采用盆栽法，通过非遮光（全光照）和遮光（光照强度约为全光照的20％）以及控制土壤含水量（高、中、低含水量分别为田间最大持水量的75％～80％、55％～60％和45％～50％），研究了不同光照条件和土壤含水量对节节麦（Aegilops tauschii Coss.）幼苗表型可塑性的影响；并采用生物测定法，比较了各处理组节节麦处理液的化感作用差异。结果表明：光照及土壤含水量的降低均可导致节节麦幼苗单株总干质量的降低，且遮光处理组幼苗根、茎和叶的干质量比以及根冠比、叶面积比、叶根比和比叶面积总体上高于非遮光处理组。其中，遮光-低含水量处理组幼苗单株总干质量最低，叶干质量比、叶面积比和叶根比最大；遮光-高含水量处理组幼苗根干质量比最大；遮光-中含水量处理组幼苗茎干质量比和比叶面积最大。各处理组间幼苗单株总干质量和各器官干质量比以及各形态指标的表型可塑性指数差异明显，以叶根比的表型可塑性指数最大（0.96），茎干质量比的表型可塑性指数最小（0.42）。生物测定结果表明：随各处理组节节麦处理液浓度（0、10、25和50 mg·mL^-1）的升高，小白菜（Brassica rapa Linn.）种子发芽率呈逐渐下降的趋势，且在相同光照条件下，随土壤含水量降低种子发芽率升高；总体上，非遮光处理组的种子发芽率均低于遮光处理组。从化感效应指数（RI）看，总体上除了非遮光-高含水量和非遮光-中含水量处理组小白菜幼苗苗高的RI值为正值外，各处理组小白菜幼苗苗高、主根长和单株鲜质量的RI值均为负值。从综合化感效应（SE）看，各处理组的SE值均为负值，且在节节麦处理液浓度相同条件下，相同光照处理组的SE值整体上随土壤含水量的降低而逐渐减小，相同土壤含水量处理组的SE值整体上也随光照的降低而逐渐减小；总体上，遮光处理组的SE值的绝对值大于非遮光处理组。综合分析结果表明：光照对节节麦生长和化感效应的影响作用较土壤含水量更大。在光照和水分胁迫条件下，节节麦幼苗减少了自身对化感物质的投入，并表现出较高的表型可塑性，且主要通过调节与叶片形态相关的指标适应生境条件变化。

Effects of different light conditions and soil water contents on phenotypic plasticity of Aegilops tauschii Coss. seedlings were studied by no shading （full light） and shading （light intensity of 20％ of full light）， and controlling soil water content （high， moderate and low water contents of 75％-80％， 55％-60％ and 45％-50％ of the maximum water holding capacity in field， respectively） with potculture method； difference in allelopathic effect of treatment solution from A. tauschii in each treatment group was compared by using bioassay method. The results show that decreases of light and soil water content both can cause decrease of total dry mass per plant of A. tauschii seedlings， and dry mass ratios of root， stem and leaf， and root／shoot ratio， leaf area ratio， leaf／root ratio and specific leaf area of seedlings in shading treatment groups are generally higher than those in no shading treatment groups. In which， total dry mass per plant of seedlings in shadinglow water content treatment group is the lowest， and leaf dry mass ratio， leaf area ratio and leaf／root ratio are the largest； root dry mass ratio of seedlings in shadinghigh water content treatment group is the largest; stem dry mass ratio and specific leaf area of seedlings in shadingmoderate water content treatment group are both the largest. There are obvious differences in phenotypic plasticity indexes of total dry mass per plant， dry mass ratio of each organ and each morphology index of seedlings among each treatment group， and phenotypic plasticity index of leaf／root ratio is the largest （0.96）， while that of dry mass ratio of stem is the smallest （0.42）. The bioassay result shows that with the increase of concentration （0， 10， 25， and 50 mg·mL^-1） of treatment solution from A. tauschii in each treatment group， seed germination rate of Brassica rapa Linn. decreases gradually， and seed germination rate increases with the decrease of soil water content under the same light condition； in general， seed germination rates in no shading treatment groups are all lower than those in shading treatment groups. From the view of allelopathic effect index （RI）， except RI values of seedling height of B. rapa seedlings in no shadinghigh water content and no shadingmoderate water content treatment groups are positive， while those of seedling height， main root length， and fresh mass per plant of B. rapa seedlings in each treatment group are all negative in general. From the view of synthetical allelopathic effect （SE）， SE values in each treatment group are all negative， and SE values in the same light treatment group gradually decrease with decrease of soil water content， those in the same soil water content treatment group also gradually decrease with decrease of light under the same concentration of treatment solution from A. tauschii； in general， absolute values of SE values in shading treatment groups are larger than those in no shading treatment groups. The comprehensive analysis result shows that light has more effect on growth and allelopathic effect of A. tauschii than that of soil water content. Under light and water stress conditions， A. tauschii seedlings decrease their contribution to allelochemicals， show relatively high phenotypic plasticity， and adapt to the change of habitat condition by regulating indexes related to leaf morphology.