摘要
为研究大豆根系在西南山区坡耕地水土保持中的价值,本文在大豆的3个主要生育期(开花期、始粒期和鼓粒期)采集根系和根土复合体样本,采用WinRHIZO(Pro.2019)根系分析系统测定并计算了根系的几何形态特征、分形特征和拓扑结构,用无侧限压缩试验测定了根土复合体的力学特性,分析大豆根系在不同生育期的构型特征及其对土体力学特性的影响。结果表明:1)大豆根系的分形维数在鼓粒期最小,分形丰度在开花期最小,但两者均在始粒期最大;2)拓扑指数随生育期先减小后增大,在始粒期最接近0.5,且平均连接长度最小,根系趋向于叉状分支模式,此时根系分支状态最为复杂;3)大豆根系的分形特征、拓扑特征与根长等主要形态特征参数有极显著相关关系(P<0.01);4)大豆根系能显著增强土体强度,其根土复合体的无侧限抗压强度表现为始粒期(41.44 kPa)>鼓粒期(37.95 kPa)>开花期(29.29 kPa),分形维数和分形丰度与土体的力学特性呈显著正相关关系(P<0.01)。综上,大豆根系分形维数和丰度越大、拓扑指数越小时,根土复合体的无侧限抗压强度越大,其根系固土效应越显著;农作物根系分形特征和拓扑特征不仅可用于表达根系在土体中的分支状态、空间分布和拓展模式,也可作为评价农作物根系固土效应的主要参数。在山区坡耕地的农作物配置中,应注重培育分支复杂、根系发达的大豆品种以防治水土流失。
The sloping farmland area in Yunnan accounts for 70%of the total arable land area,and its sustainability is affected by severe soil erosion.Approximately 89.4%of the sloping farmland in the province is utilized for planting crops,and soybeans are one of the main crops in summer.Previous studies have shown that the soil fixing capacity of vegetation roots plays a significant role in soil and water conservation.This study was conducted to explore the soil-fixing capacity of soybean roots and to provide a basis for the calculation of the soil-fixing ability of crop roots.Thus,a field experiment was designed to have two treatments with three replica-tions for a total of six plots:bare land(CK)and mono-soybean field(SS).Unconfined compression tests were used to determine the shear strength and stress-strain characteristics of rootless soil and root-soil complexes during the three main growth stages of soy-beans(blooming stage,initial grain forming stage,and seed filling stage).The WinRHIZO(Pro.2019)system was employed to ana-lyze the geometric characteristics,fractal characteristics,and topological structure of the roots.The structural characteristics of soy-bean roots at different growth stages and their effects on soil mechanical properties were analyzed.The results indicated that:1)the fractal dimension of soybean roots was the smallest at the seed filling stage,and the fractal abundance was the smallest at the blooming stage,while both were the largest at the initial grain forming stage.2)The topological index of soybean roots was the largest at the seed filling stage,followed by the blooming stage,and was the smallest at the initial grain forming stage,when it was approximately 0.5,with the smallest average link length,suggesting that the soybean roots tended to have a dichotomous topology pattern and reached the most complicated branching status at the initial grain forming stage.3)The fractal characteristics of soybean roots were significantly and positively correlated with the main morphological parameters,such as root length(P<0.01),while the to-pological characteristics were significantly and negatively correlated with them(P<0.01).4)Compared with rootless soil,soybean roots could significantly enhance the strength of root-soil complexes.The unconfined compressive strength of the soybean root-soil complexes was the highest at the initial grain forming stage,followed by the seed filling stage,and was the lowest at the blooming stage,at 41.44 kPa,37.95 kPa,and 29.29 kPa,respectively.The fractal dimension and fractal abundance were significantly and posit-ively correlated with the mechanical properties of the root-soil complexes(P<0.01).In conclusion,the greater the fractal dimension and fractal abundance of soybean roots are,and the smaller the topological index is,the greater the unconfined compressive strength of the root-soil complex is,and the more significant the soil-fixing capacity of soybean roots is.The fractal and topological character-istics of crop roots can not only be used to express the branching status,spatial distribution,and expansion mode of roots in soil,but can also be used as the main parameters to evaluate the soil-fixing capacity of crop roots.This study provides a reference for crop configuration on sloping farmlands in mountainous areas.Soil erosion can be prevented by cultivating soybean varieties with com-plex branches and well-developed roots.
作者
张立芸
段青松
李永梅
ZHANG Liyun;DUAN Qingsong;LI Yongmei(Yunnan Agricultural University,Kunming 650201,China)
出处
《中国生态农业学报（中英文）》
CAS
CSCD
北大核心
2022年第9期1464-1476,共13页
Chinese Journal of Eco-Agriculture
基金
国家自然科学基金项目(41461059)
云南省教育厅科学研究基金项目(2019J0178,2022J0343)资助。
关键词
大豆
坡耕地
根系
分形维数
拓扑指数
水土保持
无侧限抗压强度
Soybean
Sloping farmland
Root system
Fractal dimension
Topological index
Soil and water conservation
Unconfined compressive strength
