Abstract:

To study growth responses of the roots of Panicum miliaceum L. to heterogeneous supply of nutrients. The authors analyzed the effects of the nutrient levels in both original patches (O) and destination patches (D) on the root growth of P. miliaceum when its roots were allowed to extend from original patch into destination patch. When the nutrient levels in the original patches were low, coarse root biomass ratio (coarse root biomass in the D/total coarse root biomass), coarse root length ratio (coarse root length in the D/total coarse root length), coarse root surface area ratio (coarse root surface area in the D/total coarse root surface area) and fine root length ratio (fine root length in the D/total fine root length) were greater in the destination patches with lower nutrient levels than in the destination patches with higher nutrient levels, while fine root length, fine root length density, fine root surface index, and fine root surface area density were smaller in the former than in the latter. When the nutrient levels in the original patches were high, fine root length, fine root length density, fine root surface area index and fine root surface density were greater in the destination patches with lower nutrient levels than in the destination patches with higher nutrient levels, coarse roots did not respond to the nutrient levels in the destination patches significantly. When the roots extended from the original patches with the same nutrient level into the destination patches with contrasting nutrient levels, fine root biomass and its percentage allocation did not respond to the nutrient levels in the destination patches significantly, whereas both root length and root surface area did. This indicates that the fine roots of P. miliaceum responded to difference in nutrient supply by plasticity in their length and surface area, rather than in their root biomass.

异质养分环境中一年生分蘖草本黍根系的生长特征
何维明^1,2 董鸣^1*

（1. 中国科学院植物研究所植被数量生态学开放研究实验室，北京100093
2.  北京师范大学资源科学研究所；环境演变与自然灾害教育部重点实验室，北京100875）

摘要：为揭示黍(Panicum miliaceum L.)根系对异质养分环境的生长反应,作者研究了黍根系从起始斑块向目标斑块水平生长时,起始斑块和目标斑块养分水平对根生长的影响.就低养分起始斑块而言,粗根生物量、粗根长度、粗根表面积和细根长度在高养分目标斑块中的分配比例均小于其在低养分目标斑块中的分配比例,而细根长度及其密度、细根表面积指数及其密度的变化恰好相反.就高养分起始斑块而言,高养分目标斑块的细根长度、细根长度密度、细根表面积指数和细根表面积密度均小于低养分目标斑块,而粗根对目标斑块中养分状况的反应不明显.当黍根系从相同的起始斑块进入不同的目标斑块后,目标斑块的养分状况对细根生物量及其分配无影响,而显著影响细根长度和表面积.这指示细根是通过长度和表面积可塑性而不是生物量变化响应目标斑块中的养分差异.

关键词： 黍；养分斑块；根生物量；根长度；根表面积；根密度

Key words: Panicum miliaceum , nutrient patch, root biomass, root length, root surface area, root density