红松针叶的Pmax逐渐下降,其平均值变动在6·55～9·05μmol·m-2·s-1之间.不同冠层部位和叶龄针叶的LSP和LCP的差异很大,以树冠中部针叶对弱光和强光的利用能力最大.Tr随着冠层部位的下降而降低;不同叶龄针叶的Tr在1·37～1·59mmol·m-2·s-1之间变化.不同部位和叶龄红松针叶的Tr和光合有效辐射存在极显著正相关关系(R2=0·967).红松的WUE与净光合速率紧密相关(R2=0·860).随冠层部位的上升和叶龄的增大,红松针叶的SLA递减,分别在6·61～8·41m2·kg-1和6·65～8·38m2·kg-1之间波动.

The photosynthesis and transpiration of Pinus koraieasis needles at different canopy positions and of different leaf ages were measured in the field with a Li-6400 portable CO2/H2O infrared gas analyzer. The results showed that canopy position and leaf age had significant effects on the maximum net photosynthetic rate （Pmax） , light saturation point （LSP）, light compensation point （LCP）, maximum apparent quantum efficiency （α）, transpiration rate （Tr）, and specific leaf are- a （ SLA）, but no effects on water use efficiency （WUE）. The Pmax decreased with the decrease of canopy position and the increase of leaf age, ranging in 6.55-9. 05 μmol · m^-2 · s^-1 on average. There were great variations in LSP and LCP among different canopy positions and leaf ages. The needles at middle canopy position had the greatest capacity of utilizing both weak and strong radiation. The Tr decreased with canopy position decreasing, and varied from 1.37 to 1.59 mmol · m^-2· s^-1 across different leaf ages. There was a significant positive correlation between Tr and photo- synthetically active radiation （R^2 = 0. 967）, and between WUE and net photosynthetic rate （R^2 = 0. 860）. The SLA decreased with canopy position and leaf age increasing, ranging in 6. 61-8.41 m^2· kg^-1 and 6.65-8.38 m^2· kg^-1 , respectively.