Abstract: In order to study the genotypic differences of phosphorus efficiency and relationship between phosphorus efficiency and root structure of Stylosanthes spp. under different phosphorus levels, three genotypes of Stylosanthes, including Pinefficient, Pefficient and Psensitive, were used as materials. Phosphorus nutrition characteristics of different genotypes of Stylosanthes spp. under 7 phosphorus treatments with concentrations of 0, 0020, 0035, 0050, 0075, 0100 and 0200 g·kg-1 were investigated. Root growth status of seedling stage of two representative genotypes (Pinefficient and Pefficient) were detected under phosphorus treatments of control (0 g·kg-1), Pdeficiency (0010 g·kg-1), and normal (0025 g·kg-1), so as to determine the relationship between root structure and phosphorus efficiency. The results showed that phosphorus content and phosphorus uptake of different Stylosanthes genotypes increased with the increase of phosphorus concentration, while phosphorus utilization efficiency had an opposite tendency. Phosphorus use efficiency of Pefficient genotype in all phosphorus treatments was the highest. With the increase of phosphorus concentration, the change ranges of phosphorus use efficiency of different genotypes showed the trend as following: Pefficient < Pinefficient < Psensitive. With the increase of phosphorus stress, number of lateral root, length of main root, root volume, surface area of root and active absorption area of root in Pefficient and Pinefficient genotypes both increased, while the root diameter both decreased. Root volume of Pefficient genotype was significantly higher than that of Pinefficient genotype, and it was better than that of Pinefficient genotype in other root configuration indexes. Varieties of Pefficient genotype were more tolerant to low phosphorus condition. Moreover, root morphology of Stylosanthes spp. was an important mechanism for adapting to low phosphorus stress. Present research provided a theoretical basis for high quality cultivation of Stylosanthes spp..

Key words: Stylosanthes spp., phosphorus supply, phosphorus efficiency, root architecture, response mechanism

摘要： 为研究不同磷水平下柱花草磷效率的基因型差异及其与根构型的关系，利用盆栽试验，以磷低效、磷高效、磷敏感3种基因型柱花草品种为材料，研究0、0020、0035、0050、0075、0100、0200 g·kg-1共7个磷水平下，不同基因型柱花草的磷营养特性；并进一步比较两个代表性基因型（磷低效、磷高效）柱花草在对照(0 g·kg-1)、缺磷(0010 g·kg-1)、正常磷（0025 g·kg-1）处理下苗期根系生长状况，从而确定根构型与磷效率的关系。结果表明：不同基因型植株的磷含量、吸磷量随磷浓度的增加而增加，磷利用效率对磷浓度的反应趋势则相反。在不同磷处理下，磷高效基因型的磷利用效率均较高，且随着磷浓度的增加不同基因型品种磷利用效率的变化趋势度表现为：磷高效＜磷低效＜磷敏感。随着磷胁迫的加重，磷高效和磷低效基因型的侧根数、主根长、根体积、根表面积和根活跃吸收面积均增加，根直径减小。磷高效基因型柱花草根体积显著高于磷低效基因型，且在其他根构型指标上优于磷低效基因型。磷高效基因型品种较耐低磷，柱花草根系形态的改变是其适应低磷胁迫的重要机制。研究为柱花草的优质栽培提供理论依据。

关键词: 柱花草, 供磷水平, 磷效率, 根构型, 响应机制