根系覓食過程是植物行為的重要組成部分,，受到土壤養(yǎng)分濃度、養(yǎng)分分布狀況及相鄰植物根系競(jìng)爭(zhēng)等環(huán)境因素的顯著影響,。在根系覓食過程中,，植物是否系統(tǒng)集合了這些不同類型的環(huán)境信息？它們是如何集成這些信息的,？對(duì)這些基礎(chǔ)性問題的回答,，有助于根系生態(tài)學(xué)研究的深入發(fā)展。
根系構(gòu)型在植物養(yǎng)分吸收過程中扮演重要角色,，是衡量其覓食功能的主要指標(biāo),。木本植物的養(yǎng)分吸收功能主要是由前三級(jí)根序完成的，尤其是一級(jí)根序（根尖）,；傳統(tǒng)上依據(jù)直徑進(jìn)行根類劃分的方法擴(kuò)大了具有養(yǎng)分吸收能力細(xì)根的范圍,。因此，采用前三級(jí)根序構(gòu)建根系構(gòu)型指標(biāo),，將會(huì)提高木本植物覓食功能的衡量精度,。成都生物所劉慶研究員領(lǐng)導(dǎo)的森林地下生態(tài)學(xué)科組南宏偉等人通過模擬盆栽試驗(yàn)，基于根序分級(jí)理論,，探討了土壤養(yǎng)分狀況（均質(zhì)養(yǎng)分和異質(zhì)養(yǎng)分）和根系競(jìng)爭(zhēng)二者共存條件下的亞高山針葉林主要樹種云杉幼苗的根系構(gòu)型,。研究發(fā)現(xiàn)：競(jìng)爭(zhēng)區(qū)細(xì)根單位表面積上的一級(jí)根個(gè)數(shù)（RTRS）在施肥情況下顯著升高，而在競(jìng)爭(zhēng)區(qū)和非競(jìng)爭(zhēng)區(qū)均施肥的情況下顯著下降,，表明植物根系吸收模塊（重復(fù)的根系單元）的功能實(shí)質(zhì)是對(duì)局部環(huán)境因素的響應(yīng)，并受植物整體的調(diào)控,，從而深入驗(yàn)證了根系覓食行為的模塊假說,。在均質(zhì)土壤養(yǎng)分條件下，不論競(jìng)爭(zhēng)區(qū)還是非競(jìng)爭(zhēng)區(qū),，前三級(jí)根序長(zhǎng)度占總細(xì)根長(zhǎng)度的百分比均在施肥情況下顯著下降,。在異質(zhì)土壤養(yǎng)分條件下，目標(biāo)植物在非競(jìng)爭(zhēng)區(qū)擁有較高的RTRS或一級(jí)根/總細(xì)根的長(zhǎng)度百分比,；在富養(yǎng)斑塊中擁有較高的RTRS,。不同處理間多樣化的覓食行為說明植物集合了土壤養(yǎng)分和競(jìng)爭(zhēng)狀況等環(huán)境信息。該研究初步揭示了樹木根系覓食行為集合外界信息的內(nèi)在機(jī)制：降低根系競(jìng)爭(zhēng)強(qiáng)度和增加土壤養(yǎng)分是驅(qū)動(dòng)樹木根系吸收模塊覓食行為的重要因素。
該研究結(jié)果已在線發(fā)表于國際著名綜合性學(xué)術(shù)期刊Plos One上（DOI: 10.1371/journal.pone.0065650）,，該研究得到中國科學(xué)院碳專項(xiàng)和科技部支撐項(xiàng)目的資助,。（生物谷Bioon.com）
生物谷推薦英文摘要：
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.
