School of Hydraulic and Electric Power, Heilongjiang University, Harbin, China.
School of Traditional Chinese Medicine, Zhejiang Pharmaceutical College, Ningbo, China.
PLoS One. 2021 Oct 28;16(10):e0259117. doi: 10.1371/journal.pone.0259117. eCollection 2021.
Xylem tracheids are the channels for water transport in conifer. Tracheid flow resistance is composed of tracheid lumen resistance and pit resistance. The single tracheid structure parameters in the stem and root of Sabina chinensis were obtained by dissociation and slicing, combined with numerical simulation to analyze the tracheid flow resistance characteristics. The results showed that the tracheid lumen resistance was determined by the tracheid width and tracheid length. The pit resistance was determined by the number of pits and single pit resistance. The single pit resistance was composed of four elements: the secondary cell wall, the border, the margo and the torus. The margo contributed a relatively large fraction of flow resistance, while the torus, the border and the secondary cell wall formed a small fraction. The size and position of the pores in the margo had a significant effect on the fluid velocity. The number of pits were proportional to tracheid length. The power curve, S-curve and inverse curve were fitted the scatter plot of total pit resistance, total resistance, total resistivity, which was found that there were the negative correlation between them. The three scatter plot values were larger in the stem than in the root, indicating that the tracheid structure in the root was more conducive to water transport than the stem. The ratio of tracheid lumen resistance to pit resistance mainly was less than 0.6 in the stem and less than 1 in the root, indicating that the pit resistance was dominant in the total resistance of the stem and root.
松柏类植物木质部管胞是水分运输的通道。管胞阻力由管胞腔阻力和纹孔阻力组成。通过解离和切片获得了圆柏茎和根中单根管胞的结构参数，结合数值模拟分析了管胞阻力特性。结果表明，管胞腔阻力由管胞宽度和管胞长度决定。纹孔阻力由纹孔数量和单个纹孔阻力决定。单个纹孔阻力由次生壁、边框、边缘和轮缘四个部分组成。边缘对阻力的贡献较大，而轮缘、边框和次生壁的贡献较小。边缘上的孔的大小和位置对流速有显著影响。纹孔数量与管胞长度成正比。总纹孔阻力、总阻力和总电阻率的散点图拟合幂曲线、S 曲线和倒数曲线，发现它们之间呈负相关。三个散点图的值在茎中大于根中，表明根中的管胞结构比茎更有利于水分运输。管胞腔阻力与纹孔阻力的比值在茎中主要小于 0.6，在根中主要小于 1，表明在茎和根的总阻力中纹孔阻力占主导地位。
