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林业科学 ›› 2003, Vol. 39 ›› Issue (3): 23-29.doi: 10.11707/j.1001-7488.20030304

• 论文及研究报告 • 上一篇    下一篇

中亚热带2种原始兰科植物对变化光环境的响应与适应

郭志华 臧润国 奇文清 余让才   

  1. 中国林业科学研究院森林生态环境与保护研究所,北京100091;华南农业大学生物系,广州510632
  • 收稿日期:2001-05-15 修回日期:1900-01-01 出版日期:2003-05-25 发布日期:2003-05-25

THE RESPONSE AND ADAPTATION OF TWO PRIMITIVE ORCHIDS TO A VARIABLE LIGHT ENVIRONMENT IN SUBTROPICAL FORESTS

Guo Zhihua,Zang Runguo,Qi Wenqing,Yu Rangcai   

  1. The Research Institute of Forest Ecology, Environment and Protection, Chinese Academy of Forestry Beijing 100091;Department of Biology, South China Agriculture University Guangzhou 510632
  • Received:2001-05-15 Revised:1900-01-01 Online:2003-05-25 Published:2003-05-25

摘要:

金佛山兰为国家二级保护植物,个体数极少,仅见于南川金佛山及附近的稀疏马尾松林下,并只与其亲缘种金兰生长在一起。在温室内,模拟研究了金佛山兰和金兰对不同强度变化光环境的响应与适应。结果表明:①在强光下利用便携式光合仪长时间观测植物的光合速率时,由于温度的影响,应使用温控系统才能获得更准确结果。②对于PAR 800到200μmol photons·m-2s-1 之间任何强度的光照变化,金佛山兰和金兰的净光合速率、蒸腾速率、胞间CO2 浓度、气孔导度和水分利用率均保持相对稳定,表现出对大幅度变化光环境较好的适应性;对于逐渐遮荫至100 μmol photons·m-2s-1 左右,金佛山兰和金兰均以降低水分利用率、提高光能利用率来适应变化的光环境。③不同强度的间断遮荫对二者光合速率等的影响程度不同。2种原始兰花的净光合速率随间断遮荫均先迅速降至最低,然后逐渐回升,在恢复光照后,金兰比金佛山兰能更快地恢复光合作用;蒸腾速率随间断遮荫迅速降低,恢复光照后,大多能迅速恢复至遮荫前水平。恢复光照后,二者的气孔导度出现不同程度的降低。间断遮荫能导致二者胞间CO2 浓度升高约20%以上,恢复光照后,大多能迅速恢复到原有水平。所有这些,都反映了金佛山兰和金兰对所在地区变化光环境的良好适应性。

关键词: 金佛山兰, 金兰, 光合速率, 蒸腾速率, 变化的光环境

Abstract:

Tangtsinia nanchuanica is a kind of rare and primitive plants, a class Ⅱ protected species in China. Its distribution area is very limited. Together with another primitive orchid, Cephalanthera falcata, they are only found in the understory of subtropical Pinus massoniana forests in Nanchuan, Chongqing, China. Using an open gas-exchange system(LI-COR6400), the response and adaptation of the two orchids to variable sunlight were studied. the results showed that:①Because of the influence of temperature, in order to get more reliable results, the accessory-temperature-control sub-system should be used. ②In any variable light environment from 800 to 200 μmol photons·m-2s-1, the two orchids could keep an almost constant net photosynthetic rate(Pn),transpiration rate (E), stomatal conductivity (Con), water use efficiency (WUE=Pn/E) and internal CO2 concentration (Ci), and manifest the good adaptation to this large light variation. Even shade from 800 to 100 μmol photons·m-2s-1 gradually, their E and C I didn' t change abruptly. In most cases, the water wasn't the limit factor influencing the growth of herbs in the understory of P.massoniana forests, but the light was. So, in order to promote the solar energy use efficiency, the two orchids reduced their WUE to adapt the sun/shade transition. ③In the condition of shade to less than 200 μmol photons·m-2s-1 discontinuously, at the beginning of shade, their Pn declined to the minimum immediately,E and Con also reduced slowly, but the Ci could raise more than 20%. During 5-min shade periods, their Pn rose slowly, their E and Con still reduced slowly, and their Ci could keep the high level. When the light level increased again, C. falcata's Pn would recover more rapidly than T.nanchuanica 's. Their E and Ci could get back to the original levels rapidly in most cases, but the Con couldn't recover. All those above indicated that T.nanchuanica and C.falcata could adapt the variable light environment in the understory of P.massoniana forests very well. Maybe those were the general properties of the shade-tolerant herbs in the subtropical P.massoniana forests.

Key words: Tangtsinia nanchuanica, Cephalanthera falcata, Photosynthesis, Transpiration, Variable sunlight environment