Abstract: Soil pot and hydroponic experiments with thirteen different Stylosanthes genotypes wereconducted to investigate the genetic variability of this plant in P efficiency and the morphological andphysiological mechanisms responsible for the observed genetic variation.It was found that there was greatgenetic variability in plant height, plant branching number, main root length, P uptake, P absorbing areaand root acidification.Analysis of correlation among the measured items indicated that plant height, plantbranching number, main root length, root biomass and P absorbing area were closely related to shootbiomass.The significant correlation between root acidification and P uptake showed that root acidificationis advanageous to P uptakd of Stylosanthes.However, the phosphatase activities Of roots or leaves or thenitrogen fixaion activities was not signficanly correlated with shoot biomass or plant P uptake, and P effi-ciency of Stylosanthes was maianly determined by P uptake efficiency.

Key words: Red soil, Stylosanthes, P efficiency, Genotypic variation

摘要： 本文通过盆栽及水培试验对桂花草地上部、根部形态、根际酸化及根、叶酸性磷酸酶活性等生理生化特性的测定,对柱花草基因型适应低磷的机制进行研究,为选育磷高效率基因型提供依据。结果表明,在酸性低磷红壤区,供试的十三个桂花草品种在株高、分枝数、主根长、根系活跃吸收面积及根际酸分泌等方面差异明显。相关分析结果表明,地上部生物量与株高、分校数、主根长和根系活跃吸收面积等形态特征间相关关系明显。在低磷区,根际酸化能力与植株吸磷量之间相关关系显著,表明报际酸化有利于柱花草对磷的吸收。根部和叶部磷酸酶活性与缺磷条件下地上部生物量和植株吸磷量之间无显著相关,进而表明桂花草的磷效率主要是由吸收效率所决定的。

关键词: 红壤, 柱花草, 磷效率, 基因型差异