假稻对铬的富集作用及其耐受能力研究

假稻属的李氏禾（Leersia hexandra）是中国境内发现的铬超富集植物。研究以其同属植物假稻（Leersiajapon ica）为材料,测定了假稻对铬（Cr^3＋）的富集能力及其在模拟铬污染的实验条件下的光合、生理和根系形态学指标。结果发现：（1）在0～40 mg·L^-1的Cr^3＋浓度范围内,假稻根茎和叶中铬的含量随铬质量浓度的提高而升高,在培养液中铬浓度为40 mg·L^-1时,根茎中铬含量高达2 292.00 mgLkg^-1,其生物富集系数为57.30;（2）浓度为10～40 mg·L^-1的Cr^3＋处理对假稻的叶绿素a和b含量、胞间CO2浓度（Ci）和气孔限制（LS）和净光合速率无明显影响;（3）叶片中脯氨酸含量变化趋势呈单峰型,在20 mg·L^-1的Cr^3＋时假稻叶片脯氨酸含量达到最高;（4）随着Cr^3＋浓度的升高,假稻根系的根尖数表现出升高的趋势,而根表面积（相对于对照组）也表现出增加的趋势。以上结果表明,假稻的根茎对Cr^3＋有很强的富集能力,且对Cr^3＋有较强的耐受性,这种耐受性有其光合生理和根系形态学上的基础,说明假稻在净化铬（Cr^3＋）污染的水体环境上很有应用前景。

On Bioaccumulation and Endurance of Leersia Japonica to Chromium

Leersia Hexandra is one of the Cr-hyperaccumulators discovered in China.Leersia japonica is a species belonging to the same genus.In hydroponic experimental condition,we examined the bioaccumulation capacity of L.japonica to chromium,and its photosynthesis,physiological and root morphology.We found that：（1） Cr concentration in rhizome and leave of L.japonica increased from 0 to 40 mg·L^-1 chromium（Cr^3＋）,reaching 2 292.00 mgLkg^-1 with a bioaccumulation of 57.30 in rhizome when treated with Cr^3＋ at 40 mg·L^-1.（2） there was little influence of chromium from 10 to 40 mg·L^-1 on photosynthesis,contents of chlorophyll a and b,intercellular CO 2 concentration and stomatal limitation of L.japonica;（3） the proline content in leaves varied from low to high,then to low when treated with Cr^3＋ from 10 to 40 mg.L^-1,with a peak at 20 mg·L^-1.（4） the tip number and root surface of L.japonica increased with the chromium concentration.The above results indicate that L.japonica could significantly accumulate chromium and has stronger tolerance to chromium,and it could be applied in the phytoremediation of Cr-contaminated soil and water.