杉木不同径级根系木质部的水力功能性状及其与解剖结构的关联性

Xylem hydraulic functional characteristics in different diameter roots and their correlations with anatomical structures of Chinese fir saplings

全球变暖导致干旱强度增大、频率增加,开展植物根系的水力功能及解剖结构特征的研究,对揭示植物的耐旱机理、提高其水分利用效率具有重要的理论及实践意义.以3年生杉木[Cunninghamia lanceolata(Lamb.)Hook.]幼树为研究对象,研究不同径级杉木根系(0-2 mm,2-5 mm和5-10 mm)水力功能性状、解剖结构特征及其二者的相关性,结果表明:导水率、管胞直径、水力直径、纹孔膜直径、纹孔口直径、纹孔膜面积、纹孔塞面积随着杉木根系径级的增加而增大,根系比导率、单位质量导水率、管胞密度、木质部密度、水势随根系径级的增加而减小,细根与中根、粗根之间差异均达显著水平(P<0.05).相关分析结果表明,根系的导水率与管胞直径、水力直径、纹孔膜直径、纹孔膜面积和纹孔塞面积呈极显著正相关(P<0.01),根系的比导率、单位质量导水率与管胞密度、木质部密度呈极显著正相关,与纹孔膜直径、纹孔口直径和纹孔膜面积呈极显著负相关.可见,杉木不同径级根系的水分输导状况受管胞结构及纹孔特征的共同影响,粗根和中根具有相对较大的管胞直径、纹孔膜直径、纹孔口直径等解剖结构,使其具有更大的水分输导能力,而细根具有较大的木质部密度、管胞密度、纹孔密度等解剖结构以及较高的水势,这些高效率的输水结构使其水分运输更具安全性.

Under the background of increasing drought intensity and frequency caused by global warming,understanding the hydraulic functions and anatomical structures of roots is of great theoretical and practical significance for revealing the drought tolerance mechanisms of plants and improving water use efficiency.Using 3-year-old Cunninghamia lanceolata(Lamb.),root hydraulic function properties and anatomical structures of hook saplings with different diameter classes(0-2,2-5,and 5-10 mm)were studied,and the correlations between them were discussed.The results showed that hydraulic conductivity,tracheid diameter,hydraulic diameter,pit membrane diameter,pit aperture diameter,pit membrane area,and pit torus area increased with increasing root diameter,whereas root specific conductivity,hydraulic conductivity per unit mass,tracheid density,wood density,and water potential decreased with increasing root diameter.The differences in the above indices were significant between fine roots and the other two root diameters(P<0.05).Root hydraulic conductivity was significantly and positively correlated with tracheid diameter,hydraulic diameter,pit membrane diameter and area,and pit torus area(P<0.01).Specific conductivity and hydraulic conductivity per unit mass were significantly positively correlated with tracheid density and wood density and were significantly negatively correlated with pit membrane diameter,pit aperture diameter,and pit membrane area.In conclusion,the tracheid structure and pit characteristics of roots of different diameters jointly regulate water transport efficiency.The larger tracheid diameter,hydraulic diameter,pit membrane diameter,and pit torus diameter of large and medium roots make them more prone to higher water transport capacity,whereas fine roots have more efficient water transport channels,such as higher wood density,tracheid density,pit density,and higher water potential,which ensures that they have higher water transport security.