钙对李氏禾富集和耐受铬的调控作用

通过水培实验，研究钙对铬胁迫下李氏禾幼苗生理生化、草酸分泌及铬吸收量的影响，考察钙对李氏禾体内草酸合成的调控，进而促进李氏禾的铬耐性富集能力的作用。结果显示，不同浓度Cr³⁺胁迫下缺钙处理，李氏禾生长受抑制及质膜过氧化作用加剧，体内总草酸含量为对照处理的113%~169%，且主要表现为水溶性草酸含量显著高于对照，水溶性草酸含量为对照处理的135%~197%；高钙处理，李氏禾细胞膜透性、丙二醛（MDA）含量低于对照，李氏禾叶部总草酸含量为对照处理的125%~155%，且主要表现为不溶性草酸含量显著高于对照，其含量为对照处理的181%~270%。低浓度（0.2、0.4 mmol/L）铬胁迫下，高钙处理总铬含量分别为对照处理的175%和215%，高浓度（0.8、1.0 mmol/L）铬胁迫下，总铬含量与对照处理无显著差异（P>0.05）。可见，添加Ca²⁺能在一定Cr³⁺浓度胁迫下，有效缓解铬对李氏禾的毒害，且能通过提高植物体内不溶性草酸含量达到促进植物富集和耐受铬的能力。

Regulation of calcium on accumulation and tolerance of Leersia hexandra Swart under Cr3+ stress

The relationship between calcium and Cr³⁺ tolerance in an accumulating plant Leersiahexandra Swartz was studied by hydroponics experiments. The results showed that under calcium deficiency,the content of total oxalate in Leersiahexandra Swartz approached 113%~169% of that of the control group,and the increase of the total oxalate content was characterized by the increase of the water-soluble oxalate which accounting for 135%~197% of that of the control group. But the growth of Leersiahexandra Swartz was adversely affected and the damage of membrane lipid peroxidation of plant was accelerated. With the addition of 10 mmol/L Ca²⁺ solution,the electrolyte leakages and the membrane lipid peroxidation of plant significantly decrease. The content of total oxalate was about 125%~155% of that of control group,and the increase of the insoluble oxalate accounted for 181%~270% of that of control group. And by 10 mmol/L Ca²⁺ addition treatment,the total chromium concentration of Leersiahexandra Swartz which grown in a nutrient solution containing 0.2 and 0.4 mmol/L Cr³⁺ reached 125%~155% of that of the control group,but there was no significant difference between the control group and the high concentration of Cr³⁺ (0.8 and 1.0 mmol/L) groups. These results suggested that calcium may act as an important role to effectively promote the oxalic acid and chelate with oxalic acid chromium,and takes part in detoxifying chromium in internal of process of Leersiahexandra Swartz.