5种草本植物根系理化特性及其相关性

Relationship between root tensile mechanical properties and main chemical components of five herbaceous species

为理解草本植物根系的主要化学成分对根系力学特性影响,选取武汉地区5种常见的水土保持草本植物,开展了根系抗拉特性研究。根系直径范围选取0~1.5mm,按直径分成4个径级,并按根系分级测定了纤维素、木质素和半纤维素含量,计算了综纤维素含量和木纤比。结果表明,5种根系4个径级的抗拉力、抗拉强度均表现为香根草(Vetiveria zizanioides)>百喜草(Paspalum natatu)>狗牙根(Cynodon dactylon)>马尼拉草(Zoysia matrella)>狗尾草(Setaria viridis)。香根草和百喜草的根系具有较大的抗拉力学特性,与其它3种植物根系的抗拉力学特性差异显著(P<0.05)。随着直径增大,5种根系抗拉力均增大,而抗拉强度均减小,两者均表现为幂函数关系。5种植物不同径级根系纤维素含量范围为21.90%~34.57%,木质素含量为12.85%~19.42%,半纤维素含量为14.31%~20.22%,综纤维素含量为38.52%~51.83%,木纤比为0.37~0.90。根系抗拉力与纤维素、综纤维素含量显著负相关(P<0.05),与木纤比显著正相关(P<0.05);抗拉强度则均与纤维素、综纤维素含量显著正相关(P<0.05),与木质素含量、木纤比显著负相关(P<0.05)。纤维素、木质素、综纤维素含量和木纤比与5种草本植物根系的力学性质有较好的相关关系。研究结果表明,香根草和百喜草可作为武汉重要的固土护坡植物种类,为分析植物根系力学、化学性质和直径的相互作用关系提供理论依据。

To explore the effect of root chemical components on the mechanical properties of five common herbaceous species in Central China,root tensile tests were conducted on their roots.The tested roots were divided into four groups with diameters ranging from 0to 1.5 mm,and then their root chemical components such as cellulose,lignin,and hemicellulose content were measured.In addition,the holocellulose and ratio of lignin to cellulose contents were calculated.The results showed that the root tensile force and strength of the five species were in the following descending order：Vetiveria zizanioides〉Paspalum natatu〉Cynodon dactylon〉Zoysia matrellaSetaria viridis in each diameter class.A comparison of the different species in each group revealed that the tensile properties of V.zizanioides and P.natatu were significantly higher than those of the other three species were（P〈0.05）.Furthermore,the different diameter classes of the five species showed a significantly increased tensile force while the tensile strength decreased significantly with increasing root diameter.Both the tensile force and strength were shown to be power functions（P〈0.05）.The analysis of the root chemical components showed that the values were in the range of 21.90% ~34.57%,12.85% ~19.42%,14.31%~19.34%,38.52%~51.83%,and 0.37~0.83 for the cellulose,lignin,hemicellulose,holocellulose,and ratio of lignin to cellulose content,respectively.Interestingly,the root diameter of the five species was negatively correlated with the cellulose and holocellulose contents but positively correlated with the lignin and the ratio of lignin to cellulose contents.However,no significant correlation was found between the hemicellulose content and root diameter.The root tensile force was negatively correlated with the cellulose and holocellulose content,and positively correlated with the ratio of the lignin to cellulose content while the root tensile strength was positively correlated with the cellulose and holocellulose content,and negatively correlated with the lignin and the ratio of lignin to cellulose content.All the correlations were statistically significant,and the above the results indicate that cellulose,holocellulose,lignin,and the ratio of lignin to cellulose contents exhibited a good correlation with the mechanical properties of the herbaceous species roots.Therefore,this study provided useful information on the relationship between the mechanical properties,chemical components,and diameter of these plant roots.