毛白杨凋落叶对节节麦种子萌发和表型可塑性的影响

Effects of litter leaves of Populus tomentosa Carr.on seed germination and phenotypic plasticity of Aegilops tauschii Coss.

以节节麦(Aegilops tauschii Coss.)种子和幼苗为研究对象,分别用毛白杨(Populus tomentosa Carr.)凋落叶浸提液和毛白杨凋落叶进行处理,探讨毛白杨凋落叶化感防除节节麦的可行性,并分析节节麦在化感逆境中的入侵机制。结果表明:毛白杨凋落叶化感物质对节节麦种子和幼苗均能产生明显的低促高抑化感作用,5 mg·mL^(-1)凋落叶浸提液对种子萌发有促进效应,大于等于40 mg·mL^(-1)时转为抑制效应,使发芽率、发芽势、发芽指数显著(P<0.05)降低,60 mg·mL^(-1)时抑制作用最强;毛白杨凋落叶低添加量(30 g)时,显著促进节节麦各部分构件生物量积累,显著增加总叶面积;施用120 g凋落叶可强烈抑制其生长,使根、茎、叶生物量,以及总叶面积、平均叶面积、叶生物量比、叶根比、相对生长速率显著(P<0.05)降低,证明毛白杨凋落叶对节节麦具备一定的化感作用,具备抑草潜力,高浓度毛白杨凋落叶化感物质显著抑制其种子萌发和植株生长。节节麦作为入侵植物,在适应环境的过程中,根、茎、叶均表现出较强的表型可塑性,尤其是叶片相关指标,总叶面积、叶重、叶生物量比的表型可塑性指数分别为0.81、0.78、0.34。

The aim of this study was to investigate the allelopathic effects of leaf litter extraction and litter decomposition of Populus tomentosa Carr.on seeds and seedings of Aegilops tauschii Coss.Seeds and seedlings of A.tauschi were used as materials in the experiment,and the dish method and pot method were used respectively.The results showed that the regulation of allelopathic substances of P.tomentosa Carr.litters had a concentration effect.The concentration aqueous extract of P.tomentosa Carr.promoted germination at low concentration(5 mg·mL^(-1))and significantly(P<0.05)inhibited it at high concentration(40,60 mg·mL^(-1)).The biomass accumulation and total leaf area were significantly(P<0.05)increased with low leaf litter addition(30 g)of P.tomentosa Carr.to the soil,while in the treatment of high addition(120 g),biomass accumulation,total leaf area,mean leaf area,leaf area ratio,leaf area root mass ratio and relative growth rate were significantly inhibited.The leaves of P.tomentosa Carr.had an allelopathic effect on A.tauschii Coss,high concentrations of allelochemicals in the fallen leaves of P.tomentosa Carr.significantly inhibit seed germination and plant growth of A.tauschii Coss.On the other hand,A.tauschii Coss.showed high phenotypic plasticity in adapting to the environment of fallen leaves of P.tomentosa Carr,leaf had the highest phenotypic plasticity among all plant components,phenotypic plasticity index of total leaf area,leaf biomass,leaf biomass allocation were 0.81,0.78 and 0.34,respectively.