种群密度对大果虫实形态特征与异速生长的影响

摘要

The aims of this study were to reveal the allometric relationships between population density,plant morphological characteristics,and organ biomass allocation,and to elucidate the adaptive strategy of the plant during the restoration of degraded land.Specifically,we used allometric analysis to evaluate the effect of density on morphological characteristics and the distribution of the biomass of organs in Corispermum macrocarpum.Our results showed that density strongly affects the plant architecture.With an increase in density,the height of C.macrocarpum decreased,and the branch number and length clearly decreased.The biomass of all organs decreased significantly with an increase in density.With an increase in the population density,the biomass allocation was decreased to stem and reproductive organs,but increased to the root and leaf organs.These findings are consistent with the prediction of optimal allocation theory in the context of moisture,nutrient,and light limitation.The allometric relationship of height vs.root biomass was significantly influenced by density.Changes of root vs.above-ground biomass,leaf vs.root,and reproductive organs vs.root were not related to population density,indicating a state of ' apparent plasticity.' The allometric relationships of root vs.stem,stem vs.above-ground biomass,leaf vs.other organs,and reproductive organs vs.other organs were significantly affected by population density,showing a state of ' true plasticity.' Our results suggest that population density changes the ontogenesis system of plant architecture in C.macrocarpum,and can indeed affect the allometric relationships of organs,resulting in a trade-off in biomass allocation among organs to complete the life history.%为揭示种群密度与植物形态特征、器官生物量间的异速生长关系,阐明植物在退化土地恢复过程中的适应策略,以大果虫实为材料,通过异速生长分析方法,研究种群密度对其形态特征、生物量分配与异速生长的影响.结果表明,种群密度对大果虫实的株型构建产生了显著地影响.随着密度增大,大果虫实株高呈减小趋势,其分枝数及分枝长度明显减小.大果虫实各器官生物量随密度增大而显著减小.随密度增大,茎和繁殖器官生物量分配呈减小趋势,根和叶片生物量分配呈增大趋势.这与最优化分配理论中水分、营养物质及光资源受限时的情况一致.密度对大果虫实株高:根生物量间异速生长具有显著影响,且对株高与器官生物量间异速指数和个体大小产生了极显著影响.密度对根:地上部分、叶片:根、繁殖器官:根生物量间的影响属于表观可塑性,而对根:茎、茎:地上部分、叶:其他器官及繁殖器官:其他器官生物量间的影响属于真正可塑性,说明密度改变了大果虫实的株型发育系统,并影响各器官间的异速生长,进而权衡器官生物量分配以完成生活史.