土壤氮素有效性与克隆整合性对结缕草分枝行为的影响效应

在一个生长季内,对生长于4种生境类型(其中土壤氮素含量呈4种水平)中的克隆植物结缕草的主匍匐茎采取了2种对照处理:保持连接状态和实施节间切断,并检验对其分枝行为产生的生态影响。随着生境内土壤氮素水平的降低,保持连接状态的结缕草植株的分枝强度(按照分枝数量、长度和生物量计测)趋于降低,而实施切断处理的结缕草植株的分枝强度趋于增加。复合节在产生分枝时的根系生物量通常高于未产生分枝时的根系生物量。着生于贫瘠土壤中的根系生物量与着生于肥沃土壤中的根系生物量相比趋于增加。从肥沃土壤斑块中生长出的分枝比从贫瘠土壤斑块中生长出的分枝在数量上占优势。以多个形态学指标衡量,结缕草克隆的A分枝比B分枝具有明显的生长优势。方差分析结果揭示出结缕草克隆的分枝行为对于生境土壤氮素水平以及连接和切断两种处理的响应方式不同。分枝对于结缕草克隆总生物量具有较高的贡献率,而其中A分枝占有较大比例。

Effects of soil nitrogen availability and clonal integration on the branching behaviors of Zoysia japonica

Branching behavior of Zoysia japonica,with and without disconnection at four levels of soil nitrogen content were examined within one growing season.With the decrease of overall soil N levels in the habitats,the branching intensity in terms of number,length and mass tended to decrease,in intact treatments,and increase in disconnection treatments.The average masses of roots at multiple-nodes with branches were usually greater than on those without branches.Root masses at multiple-nodes in the poor soils tended to be greater than corresponding ones in the rich soils.The proportion of branches produced from the rich soil patches were dominant over those from the poor soil patches for all clones.Among whole branches,A-branches were dominant over B-branches in terms of various morphological parameters.The results of ANOVA revealed that the branching behaviors of Z.japonica clones in response to overall soil nitrogen levels and the treatments of intact and disconnection were very different.Branches contributed greatly to the total dry matter production of Z.japonica clones and A-branches constituted a major proportion of this production.