铜胁迫对蓖麻根系有机酸分泌及Cu吸收的影响

Influence of Copper Absorption and Organic Acid Exudation in Ricinus communis L. Root under Copper Stress

通过盆栽试验并结合原子分光光度法和高效液相色谱法,研究了土壤Cu浓度对蓖麻根系有机酸分泌及Cu吸收的影响。结果表明,蓖麻对Cu表现出较强的转运、富集能力,根部是积累Cu的主要器官。蓖麻根分泌物中含有草酸、苹果酸、乳酸、柠檬酸和酒石酸,其中草酸、苹果酸含量分别占39.93%和31.53%。各种有机酸对Cu的响应不同,草酸含量随土壤Cu浓度升高逐渐减少。土壤Cu浓度<300 mg/kg时,酒石酸、苹果酸、乳酸和柠檬酸含量随着Cu浓度升高而上升,土壤Cu浓度为300 mg/kg时达到最大,分别为对照的6.887、1.497、2.058和2.346倍;土壤Cu浓度>300 mg/kg时,苹果酸、乳酸、柠檬酸含和酒石酸含量随着Cu浓度升高而逐渐减少。苹果酸含量与蓖麻的Cu含量的相关系数最大,其次是乳酸、草酸和柠檬酸。因此,蓖麻对Cu的转移和富集中苹果酸可能发挥主导作用,乳酸、草酸和柠檬酸次之。

Influences of copper concentration in soil on copper absorption and organic acid exudation of castor （Ricinus communis L. ） root were determined by atomic spectrophotometry and high performance liquid chromatography. Results show that castor has the strong ability of enrichment and transshipment in pot experiment, root is the major organ of accumulating copper. Oxalic acid, lactic acid, citric acid, tartaric acid and malic acid are detected in castor root secretion, with oxalic acid and malic acid content as 39.93% and 31.53% respectively. The organic acid varies responses to copper. Oxalic acid content is dropping with copper concentration. When copper was 300 mg/kg, the content of actic acid, citric acid, tartaric acid and malic acid are the highest, 6.887, 1.497, 2.058 and 2.346 times to the control respectively. Organic acid contents increase in lower copper concentration less than 300 mg/kg, and reduce in higher concentration more than 300 mg/kg. The correlation coefficient of copper in castor and malic acid is the largest, so the malic acid may be playing the leading role in enriching and transferring copper, and then followed by lactic acid, oxalic acid and citric acid.