It is important to quantify the effect of the root diameter, the embedment length of the root and load speed on the soil-root interface mechanical properties for studying the root anchorage. The soilroot interface mec...It is important to quantify the effect of the root diameter, the embedment length of the root and load speed on the soil-root interface mechanical properties for studying the root anchorage. The soilroot interface mechanical properties can be obtained through the pullout force and root slippage curve(F-S curve). About 120 Pinus tabulaeformis single roots whose diameters ranged from 1 mm to 10 mm divided into 6 groups based on different root embedment length(50 mm, 100 mm and 150 mm) and different load velocity(10 mm·min^(-1), 50 mm·min^(-1), 100 mm·min^(-1) and 300 mm·min^(-1)) were investigated using the pullout method. This study aims to explore the mechanical properties of the soil-root interface in the real conditions using the pullout test method. The results showed two kinds of pullout test failure modes during the experimental process: breakage failure and pullout failure. The results showed that the roots were easier to be broken when the root diameter was smaller or the loading speed was larger. The relationship between the maximum anchorage force and root diameter was linear and the linearly dependent coefficient(R^2) was larger than 0.85. The anchorage force increased with the root embedment length. An increase of 10%^(-1)5% for the maximumanchorage force was found when load speed increased from 10 to 300 mm.min^(-1). The mean peak slippage of the root was from 13.81 to 35.79 mm when the load velocity varied from 10 to 300 mm.min^(-1). The study will be helpful for the design of slopes reinforced by vegetation and in predicting risk of uprooting of trees, and will have practical benefits for understanding the mechanism of landslide.展开更多
Water movement into and out of roots depends on the water potential difference between the bulk soiland the root xylem and the total hydraulic conductance of the pathway, which can be divided into three parts,i.e. soi...Water movement into and out of roots depends on the water potential difference between the bulk soiland the root xylem and the total hydraulic conductance of the pathway, which can be divided into three parts,i.e. soil conductance, soil-root conductance and root conductance. The vaues and relative importance varywith soil water content. The general rule is that water uptake by roots is mainly limited by radial hydraulicconductance of roots in wet soils, the soil-root interfaCe becomes a major limiting factor to water uptake inmoderately dry soils, and the water uptake is limited by the rapidly decreasing soil hydraulic conductance inseriously dry soils. Meanwhile these limiting factors vary with crop variety, and these variations can be usedto evaluate the drought-resistance and water use efficiency of crops.展开更多
The phosphate in the soil-root interface zone under various soil water contents and application rates ofphosphate was still of depletion distribution which could be described by a power function in the form ofC/Co= ax...The phosphate in the soil-root interface zone under various soil water contents and application rates ofphosphate was still of depletion distribution which could be described by a power function in the form ofC/Co= ax￣b(C/Co is the relative content of fertilized phosphate in a distance from the root surface x, a andb are the regression constants). The depletion rate of phosphate in soil near the root surface was higher andthe depletion range was narrower under lower soil moisture. On the contrary, at higher soil water content thedepletion range was wider, generally The application rate of phosphate led to the greater depletion intensityof phosphorus was higher in the heavier texture soils. In general, the depletion intensity in the soils, whichdecreased with increasing clay content or increa.sing buffering power of soil, decreased in the order as loessalsoil and black fou soil> lou soil> yellow cinnamon soil when 50 or 100 mg of phosphorus were applied in theform of KH_2PO_4. This result indicated that the phosphate distribution and its movement in the soil-rootinterface zone closely related with the buffering capacity of soil.展开更多
【目的】研究不同栽培模式下多花黄精健株和根腐病病株根际土壤细菌群落多样性差异,为土壤微生态调控和多花黄精根腐病的绿色防治提供理论依据。【方法】通过Illumina Mi Seq高通量测序技术对林下和大田栽培的多花黄精健株和根腐病病株...【目的】研究不同栽培模式下多花黄精健株和根腐病病株根际土壤细菌群落多样性差异,为土壤微生态调控和多花黄精根腐病的绿色防治提供理论依据。【方法】通过Illumina Mi Seq高通量测序技术对林下和大田栽培的多花黄精健株和根腐病病株根际土壤细菌群落结构及多样性进行分析,并对土壤细菌群落进行功能预测。【结果】与健株相比,多花黄精病株根际土壤细菌数量下降,但其多样性增加。不同栽培模式下多花黄精健株与病株根际土壤细菌的优势菌门为变形菌门(Proteobacteria)、酸杆菌门(Acidobacteriota)和放线菌门(Actinobacteriota),优势菌属为鞘氨醇单胞菌属(Sphingomonas)和芽单胞菌属(Gemmatimonas)。变形菌门和放线菌门在健株根际土壤中的相对丰度高于病株(大田4年生样品除外),而酸杆菌门相反。鞘氨醇单胞菌属在多花黄精病株根际土壤中的相对丰度高于健株。通过土壤微生物群落功能预测发现,具有新陈代谢功能的土壤细菌群落占比最大,但健株与病株的土壤细菌群落功能无明显差异。【结论】不同栽培模式下多花黄精健株和病株根际土壤细菌群落结构和多样性差异较大,植株根际土壤细菌减少可能是多花黄精患根腐病的重要原因之一。展开更多
基金supported by the Fundamental Research Funds for the Central Universities(No.YX2010-20)the Open Projects Foundation of Key Laboratory of Soil and Water Conservation & Desertification Combat (Beijing ForestryUniversity), Ministry of Education of P.R. China (No.201002) the National Natural Science Foundation of China (No. 31570708, No.30901162)
文摘It is important to quantify the effect of the root diameter, the embedment length of the root and load speed on the soil-root interface mechanical properties for studying the root anchorage. The soilroot interface mechanical properties can be obtained through the pullout force and root slippage curve(F-S curve). About 120 Pinus tabulaeformis single roots whose diameters ranged from 1 mm to 10 mm divided into 6 groups based on different root embedment length(50 mm, 100 mm and 150 mm) and different load velocity(10 mm·min^(-1), 50 mm·min^(-1), 100 mm·min^(-1) and 300 mm·min^(-1)) were investigated using the pullout method. This study aims to explore the mechanical properties of the soil-root interface in the real conditions using the pullout test method. The results showed two kinds of pullout test failure modes during the experimental process: breakage failure and pullout failure. The results showed that the roots were easier to be broken when the root diameter was smaller or the loading speed was larger. The relationship between the maximum anchorage force and root diameter was linear and the linearly dependent coefficient(R^2) was larger than 0.85. The anchorage force increased with the root embedment length. An increase of 10%^(-1)5% for the maximumanchorage force was found when load speed increased from 10 to 300 mm.min^(-1). The mean peak slippage of the root was from 13.81 to 35.79 mm when the load velocity varied from 10 to 300 mm.min^(-1). The study will be helpful for the design of slopes reinforced by vegetation and in predicting risk of uprooting of trees, and will have practical benefits for understanding the mechanism of landslide.
文摘Water movement into and out of roots depends on the water potential difference between the bulk soiland the root xylem and the total hydraulic conductance of the pathway, which can be divided into three parts,i.e. soil conductance, soil-root conductance and root conductance. The vaues and relative importance varywith soil water content. The general rule is that water uptake by roots is mainly limited by radial hydraulicconductance of roots in wet soils, the soil-root interfaCe becomes a major limiting factor to water uptake inmoderately dry soils, and the water uptake is limited by the rapidly decreasing soil hydraulic conductance inseriously dry soils. Meanwhile these limiting factors vary with crop variety, and these variations can be usedto evaluate the drought-resistance and water use efficiency of crops.
文摘The phosphate in the soil-root interface zone under various soil water contents and application rates ofphosphate was still of depletion distribution which could be described by a power function in the form ofC/Co= ax￣b(C/Co is the relative content of fertilized phosphate in a distance from the root surface x, a andb are the regression constants). The depletion rate of phosphate in soil near the root surface was higher andthe depletion range was narrower under lower soil moisture. On the contrary, at higher soil water content thedepletion range was wider, generally The application rate of phosphate led to the greater depletion intensityof phosphorus was higher in the heavier texture soils. In general, the depletion intensity in the soils, whichdecreased with increasing clay content or increa.sing buffering power of soil, decreased in the order as loessalsoil and black fou soil> lou soil> yellow cinnamon soil when 50 or 100 mg of phosphorus were applied in theform of KH_2PO_4. This result indicated that the phosphate distribution and its movement in the soil-rootinterface zone closely related with the buffering capacity of soil.
文摘【目的】研究不同栽培模式下多花黄精健株和根腐病病株根际土壤细菌群落多样性差异,为土壤微生态调控和多花黄精根腐病的绿色防治提供理论依据。【方法】通过Illumina Mi Seq高通量测序技术对林下和大田栽培的多花黄精健株和根腐病病株根际土壤细菌群落结构及多样性进行分析,并对土壤细菌群落进行功能预测。【结果】与健株相比,多花黄精病株根际土壤细菌数量下降,但其多样性增加。不同栽培模式下多花黄精健株与病株根际土壤细菌的优势菌门为变形菌门(Proteobacteria)、酸杆菌门(Acidobacteriota)和放线菌门(Actinobacteriota),优势菌属为鞘氨醇单胞菌属(Sphingomonas)和芽单胞菌属(Gemmatimonas)。变形菌门和放线菌门在健株根际土壤中的相对丰度高于病株(大田4年生样品除外),而酸杆菌门相反。鞘氨醇单胞菌属在多花黄精病株根际土壤中的相对丰度高于健株。通过土壤微生物群落功能预测发现,具有新陈代谢功能的土壤细菌群落占比最大,但健株与病株的土壤细菌群落功能无明显差异。【结论】不同栽培模式下多花黄精健株和病株根际土壤细菌群落结构和多样性差异较大,植株根际土壤细菌减少可能是多花黄精患根腐病的重要原因之一。
