水作和旱作对叶菜吸收镉的影响差异研究

采用盆栽试验,以适宜水旱2种模式栽培的空心菜（Ipomoea aquatica）为对象,研究了水作和旱作两种栽培模式对Cd污染土壤上空心菜吸收积累Cd的差异及其影响因素。结果表明,水作和旱作对空心菜生物量和Cd质量分数影响显著。水作条件下,空心菜地上部和根系生物量分别比旱作处理增加了16.3%和190.6%,而地上部和根系Cd质量分数则较旱作处理降低了52.2%和49.3%。水作和旱作对土壤pH和DTPA-Cd质量分数也有不同影响,其中种植空心菜的处理土壤pH较旱作处理增加了0.99个单位,土壤DTPA-Cd质量分数降低了40.0%,不种空心菜的处理土壤pH较旱作处理增加了1.48个单位,土壤DTPA-Cd质量分数降低了30.4%。逐步回归分析发现,空心菜地上部Cd质量分数受土壤DTPA-Cd质量分数和土壤pH影响最大。因此,在Cd污染土壤上,通过旱作改水作可降低空心菜可食部分Cd质量分数,是一种环境友好、价格低廉的土壤重金属污染的调控措施。

Comparison between water-submerging-cultivation and dry farming in reducing Cd concentration in waterspinach

In order to reduce Cd concentration in vegetables,a pot experiment was carried out to verify if water-submerging-cultivation can decrease Cd uptake by waterspinach（Ipomoea aquatica） grown in contaminated soil comparing with the normal dry farming.Results showed that there were significant differences between the water-submerging-cultivation and the dry farming in biomass and Cd concentration of water spinach.The water-submerging treatment increased shoot and root fresh biomass of waterspinach by 16.3% and 190.6%,respectively,while decreased shoot and root Cd concentration in waterspinach by 52.2% and 49.3%,respectively,compared to the dry-farming.For soil pH and DTPA-extractable Cd content,significant difference was observed between the two water patterns.With the waterspinach planting,soil pH increased 0.99 unit under the water-submerging treatment than that of the dry-farming,and soil DTPA-Cd decreased by 40.0%.Without planting,soil pH under the water-submerging treatment was also higher than that of the dry-farming treatment by 1.48 unit,and soil DTPA-Cd decreased by 30.4%.Stepwise regression analysis indicated that the dominant factors controlling shoot Cd concentration in waterspinach were soil DTPA-Cd and soil pH.Thus,water-submerging cultivation might be an eco-friendly and low-cost measure to reduce Cd concentration in waterspinach grown in Cd-moderately-contaminated soils.