桉树等速生树种光合速率测定分析

在晴天适宜条件下,对邓恩桉Eucalyptus dunnii Maid、樟树Cinnamomum camphora、洋玉兰Magnolia grandiflora等速生树种采用LI-6400 p便携式光合测定系统测定其叶片的光合速率、蒸腾速率、气孔导度、胞间CO2浓度等的日变化.结果表明:邓恩桉、樟树和洋玉兰三者的光合作用日变化均呈双峰型,都存在光合午休现象,邓恩桉与樟树的光合速率高于洋玉兰,且邓恩桉和樟树能充分的利用午后丰富的光热资源,光合午休持续的时间比洋玉兰短.邓恩桉、樟树与洋玉兰3个树种的蒸腾速率日变化基本相似,均呈双峰型,但邓恩桉的蒸腾速率比樟树和洋玉兰的蒸腾速率大.3个树种的蒸腾速率与光合速率间均存在相同的变化趋势.蒸腾速率在很大程度上决定于气孔导度,3个树种的气孔导度与各自的光合速率日变化趋势都有很强的正相关关系.

Measurement and Analysis of the Photosynthesis Velocity of Fast Growing Species Such as Eucalyptus

Under the proper condition of sunny days, LI-6400 Portable Photosyntyesis System is used to study the characteristics and the diurnal changes of fast growing species of Eucalyptus dunnii Maid and Cinnamomum camphora in the natural conditions such as photosynthetic rate (P_n), transpiration rate (T_r), stomatal conductance (Cond), CO_2 concentration between the cells. Meanwhile, it is compared with the slowly growing tree Magnolia grandiflora. The results show that: (1) The diurnal changes curves of photosynthetic rate of Eucalyptus dunnii Maid, Cinnamomum camphora, Magnolia grandiflora are all taken on a double peak curve, and all has "noon break". The former two are higher than the last one. (2) The diurnal changes curves of transpiration rate of all the three species are similar, and similar to their photosynthetic rate curves, and are all taken on a double peak curve. The former is higher than the last two. (3) The stomata conductance of the three species is positively correlated with the photosynthetic rate, and it is largely decided by the transpiration rate. (4) CO_2 concentration between the cells of three species is affected by the CO_2 concentration in the air and stomatal conductance. (5) The vapor pressure deficit is attributed to the photosynthesis active radiation and the leaf temperature.