Evaluation of the root-border-cells function in rhizosphere to decrease soil mechanical impedance.

评估根际根际细胞降低土壤机械阻抗的功能。

• 批准号: 12460010
• 负责人: IIJIMA Mario
• 金额: $ 6.53万
• 依托单位: Nagoya University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B)
• 财政年份: 2000
• 资助国家: 日本
• 起止时间: 2000 至 2002
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-12460010/
• 关键词: cell production rates; cell release; decapping; mucilage exudation; root cap; root border cell; soil compaction; soil mechanical impedance; トウモロコシ; ストレス耐性

Plant roots grown in compacted soils have to overcome the mechanical impedance of the soil to root elongation. The friction between soil and the growing root may be decreased by the layer of root border cells. We tried to evaluate the role of the root border cells to decreasing the soil mechanical impedance. In the series of experiment, we found the following:1. For the first time, we quantified the rate of sloughing of root border cells in an abrasive growth medium. The number of maize root border cells increased as a result of compaction, from 1930 to 3220 d^<-1> per primary root. The whole of the cap surface area was covered with detached cells in compacted sand, compared with about 7% of the surface area in loose sand. 2. We developed an image analysis procedure to quantify cell locations in the median longitudinal section of root caps. Only 7% of cells in the outermost layer of the root were associated with the columella region of the cap. 3. Mechanical impedance slightly enhanced meristematic activities in the lateral region of the root cap. Cell production rates were 2,010 cells d^<-1> in compact and 1,570 cells d^<-1> in loose. 4. The presence of a root cap alleviates much of the mechanical impedance to root penetration, and enables roots to grow faster in compacted soils. 5. The contribution of root border cells to the reduction in soil resistance by the presence of root cap was 58%. 6. A technique was developed to separate root border cells from soil particles. The number of root border cells in wet soil was significantly greater than that in the dry soil.In conclusion, the lubricating layer of root border cells decreases frictional resistance to soil penetration.

生长在压实土壤中的植物根系必须克服土壤对根伸长的机械阻抗。根缘细胞层的存在可以减小土壤与生长根系之间的摩擦力。探讨了根系边缘细胞在降低土壤机械阻抗中的作用。在一系列的实验中，我们发现：1.我们第一次量化了根边缘细胞在研磨生长培养基中脱落的速率。玉米根边缘细胞的数量增加，作为压实的结果，从1930至3220 d^<-1>/初生根。整个帽表面积覆盖着分离的细胞在压实的沙子，相比之下，约7%的表面积在松散的沙子。2.我们开发了一个图像分析程序，以量化细胞的位置在中央纵切面的根冠。只有7%的细胞在最外层的根与帽的柱区。3.机械阻抗略微增强根冠侧部分生组织的活动。细胞生产率为2，010个细胞/天<-1>（致密）和1，570个细胞/天<-1>（松散）。4.根冠的存在减少了根系穿透的机械阻力，使根系在压实的土壤中生长得更快。5.根缘细胞对根冠降低土壤阻力的贡献为58%。6.建立了一种从土壤颗粒中分离根边缘细胞的技术。湿润土壤中的根缘细胞数量显著多于干燥土壤中的根缘细胞数量，说明根缘细胞的润滑层降低了土壤入渗的摩擦阻力。