香根草和紫花苜蓿水培根系分泌物缓解黏质红壤机械阻力模拟研究  

Simulation of Lucerne and Vetiver Hydroponic Root Exudates to Alleviate Clayey Red Soil Penetration Resistance

作　　者：何阳波 董俊琦 曾蕙 刘思宇 王法明[2] 杨明萱 郭再华 HE Yangbo;DONG Junqi;ZENG Hui;LIU Siyu;WANG Faming;YANG Mingxuan;GUO Zaihua(Key Laboratory of Arable Land Conservation(Middle and Lower Reaches of Yangtze River),Ministry of Agriculture and Rural Affairs,Huazhong Agriculture University,Wuhan 430070,China;South China Botanical Garden,Chinese Academy of Sciences,Guangzhou 510650,China;School of Life Sciences,Hubei University,Wuhan 430062,China)

机构地区：[1]华中农业大学资源与环境学院/农业部长江中下游耕地保育重点实验室,武汉430070 [2]中国科学院华南植物园,广州510650 [3]湖北大学生命科学学院,武汉430062

出　　处：《土壤学报》2024年第5期1224-1235,共12页Acta Pedologica Sinica

基　　金：国家重点研发计划项目(2021YFC3100402)资助。

摘　　要：南方黏质红壤土壤机械阻力高,本文采用两种植物根系分泌物处理土壤,分析其对两种压实情况下的土壤机械阻力(SPR)影响。通过水培法提取须根系植物香根草和主根系紫花苜蓿根系分泌物,分析其组成特征、并冷冻干燥获取分泌物干物质。分泌物干物质按照4种施加水平处理土壤,之后对平衡后的重塑环刀土壤实施两种压实处理,并分析土壤SPR、含水量(SWC)、团聚体和容重。结果表明:紫花苜蓿根系分泌物中芳香基碳类、烷氧基碳类和羰基碳类相对含量(3.23%、6.83%、55.09%)较香根草高(1.64%、4.12%、45.78%),而疏水物质/亲水物质则呈现相反趋势。SPR随分泌物施加水平升高而降低,但只有施加水平≥0.2 mg·g^(-1)时引起土壤SPR显著降低,且紫花苜蓿降低SPR幅度较香根草明显。相关性和回归分析证明根系分泌物中较低的疏水性物质/亲水性物质比和较高的烷氧基碳类相对含量,通过增加SWC和团聚体平均质量直径降低土壤SPR。综上所述,主根系植物根系分泌物对黏质红壤SPR的缓解效果优于须根系植物。【Objective】The objective of this study was to investigate the influence of fibrous and taproot plant root exudates,in terms of their relative composition and application rate,on soil penetration resistance(SPR)under specific compaction conditions(compaction,and compaction followed by wetting/drying),in order to evaluate the adverse effects of SPR on crop growth in clayey red soil.【Method】Fibrous root vetiver and taproot lucerne were selected to collect hydroponic secretions.These secretions were then analyzed to determine the root exudate composition,which was subsequently freeze-dried to obtain the original dry exudates.Clayey red soils(0~20 cm)were amended with different rates of dry root exudate materials(0,0.02,0.2,and 1 mg·g^(-1),dry root exudates wt/soil wt),and left to equilibrate for one week in a 4℃refrigerator.Soils amended with varying rates of dry root exudates were then compacted into steel cores(d=5 cm and h=5.1 cm)and subjected to two types of compaction.One subset of core samples was wetted to-33 kPa and compacted to 200 kPa stress(compaction),and another subset underwent 200 kPa stress followed by one cycle of saturation and drainage back to-33 kPa(compaction+w/d).The SPR,soil water content(SWC),aggregate properties,and bulk density(Bd)were determined.【Result】The results showed that:(1)The relative content of aromatic carbon,alkoxy carbon,and carbonyl carbon in the root exudates was higher in lucerne(3.23%,6.83%,55.09%)than that in vetiver(1.64%,4.12%,45.78%),whereas the ratio of hydrophobic to hydrophilic substances showed an opposite trend(0.52 for Lucerne and 0.86 for vetiver).(2)The SPR decreased as the exudate rate increased,with a significant decrease observed only when the root exudate application rate exceeded 0.2 mg·g^(-1).For example,compared to the control,0.2 mg·g^(-1) root exudates application from lucerne and vetiver resulted in reductions of 29.4%and 11.4%in SPR,respectively.(3)At the same root exudate application rate,lucerne showed a higher degree of SPR reductio

关 键 词：根系分泌物 土壤机械阻力 黏质红壤 绿肥植物 

分 类 号：S152[农业科学—土壤学]