密度制约决定的植物生物量分配格局

Density dependence-determined plant biomass allocation pattern

基于自然环境下红葱(Allium cepa var.proliferum)个体各器官生物量积累动态、生物量分配比例动态、生物量比率动态和形态性状对不同种群密度(36、49、64、121和225株·m-2)响应的模拟实验,分析了密度制约对其生物量分配格局的影响。结果表明:红葱地上部分、叶和鞘的生物量分配比例均随密度的增加而增加,地下部分和鳞茎的分配比例随密度的增加而下降,而根的分配比例未随密度发生显著变化。除根:叶、根:地上比在密度处理间无显著差异外,各器官间生物量比率均表现出明显的密度依赖性。随着个体的生长,根:鞘、根:叶、根:地上比逐渐减小,鳞茎:叶、鳞茎:鞘、鳞茎:地上比先减小后增加,而地上:地下比先增加后减小。比叶面积与密度呈显著正相关(P<0.01),叶面积和根长与密度呈显著负相关(P<0.05),而比根长不受密度的影响。由此可见,种内竞争水平会对植物体内的资源分配产生较大影响;植物生物量分配格局响应不同密度具有可塑性,随着密度的增加,红葱个体会增加地上营养器官的生物量分配,并以减小地下无性繁殖器官的生物量分配为代价。最优化分配理论仅在无竞争存在的情况下适用,当竞争发生时,种群密度及其制约性调节是决定植物生物量分配格局的关键因素。

A simulation experiment under natural condition was conducted to study the dynamics of biomass accumulation,biomass allocation percentage,biomass ratio,and morphological traits of Allium cepa var.proliferum at different plant densities（36,49,64,121 allocatione to and 225 individuals·m-2）,aimed to analyze the effects of density-dependence on the biomass allocation pattern of A.cepa var.proliferum.With increasing plant density,the biomass allocation to above-ground part,leaf,and sheath increased,but less to below-ground part and bulb,while the blomass allocation to root biomass remained constant.The biomass ratios of above-to belowground parts,sheath to leaf,root to sheath,bulb to root,bulb to leaf,bulb to sheath,and bulb to shoot exhibited apparent density-dependence,but the ratios of root to leaf and root to shoot remained unchanged.With the growth of plant,the ratios of sheath to leaf and bulb to root increased gradually,ratios of root to sheath,root to leaf,and root to shoot were in reverse,ratios of bulb to leaf,bulb to sheath,and bulb to shoot increased after an initial decrease,and the ratio of above-to below-ground parts decreased after an initial increase.Plant density had significant negative effects on specific leaf area（P0.001）,positive effects on leaf area and root length（P 0.05）,but less effects on specific root length（P0.05）.All the results suggested that intraspecific competition exerted great influence on the resource allocation inside plant bodies.In response to different plant densities,the biomass allocation patterns displayed plasticity.With the increase of plant density,the photosynthates allocated more to above-ground vegetative organs,with the cost of decreasing the photosynthates allocation to below-ground asexsual reproductive organ.It was appeared that the＂optimal partitioning theory＂was only applicable at the absence of plant competition between individual plants.When the competition between plants was present,the population density and density-dependent regulation were the important factors determining plant biomass allocation pattern.