西藏林芝云杉针叶净光合速率对环境因子的响应

Response of Linzhi Spruce's Net Photosynthetic Rate to Environmental Factors in Tibet

使用便携式光合系统仪Li 6200测定了西藏林芝云杉净光合速率的日变化及其对环境因子如量子辐射、相对湿度和CO2浓度的响应。研究结果表明:林芝云杉的净光合速率在11:00点左右达到最大值,然后逐渐下降,到19:00点左右净光合速率降到0以下,转入暗呼吸。林芝云杉树冠上层的针叶由于受光充分,净光合速率较下层针叶大;阴生叶与阳生叶的净光合速率,上层差别不大,下层以阴生叶为大。在气温20℃左右、相对湿度70%±5%、CO2浓度为305mg·kg-1条件下,林芝云杉的光补偿点约为107 5μmol·m-2·s-1,光饱和点约为770μmol·m-2·s-1;在光强800μmol·m-2·s-1、气温20℃左右、相对湿度70%±5%条件下,林芝云杉的CO2补偿点约为157 2mg·kg-1,CO2饱和点约为3811 33mg·kg-1。

The daily change of net photosynthetic rate(NPR) and its response to environment factors such as quantum radiation, relative humidity and CO2 concentration of Linzhi spruce(Picea likiangensis var.linzhiensis) was monitored with a portable photosynthesis system. It is showed that the maximal NPR happened at 11:00, then the rate decreased and down below zero at about 19:00 in which Linzhi spruce entered dark respiration. NPR of top and outlayer needles on tree's crown is bigger than that of the lower part needles due to sunlight. On the lower part of tree crown, southern needle's NPR is higher than the northern. However, no difference was presented of NPR of southern and northern needles on the top of the tree crown. Under the conditions of air temperature 20℃, relative humidity 70%±5% and CO2 concentration 305mg·kg-1, the light compensation point of Linzhi spruce is 1075 μmol·m-2·s-1 and its light saturation point is 770 μmol·m-2·s-1. As increasing the light density to 800 μmol·m-2·s-1, the CO2 compensation point is 1572 mg·kg-1 and the CO2 saturation point is 3 81133 mg·kg-1.