油茶根系吸收铝导致生长介质酸化

选用油茶为试验材料，采用固体琼脂培养和溶液培养两种试验体系，研究了油茶根系吸收铝离子与生长介质pH变化的关系。琼脂培养试验结果表明，在钙离子和铝离子介质中，油茶根际区域均发生了明显的酸化；溶液培养试验结果进一步表明，阳离子的吸收尤其是铝离子的吸收是介质酸化的原因，铝与钙同时存在时，溶液酸化主要是由铝离子的吸收引起的。另外，随着溶液铝浓度的增加，溶液pH下降幅度增加，二者之间呈现极显著正相关关系，且油茶培养时间越长，溶液pH下降越多。所有这些结果表明油茶吸收铝会降低生长介质pH。

Acidification of growth medium under Al absorption by roots of oil tea

Long-term cultivation of camellia plants can lead to soil acidification, but the main mechanisms are still unclear. Oil tea (Camellia oleifera Abel.) of camellia as an Al accumulator was selected to investigate the effects of Al absorption on medium acidification by agar culture and hydroponic culture. The results showed that rhizospheres of oil tea were acidified in agar medium with Ca ion or Al ion. The absorption of cations, especially Al ion, was the reason of medium acidification, and when Al and Ca co-existed, medium acidification was primarily caused by the absorption of Al ion. In addition, with the increase of Al concentration in solution, the decline of pH value increased significantly, and there was a positive correlation between pH decrease and Al concentration. The longer culturing time increased pH reduction. These results indicated Al absorption by oil tea could induce pH decrease of growth medium.