根系觅食过程是植物行为的重要组成部分，受到土壤养分浓度、养分分布状况及相邻植物根系竞争等环境因素的显着影响。在根系觅食过程中，植物是否系统集合了这些不同类型的环境信息？它们是如何集成这些信息的？对这些基础性问题的回答，有助于根系生态学研究的深入发展。
根系构型在植物养分吸收过程中扮演重要角色，是衡量其觅食功能的主要指标。木本植物的养分吸收功能主要是由前三级根序完成的，尤其是一级根序（根尖）；传统上依据直径进行根类划分的方法扩大了具有养分吸收能力细根的范围。因此，采用前三级根序构建根系构型指标，将会提高木本植物觅食功能的衡量精度。成都生物所刘庆研究员领导的森林地下生态学科组南宏伟等人通过模拟盆栽试验，基于根序分级理论，探讨了土壤养分状况（均质养分和异质养分）和根系竞争二者共存条件下的亚高山针叶林主要树种云杉幼苗的根系构型。研究发现：竞争区细根单位表面积上的一级根个数（RTRS）在施肥情况下显着升高，而在竞争区和非竞争区均施肥的情况下显着下降，表明植物根系吸收模块（重复的根系单元）的功能实质是对局部环境因素的响应，并受植物整体的调控，从而深入验证了根系觅食行为的模块假说。在均质土壤养分条件下，不论竞争区还是非竞争区，前三级根序长度占总细根长度的百分比均在施肥情况下显着下降。在异质土壤养分条件下，目标植物在非竞争区拥有较高的RTRS或一级根/总细根的长度百分比；在富养斑块中拥有较高的RTRS。不同处理间多样化的觅食行为说明植物集合了土壤养分和竞争状况等环境信息。该研究初步揭示了树木根系觅食行为集合外界信息的内在机制：降低根系竞争强度和增加土壤养分是驱动树木根系吸收模块觅食行为的重要因素。
该研究结果已在线发表于国际著名综合性学术期刊Plos One上（DOI: 10.1371/journal.pone.0065650），该研究得到中国科学院碳专项和科技部支撑项目的资助。（生物谷Bioon.com）
生物谷推荐英文摘要：
PLoS ONE DOI: 10.1371/journal.pone.0065650
Effects of Nutrient Heterogeneity and Competition on Root Architecture of Spruce Seedlings: Implications for an Essential Feature of Root Foraging
Hongwei Nan, Qing Liu mail, Jinsong Chen, Xinying Cheng, Huajun Yin, Chunying Yin, Chunzhang Zhao
Background
We have limited understanding of root foraging responses when plants were simultaneously exposed to nutrient heterogeneity and competition, and our goal was to determine whether and how plants integrate information about nutrients and neighbors in root foraging processes.
Methodology/Principal Findings
The experiment was conducted in split-containers, wherein half of the roots of spruce (Picea asperata) seedlings were subjected to intraspecific root competition (the vegetated half), while the other half experienced no competition (the non-vegetated half). Experimental treatments included fertilization in the vegetated half (FV), the non-vegetated half (FNV), and both compartments (F), as well as no fertilization (NF). The root architecture indicators consisted of the number of root tips over the root surface (RTRS), the length percentage of diameter-based fine root subclasses to total fine root (SRLP), and the length percentage of each root order to total fine root (ROLP). The target plants used novel root foraging behaviors under different combinations of neighboring plant and localized fertilization. In addition, the significant increase in the RTRS of 0–0.2 mm fine roots after fertilization of the vegetated half alone and its significant decrease in fertilizer was applied throughout the plant clearly showed that plant root foraging behavior was regulated by local responses coupled with systemic control mechanisms.
Conclusions/Significance
We measured the root foraging ability for woody plants by means of root architecture indicators constructed by the roots possessing essential nutrient uptake ability (i.e., the first three root orders), and provided new evidence that plants integrate multiple forms of environmental information, such as nutrient status and neighboring competitors, in a non-additive manner during the root foraging process. The interplay between the responses of individual root modules (repetitive root units) to localized environmental signals and the systemic control of these responses may well account for the non-additive features of the root foraging process.
