摘要
细根空间分布特征能够反映植物对环境的利用程度和适应性,这对评价植物适应逆境至关重要。为了探究胡杨细根空间分布在干旱环境下的适应性特征,以塔里木河下游极端干旱区不同地下水埋深条件下的成年胡杨(Populus euphratica Oliv.)为对象,采用人工挖掘法,对胡杨细根(D≤2 mm)空间分布及其与地下水埋深和土壤水分的关系进行了研究。结果显示:(1)在水平方向上(550 cm范围内),胡杨细根的根长密度(RLD)、表面积密度(SAD)、根质量密度(RMD)随水平距离的增加未发生显著变化;(2)在垂直方向上,土壤表层基本无细根分布,随土壤深度加深,胡杨细根RLD、RMD呈先增加后减少的分布特征,并且在地下水埋深较深处,胡杨细根在较深土壤层(280 cm)仍保持较高的比根长(SRL)和比表面积(SRA);(3)胡杨细根RLD、RMD与上层土壤(0~180 cm)含水量存在较高的正相关关系,而与深层土壤(180 cm以下)含水量存在空间差异。本研究表明生长在上层土壤(0~180 cm)的胡杨细根主要受水分的限制,而生长在土壤深层的细根很可能受地下水埋深的影响,同时为了应对干旱环境,胡杨根系不仅具有较强的水平扩展能力,也会向深层湿润的土壤发展。研究结果可为极端干旱环境下胡杨适应机制的研究提供参考。
The spatial distribution of fine roots can well reflect the utilization degree and adaptability of plants to the environment,which is essential for the evaluation of adaptation to adverse circumstances. We investigated the spatial distribution of Populus euphratica Oliv. fine roots( D ≤ 2 mm) and the relationship with groundwater depth and soil water content. Fine roots and soil samples were collected by the artificial trench profile method. Results showed that:( 1) In the horizontal direction( range of 550 cm),fine root length density( RLD),fine root surface area density( SAD),and fine root mass density( RMD) of P. euphratica changed insignificantly with distance from the tree trunk.( 2) In the vertical direction,there were almost no fine roots in the top layer of the soil profile. With the increase in soil depth,both RLD and RMD exhibited increasing trends at first,and then showed decreasing trends. We found highfine specific root length( SRL) and specific root area( SRA) of P. euphratica at the 280 cm soil depth.( 3) RLD and RMD showed positive correlations with soil moisture content of the upper soil( 0-180 cm),but exhibited spatial heterogeneities with soil moisture at deeper layers. These results revealed that P. euphratica roots were restricted by soil water conditions in the upper soil,and the fine roots in deeper soil were mainly affected by groundwater. The P.euphratica root system not only demonstrated the ability to develop into the deep moist soil,but also showed a strong horizontal expansion capability to cope with drought environments.This study provides a reference for understanding the adaptation mechanism of P. euphratica to extremely arid environments.
出处
《植物科学学报》
CAS
CSCD
北大核心
2018年第1期45-53,共9页
Plant Science Journal
基金
中国科学院STS计划项目(TSS-2015-014-FW-2-3)
国家自然科学基金项目(41371515)
关键词
极端干旱区
胡杨
细根分布
土壤含水量
地下水埋深
Extremely arid region
Populus euphratica~ Distribution of fine roots
Soil water content
Groundwater depth