马尾松酸性根际环境中铝的化学行为——以重庆酸雨区马尾松林地土壤为例

Chemical Behavior of Aluminum in the Acidic Rhizosphere of Pinus massoniana Lamb——A Case Study on Its Cultivation in Acid Forest Soil in Chongqing, China

以重庆酸雨区马尾松林地土壤为例,通过马尾松幼苗盆栽试验法研究了酸性土壤–马尾松根系界面铝(Al)的化学行为.林地土壤中的铝可分级为交换态铝(Alex)、有机态铝(Alor)、氧化态铝(Alox)、碳酸盐态铝(Alc)和不溶态铝(Alin).研究结果表明:共存盐基离子Ca^(2+)、Mg^(2+)、K^+和Na^+对Al^(3+)在土壤–马尾松根系界面行为的影响呈正效应(缓解铝毒),影响顺序为Ca^(2+)>Mg^(2+)>K^+≈Na^+.全氮和全磷含量与根系铝含量呈正相关;土壤有机质(Organicmatter,OM)含量与根际Alor浓度呈正相关.土壤pH值(<5.0)与根际Alex呈负相关,根际Alex大于非根际Alex,马尾松根系铝的吸收主要取决于根际土壤Alex含量,Alex进入根系后逐步与根细胞壁小分子有机化合物配位,主要以Alor累积于根部.

The chemical behavior of aluminum in the acidic soil-root interface of Pinus massoniana Lamb seedlings was investigated by planting them in pots. The Al in soil was fractionated into five operationally defined forms [exchangeable （Alex）, carbonate （Alc）, oxide （Alox）, organic （Alor）, and insoluble （Alin） species]. The results showed： 1） coexisted base ions （Ca^（2＋）,Mg^（2＋）, K~＋, Na~＋） were positively related to Al^（3＋） tolerance in soil-root interface, and their alleviation followed a decreasing order： Ca^（2＋）Mg^（2＋）K~＋≈Na~＋; 2） the contents of total P and N had positive effects on the Al accumulated in the roots; and 3） the organic matter （OM） was positive to the Alor in P. massonian rhizosphere. Besides, soil pH （5.0） was negatively related to the rhizospheric Alex. Alex concentration was always higher in the rhizosphere than in bulk soil. The accumulated amount of Al absorbed in the plant roots mainly depended on the Alex quantity of the rhizosphere soil. The Alex entered into the roots and gradually complexed with the small organic molecules in root cell wall, mainly accumulated in the roots as Alor species. Fig1, Tab5, Ref 20