异质光环境下克隆整合对白夹竹光合氮分配格局的影响

采用盆栽试验,以单轴散生型竹类植物——白夹竹(Phyllostachys bissetii)克隆片段为对象,使近端分株处于自然光照环境,远端分株处于遮荫环境中,对根状茎作切断或不切断处理,研究克隆整合对远端分株和近端分株光合氮分配格局的影响。结果表明:(1)根状茎保持连接的远端分株较根状茎切断的远端分株具有更高的最大净光合速率、叶片氮含量、光合色素含量、叶片光合氮分配系数。(2)相对根状茎切断处理,根状茎保持连接的远端分株将更多的氮分配到光合系统的羧化系统、生物力能学组分,而分配至捕光系统组分的比例较小。(3)比较处于自然光照条件的近端分株,比叶重、叶片氮含量等并没有因根状茎切断与否表现出显著性差异,根状茎连接的近端分株部分指标甚至高于根状茎切断的近端分株。研究认为,克隆整合作用影响处于遮荫环境的白夹竹远端分株的光合氮分配格局,使得处于遮荫生境中的克隆分株依旧维持较高的光合能力,保证了处于逆境条件下克隆分株的生存与生长。

Effects of clonal integration on patterns of nitrogen allocated to photosystem in Phyllostachys bissetii under heterogeneity light environment

In this study, a pot experiment was conducted and clonal fragment of Phyllostachys bissetii with two successive ramets was used as experimental materials to examine the effects of clonal integration on the patterns of nitrogen, allocated to photosystem in P. bissetii under heterogeneity light environment. The main results were as follows:(1)When grown in shade, ramets connected with an unshaded mother plant displayed higher potential maximum net photosynthetic rate(P_max), leaf nitrogen content(N_M and N_A), chlorophyll content and total partition coefficients of leaf nitrogen in photosynthetic apparatus(P_T)than severed ramets.(2)The connected apical ramets had higher partition coefficients of leaf nitrogen in carboxylation components and bioenergetics components than that of in light-harvesting components.(3)There were no significant differences in unit-area leaf mass and nitrogen content between the two treatments of connected and severed proximal ramets in natural lighting conditions, while connected ramets displayed higher P_max, P_T and chlorophyll concentration. The results suggested that clonal integration affects the patterns of nitrogen allocated to photosystem in shaded apical ramets, and ensure young ramets maintain higher photosynthetic capacity, which impel the whole clone fragment had higher survival advantages.