摘要
种植密度和氮供应量可以影响植物的生存和养分利用策略,但这两个因子对植物生长和元素平衡的交互影响目前仍不清楚。本研究以拟南芥(Arabidopsis thaliana)为研究对象开展控制实验,设置4个种植密度和4个氮添加水平的组合处理,探究了植物生物量产量(用总生物量和生物量分配来表征)和养分利用策略(用叶片氮磷计量来表征)的相应变化。研究结果表明,生物量-密度关系受到氮供应量的调控,在低氮水平下呈负相关关系,而在高氮水平下呈现近似最终产量恒定的趋势。过量的氮添加在低密度下抑制植物生长,而这种负影响随着种植密度的增加而逐渐得到缓解。根冠比在低氮水平下随种植密度的增加而增加,但在高氮水平下随种植密度的增加而降低。相比种植密度,氮供应量对叶片氮磷计量特征存在更重要的调控作用:随着氮添加水平的增加,叶片氮含量(或磷含量)呈现增加(或降低)的趋势,导致这两种元素浓度间存在负相关幂律关系。总之,这些研究结果表明,氮供应量和种植密度对拟南芥的生物量产量和叶片化学计量特征存在交互作用。因此,今后预测植物在养分变化下的种间竞争时需要考虑这两个因子间的交互作用。
Plant density and nitrogen(N)availability influence plant survival and nutrient use strategies,but the interaction between these two factors for plant growth and the balance of elements remains poorly addressed.Here,we conducted experimental manipulations using Arabidopsis thaliana,with the combination of four levels of plant density and four levels of N addition,and then examined the corresponding changes in plant biomass production(indicated by total plant biomass and biomass partitioning)and nutrient use strategies(indicated by leaf N and phosphorus(P)stoichiometry).The biomass-density relationship was regulated by N availability,with a negative pattern in low N availability but an asymptotic constant final yield pattern at high N availability.Excessive N addition reduced plant growth at low plant density,but this effect was alleviated by increasing plant density.The root to shoot biomass ratio increased with plant density at low N availability,but decreased at high N availability.N availability was more important than plant density in regulating leaf N and P stoichiometry,with the increasing leaf N concentration and decreasing leaf P concentration under increasing N addition,resulting in a negative scaling relationship between these two elemental concentrations.Our results show that N availability and plant density interactively regulate plant biomass production and leaf stoichiometry of A.thaliana,and highlight that the interactive effects of these two factors should be considered when predicting plant growth behaviour under intraspecific competitive environments in the context of nutrient changes.
基金
supported by the National Natural Science Foundation of China(project nos.31901086,31988102,31800397)
the National Key Research and Development Program of China(2017YFC0503906).
