【摘要】 研究了香港茶园天然生态系统中铝超积累植物和铝排斥植物包括茶树 ( Camellia sinensis L.)、多花野牡丹 ( Melas-toma affine L.)、假苹婆 ( Sterculia lanceolata L.)、大罗伞紫金牛 ( Ardisia crenata L.)、相思树 ( Acacia formosa L.)和红楠 ( Machilusthunbergii Machilusthunbergii L.)对铝吸收和累积的机理。 6种植物新鲜根和茎的 p H值变化范围为 3～ 6 ,不同部位全铝含量变化幅度为 1 3～ 1 2 81 0 mg/kg(干重 ,下同 )。新鲜植物组织的 p H值是控制植物对铝吸收、转运和累积的最重要的因素。植物中的铝浓度随其 p H值降低而显著增加。供试 6种植物可分成两组 :一组是铝排斥植物 ,其 p H值大约 6 ,叶中含铝量范围为 1 7～ 1 5 1 mg/kg,包括假苹婆、大罗伞紫金牛、相思树和红楠 ;另一组是铝超积累植物 ,其 p H值为 3和 4 .5 ,叶中含铝量范围为 782 0～ 1 2 81 0 mg/kg,包括茶树和多花野牡丹。铝超积累植物新鲜根中水溶性铝与全铝的比例 ( 0 .1 1～ 0 .88)高于铝排斥植物根中的比例 ( 0 .0 4～ 0 .0 7)。相同趋势可见于茎和叶中 ,特别在多花野牡丹茎叶中。结果表明 :新鲜根、茎和叶中水溶性铝与全铝的比例高可以增加植物从土壤 -植物系统中铝的迁移速率 ,导致较高的铝吸收和累积。根际和非根际土更多还原

【Abstract】 Mechanisms for Al uptake and accumulation in Al-excluders and Al-hyperaccumulators namely Camellia sinensis, Melastoma affine, Sterculia lanceolata, Ardisia crenata, Acacia formosa and Machilus thunbergii were investigated in the natural ecosystem of a tea plantation in Hong Kong. The pH values of the fresh stems and roots of 6 plant species varied from 3 to 6 and total Al concentrations in different parts of the 6 plant species ranged from 13～12810 mg/kg. It is apparent that pH of fresh plant tissues was the most important factor controlling Al uptake, translocation and accumulation in plants. The Al concentrations in plants were significantly increased with the decrease of pH. Based on the obtained results, the plants could be classified into 2 groups: Al excluders with pH around 6 and Al contents 17～151 mg/kg in leaves including S.lanceolata, A. crenata, A. formosa and M. thunbergii, and Al hyperaccumulators with pH about 3 and 4.5 and Al contents 7820～12810 mg/kg in leaves including C. sinensis and M. affine. The ratio of water-soluble Al to total Al in fresh roots was much higher in Al hyperaccumulators (0.11～0.88) than Al excluders (0.04～0.07). A similar trend was found in fresh leaves and stems, especially in the case of M. affine. The results indicated that a higher ratio of water-soluble Al to total Al in fresh roots, leaves and stems seemed to increase Al translocation rate within the soil-plant system, leading to a higher Al uptake and accumulation. pH values between rhizosphere soil and non-rhizosphere soil were statistically significant. In general, Al hyperaccumulators, such as M. affine, had low pH values in plant tissues and decreased rhizosphere pH and rendered Al more available for uptake. Al excluders increased pH values in the rhizosphere soil to avoid higher Al uptake by roots.更多还原