土壤养分斑块对比度改变活血丹克隆整合强度和方向

SOIL-NUTRIENT PATCH CONTRAST MODIFIES INTENSITY AND DIRECTION OF CLONAL INTEGRATION IN GLECHOMA LONGITUBA

克隆植物相连片段(或分株)常常生长在不同的土壤养分斑块中。克隆整合使得生长在异质养分斑块中的克隆片段(或分株)产生局部和非局部反应,从而影响相连片段(或分株)的表型可塑性。为了揭示养分斑块对比度对活血丹(Glechomalongituba)克隆整合的影响,在一控制实验中,将活血丹克隆片断种植于4种不同对比度的环境中,即:无对比度(对照)、低对比度、中对比度和高对比度。活血丹在气体交换、水势、荧光、形态、生长与分配方面的克隆整合强度随养分斑块对比度的增强而表现出增强或减弱的变化趋势;养分斑块对比度越强,活血丹气体交换和荧光暗反应的整合强度越小,叶片水势整合强度越大。斑块对比度可改变部分性状的克隆整合方向;超过一定的对比阈值,整合强度随养分对比度的变化趋势会向着相反方向转变。克隆整合对生理特征的修饰幅度小于对生长特征的修饰幅度。这些结果指示:养分斑块对比度可通过修饰克隆整合格局(即强度和方向)而改变克隆植物的表型可塑性。

Aims The connected fragments of clonal plants often grow in different soil-nutrient patches, and clonal integration can modify the plasticity of these connected clonal fragments in diverse ways. We address how nutrient patch contrast modifies intensity and direction of clonal integration. Methods In a common garden experiment, we planted clonal fragments of Glechoma longituba in four nutrient-patch contrast conditions： no （control）, low, medium and high contrast. Water was supplied when necessary. We measured physiological traits at peak growth and harvested all plant materials at the end of the experiment, which ran from July 19 through September 30, 2005. Data were analyzed with SPSS software. Important findings Clonal integration in gas exchange, water potential, fluorescence, growth and biomass allocation differed among nutrient patch contrast treatments. Higher contrast had smaller integration in both gas exchange and dark fluorescence response and greater integration in leaf water potential. Direction of clonal integration for some characteristics also different among treatments, indicating that the threshold of soil-nutrient patch contrast might play a fundamental role in determining integration direction. Clonal integration had far broader effects on growth and allocation than physiological traits. We infer that nutrient-patch contrast may modify the intensity and direction of clonal integration, which in turn can shape the phenotypic plasticity of clonal plants.