杉木苗木光合作用及其产物分配对水分胁迫的响应  

EFFECTS OF WATER STRESS ON PHOTOSYNTHESIS AND CARBON ALLOCATION IN CUNNINGHAMIA LANCEOLATA SEEDLING

作　　者：韦莉莉[1] 张小全[1] 侯振宏[1] 徐德应[1] 余雪标[2] 

机构地区：[1]中国林业科学研究院森林生态环境研究所,北京100091 [2]华南热带农业大学,海南儋洲571737

出　　处：《植物生态学报》2005年第3期394-402,共9页Chinese Journal of Plant Ecology

基　　金：国家自然科学基金项目"杉木人工林光合产物分配研究"(3 0 170 762 );国家林业局森林生态环境重点实验室资助项目

摘　　要：使用LI_6 4 0 0红外CO2 气体分析仪并应用13 C稳定性同位素脉冲标记方法,研究了两年生杉木(Cunning hamialanceolata)苗木在水分胁迫下的光合特性及光合产物的分配规律和分配格局的变化。干旱处理没有明显抑制苗木在饱和光强以下的净光合速率。干旱处理各器官13 C自然丰度略高于正常的对照处理。从标记后1～2 1d苗木光合产物分配的动态过程来看,干旱处理全株稳定性碳同位素比值(δ13 C值)和单位质量碳的净增加比率(N13 CR)的平均值均低于对照,即水分胁迫限制了苗木对13 C的吸收,而且对地上部分的影响大于地下部分。生长季结束时对苗木干重的测定结果表明,水分胁迫对苗木地上部分生物量影响较大,而对地下部分生物量的影响不明显。在苗木各器官中,水分胁迫对当年生针叶的影响最大。水分亏缺条件下当年生针叶的δ13 C值、N13 CR和生物量均明显低于对照,标记后2 1d内其N13 CR降幅最大,表明水分胁迫使苗木当年生针叶的碳输出增加。当年生针叶生长的降低使苗木光合总面积减少,因而净初级生产的总量减少。另外,水分胁迫下苗木全株的平均N13 CR降幅大于对照,即13 C的流失增加。水分胁迫下光合产物向地下部分尤其是细根迁移,使地下部分的分配比例增加,最终改变了苗木光合产物的分配格局,使根冠比增加。Changing the allocation of carbohydrates to various organs is a central mechanism by which plants cope with temporally or spatially varying environments. Hence, a primary objective of eco-physiological research is to understand when and how this process is affected by specific external conditions. Chinese fir (Cunninghamia lanceolata) is one of the most important timber species in Southern China due to its fast growth and good timber quality. Due to large-scale afforestation/reforestation activities, Chinese fir stands, most of which are plantations, have expanded rapidly since the 1950s, and, in particular, since the 1980s, with both the area and standing volume having more than doubled. Therefore, to understand the carbon allocation in Chinese fir in response to varying soil moisture conditions, we studied the photosynthetic response and changes in photosynthate allocation of 2-year-old Chinese fir seedlings under different water treatments. The experiment was conducted in the Subtropical Forestry Experimental Center of the Chinese Academy of Forestry located in Fengyi of Jiangxi Province. Eighty potted 2-year-old Chinese fir seedlings were grown for one growing season under two water treatments: a water stress treatment in which one third the normal water supply was applied and a control (normal water management). The net photosynthetic rate (P n) in response to photosynthetic photo flux density (PPFD) were measured using a LI-6400 portable photosynthesis system from 8∶00 to 11∶00 on clear days in late June. Air temperature and relative humidity in the chamber were maintained at (25±1) ℃ and 70%±5%. Carbon allocation in seedlings under the two water treatments was measured in the morning of early July using a 13 C pulse labeling technique. The initial CO 2 concentration in the labeling chamber was about 1 000 μmol·mol -1 and each labeling lasted 40 minutes. The current-needles, 1-year old needles, branches, stems, fine roots and coarse roots were sampled on day 1, day 3, day 7 and day

关 键 词：杉木 苗木 光合作用 光合产物分配 水分胁迫 根冠比 

分 类 号：S791.27[农业科学—林木遗传育种]