中文摘要：

香根草因其具有发达的根系而被许多国家用于水土保持，但紧实土壤影响根系的生长，而土壤容重与土壤紧实度密切相关。为了掌握粤西野生香根草对紧实土壤的适应状况，用人工土柱研究了容重分别为1．20 g／cm3（D1．20）、1．35 g／cm3（D1．35）和1．58 g／cm3（D1．58）的土壤对其根系形态和生物量的影响。结果表明：1）随容重增大，根系和地上部生物量下降，根冠比降低，植株的根表面积、根长密度和根体积密度减小，而平均根直径增大。2）容重影响根系的空间分布，D1．20和 D1．35处理的根系在上、下层分布较多，中间层分布少，表明粤西野生香根草具有深根型特性；高容重阻止根向下延伸，D1．58处理的根系主要分布0～6 cm 的土层内。3）D1．20和 D1．35土壤的平均根直径随土层加深减小，而 D1．58的则增加。本实验结果说明粤西野生香根草能耐较紧实（D1．35）的土壤，高紧实土壤（D1．58）虽然限制其生长，但对表土层根系的分布影响小。并就容重对粤西野生香根草固土护坡的影响进行了讨论。

英文摘要：

Vetiver grass （Vetiveria zizanioides ）has an extensive root system and is consequently used world-wide for water and soil conservation.However,soil compaction resulting in high soil bulk density negatively influences root growth.In order to understand the adaptation of vetiver grass to soil compaction,the effects of soil of different bulk density,1.20 g/cm3 （D1 .20 ）,1.35 g/cm3 （D1 .35 ）and 1.58 g/cm3 （D1 .58 ）,on the root mor-phology and biomass of vetiver seedlings were investigated using soil columns.The results showed that shoot and root dry weight,root：shoot ratio,root surface area,root length density and root volume density decreased with increasing bulk density,but that average root diameter increased.High bulk density influenced the spatial distribution of roots;more roots grew in the upper （0-6 cm）and lower （18-24 cm）soil horizons under the D1 .20 and D1 .35 treatments,suggesting that vetiver typically produces a deep root system but that root growth is inhibited by high soil bulk density,confining roots to the upper soil horizon （0-6 cm）.The average root diam-eter in the D1 .20 and D1 .35 treatments decreased but increased in D1 .58 with increasing soil depth.It is concluded that vetiver grass could tolerate moderately compacted soil.