植物光合产物分配受环境因子和生物因子的共同影响。为增进对植物对全球变化响应的理解,从植物个体水平与群落/生态系统水平综述了植物光合产物分配的影响因子与影响机理的最新研究进展。植物个体在光照增强及受水分和养分胁迫时,会将光合产物更多地分配到根系;CO2浓度升高对植物光合产物分配的影响受土壤氮素的制约,植物受氮素胁迫时,CO2浓度升高会促进光合产物更多地分配到根系;反之,对植物光合产物分配没有影响。植物群落/生态系统的光合产物分配对环境因子的响应不敏感;光合产物向根系的分配比例随其生长阶段逐渐降低。功能平衡假说、源汇关系假说和相关生长关系假说分别从环境因子、个体发育和环境因子与个体发育协同作用方面阐述了植物光合产物分配的影响机理。在此基础上,指出了未来拟重点加强的研究方向:1)生态系统尺度的光合产物向呼吸部分的分配研究:2)地下净初级生产力(belowground net primary productivity,BNPP)研究;3)温室和野外条件下及幼苗和成熟林光合产物分配对环境因子响应的比较研究;4)生态系统尺度的多因子控制试验;5)整合环境因子和个体发育对植物光合产物分配格局的影响研究。
Photosynthate allocation is influenced by both environmental and biological factors. This paper reviews recent advances in the mechanism ofphotosynthate allocation and its controls at individual and community/ecosystem levels in order to improve understanding of plant responses to global change. At the individual level, more photosynthate will be allocated to roots under conditions of high light, low water and low nutrient availabilities. The effect of increased atmospheric carbon dioxide concentration on photosynthate allocation depends on soil nitrogen availability. The root mass fraction (RMF) will increase under low nitrogen and is unchanged under high nitrogen. At the community/ecosystem levels, photosynthate allocation is insensitive to environmental change. The RMF decreases with increasing stand age. The functional equilibrium hypothesis (optimal partitioning) can explain the regulation of photosynthate allocation in response to environmental change, the source-sink relationship can reflect the effect of ontogeny on photosynthate allocation and the allometric relationship provides an important theoretical baseline prediction to disentangle the effects of plant size and environmental variation on photosynthate allocation. Research is needed on 1) the fraction of photosynthate allocated to respiration at the ecosystem level, 2) accurate estimation of belowground biomass and belowground net primary productivity (BNPP), 3) comparative study of photosynthate allocations between young and mature forests and between field and greenhouse experiments, 4) effects of multiple factors and their interactions on photosynthate allocation at the ecosystem level and 5) cooperative effects of ontogeny and environmental factors on the regulation of photosynthate allocation.