大豆根系分泌物和根细胞壁对难溶性磷的活化

探讨了不同磷效率大豆品种根系细胞壁和根分泌物对难溶性铝磷的活化与吸收能力。结果表明，砂培条件下，磷高效品种(巴西10号)对难溶性铝磷的吸收显著高于磷低效品种(本地2号)。铝磷处理条件下，根系总表面积巴西10号是本地2号的131％，而钾磷处理二者没有明显差异。根系细胞壁对铝磷的活化表明，大豆苗期根系细胞壁对铝磷的活化量显著高于成熟期。苗期、成熟期巴西10号对铝磷的活化量为本地2号的119％、176％。不同栽培方式根系细胞壁对铝磷的活化量表现为水培大于砂培，水培条件下两个大豆基因型对铝磷的活化量没有差异。不同生育时期、栽培方式根分泌物对铝磷的活化量表现为，成熟期大于苗期，砂培大于水培。巴西10号根分泌物对铝磷的活化量比本地2号分别高出69．3％(成熟期)和40．1％(砂培)。上述研究结果表明，大豆根分泌物和根细胞壁对难溶性铝磷的溶解具有促进作用，有利于大豆对铝磷的吸收。

Mobilization of sparingly soluble phosphates by root exudates and root cell wall of soybean seedlings

Low P availability is one of the major limitations to crop production. How to improve P efficiency is the issue tha scientific researchers in the field of soil science and plant nutrition are interested in. In this study, mobilization of aluminum-bound phosphate (Al-P) was examined by root cell wall and root exudates of two soybean genotypes with different P efficiency. Results with sand culture indicated that Brazil 10 had a higher Al-P uptake than the Local 2 did. Total root surface area of Brazil 10 was 131% of that in the Local 2 under Al-P treatment, while no difference under KP treatment. Mobilization of Al-P by root cell wall a seedling stage was significantly higher than that at mature stage. Al-P Mobilized by cell wall of Brazil at seedling and mature stages were 119 and 176% of those of the Local 2 respectively. The corresponding values under different cultivations were bigger unde solution culture than under sand culture. However, no difference in Al-P mobilization of two cultivars was observed under solution culture. Al-P mobilized by root exudates under different stages and cultivations were bigger at mature stage than at seedling stage and bigger under sand culture than solution culture. Al-P mobilized by root exudates was 69.3% (mature stage) and 40.1% (sand culture) in Brazil 10 than in the Local 2. The above results indicated that root exudates and cell wall of soybean seedlings play an important role in enhancing the mobilization of sparingly soluble phosphates, thus contribute P uptake.