印度芥菜-苜蓿间作对镉胁迫的生态响应

采用温室盆栽试验，研究了重金属镉（Cd）胁迫对印度芥菜和苜蓿间作下的土壤-植物系统的影响，同时对苜蓿的Cd饲用安全进行了评估.结果表明：在土壤Cd含量为0.37～20.37 mg·kg^-1范围内，与单作印度芥菜和苜蓿相比，间作使印度芥菜生物量降低了0.4%～11.8%，而使苜蓿生物量提高了55.3%~70.0%.土壤有效Cd主要受土壤全量Cd和种植植物种类的影响，种植方式对其影响不大.在土壤Cd含量为5.37 mg·kg^-1时，间作印度芥菜地上部Cd含量较单作提高了14.5%，而间作苜蓿地上部Cd含量较单作降低了57.1%；此时，单作和间作苜蓿地上部Cd含量分别为0.21和0.09 mg·kg^-1，均未超过饲料卫生限定标准(0.5 mg·kg^-1).在土壤Cd含量为10.37～20.37 mg·kg^-1范围内，虽然单作和间作苜蓿Cd含量均超过饲料卫生限定标准，但间作种植方式仍然使苜蓿地上部Cd含量较单作降低了2.8%～48.3%，印度芥菜地上部Cd含量也较单作降低了1.1%～48.6%.不论单作还是间作印度芥菜的Cd转运系数都远高于苜蓿.

Ecological responses of Brassica juncea-alfalfa intercropping to cadmium stress

A pot experiment was conducted to study the effects of cadmium (Cd) stress on the soil-plant system under Brassica juncea-alfalfa intercropping, and to evaluate the Cd feed safety of alfalfa. Comparing with monoculture, when the soil Cd content was in the range of 0.37-20.37 mg·kg-1, intercropping decreased the B. juncea biomass by 0.4%-11.8% while increased the alfalfa biomass by 55.3%-70.0%. Soil available Cd was mainly determined by soil total Cd and plant species, and less affected by planting pattern. Comparing with monoculture, when the soil Cd content was in the range of 0.37-5.37 mg·kg-1, intercropping increased the Cd content in above-ground part of B. juncea by 14.5%, but decreased the Cd content in above-ground part of alfalfa by 57.1%. The Cd contents in the above-ground parts of alfalfa under monoculture and intercropping were 0.21 and 0.09 mg·kg-1, respectively, neither of them being over the feed safety standard (0.5 mg·kg-1). When the soil Cd content was in the range of 10.37-20.37 mg·kg-1, though the Cd contents of mono-cultured and intercropped alfalfa were both over the standard, the Cd contents in the above-ground parts of alfalfa and B. juncea under intercropping were decreased by 2.8%-48.3% and 1.1%-48.6%, respectively. Under both monoculture and intercropping, the Cd transport coefficient of B. juncea was far greater than that of alfalfa.