山西太岳山核桃楸光合特性的研究

用Li 6 4 0 0光合作用测定系统对自然生长的核桃楸壮龄林木的光合作用进行测定 .结果如下 :①核桃楸的光合速率在 1d内有两个峰值 ,两个光合峰高度接近 ,上午的光合速率峰持续时间较下午的长 .叶片气孔导度、蒸腾速率与光合速率间表现出较强的正相关 ,日变化曲线呈双峰型 .叶片胞内CO2 浓度受气孔导度和大气CO2 浓度的双重影响 ,呈现出早晚大幅升高 ,正午有 1h的峰值的日变化进程 .②在控制条件下 ,叶片的光合速率在低光合有效辐射 (0～ 5 0μmol (m2 ·s)下 ,表现出随CO2 浓度增加而降低的趋势 ;高出此光合有效辐射值后 ,光合速率随CO2 浓度的增加呈抛物线变化 ,最高点对应的光合有效辐射下的CO2 饱和点 ,且随光合有效辐射的增加CO2 饱和点增高 .当光合有效辐射为0～ 12 0 0 μmol (m2 ·s)时 ,叶片的气孔导度表现出随光合有效辐射的增加而增大 ,随CO2 浓度的增加而减小的趋势 ;光合有效辐射超过 12 0 0 μmol (m2 ·s)后 ,气孔导度随光合有效辐射、CO2 浓度的增加而降低 .叶片蒸腾速率的变化趋势与气孔导度类似 .

Photosynthesis characteristics of Juglans mandshurica Maxim in Taiyue Mountain region, Shanxi Province

By measuring the photosynthesis rate of Juglans mandshurica Maxim under nature and controlled conditions by Li 6400 portable photosynthesis system as well as logging the photosynthesis active radiation (PAR), CO 2 concentration, air temperature,leaf temperature etc. at the same time, it is showed that: ①the diurnal variation of photosynthesis rate is a midday depression pattern,the two peaks have nearly the same height,the peak occurred in morning lasts longer than the afternoon one.The stomatal conductance is strongly related to photosynthesis,and it changes the intercellar CO 2 concentration (Ci) and transpiration rate to some degree. ②Control the PAR at low level (0～50 μmol/(m 2·s),the photosynthesis rate will drop with the increasing of the CO 2 concentration. When the PAR is higher than 50 μmol/(m 2·s), the photosynthesis rate CO 2 concentration curve is a parabola,the peak is the CO 2 concentration saturation point (CSP) and the CSPs increased with the PARs.When the PAR changes between 0 and 1 200μmol/(m 2·s), the stomatal conductance keeps same change trend with PAR and opposite trend with CO 2 concentration.When the PAR is more than 1 200μmol/(m 2·s). the stomatal conductance reduces with the increase of both the PAR and CO 2 concentration. The transpiration rate changes with the stomatal conductance all the time.