玉米/大豆间作的镉累积规律初探

为探索镉污染农田高效种植结构调整模式,通过在镉污染严格管控区农田(土壤全镉含量1.98 mg·kg~(-1))开展不同镉积累特性的玉米和大豆间作试验,系统研究了单作和间作下玉米和大豆的镉吸收积累规律。结果表明,随着生育进程推进,玉米秸秆镉含量呈总体降低的变化趋势,大豆秸秆镉含量呈逐渐升高再降低的趋势,玉米苗期秸秆镉含量最高,而大豆鼓粒期秸秆镉含量最高;大豆成熟期籽粒镉含量高于鼓粒期,玉米灌浆期籽粒镉含量高于成熟期;间作降低了成熟期镉低积累玉米籽粒镉含量,提高了镉高积累玉米籽粒镉含量,间作模式下镉高积累和低积累玉米品种籽粒镉含量平均值分别为0.139 mg·kg~(-1)和0.003 mg·kg~(-1),分别较单作降低了-14.88%和88.46%;秸秆和籽粒的富集系数大豆分别为2.567～3.329和0.667～0.764,玉米分别为0.729～3.339和0.001～0.079,间作玉米秸秆富集系数较单作增加0.15%～46.22%,低镉积累玉米籽粒富集系数较单作降低84.62%～92.31%;间作处理土地当量比为1.46～1.77。因此,间作大豆可以保证低镉积累玉米籽粒在镉污染土壤的安全生产,为土地合理利用提供有效的参考途径。

Primary research on cadmium accumulation in maize and soybean intercropping system

To explore the mode of efficient planting structure adjustment in cadmium-contaminated areas, a strictly-controlled cadmium pollution fallow field(soil total cadmium content of 1.98 mg·kg^-1)located in Hunan Province was selected to examine the cadmium absorption and accumulation trends of different cadmium accumulations in maize and soybean monocultures(sole maize and sole soybean) and maize and soybean intercropping. The results indicated that the straw cadmium content of maize showed a gradually decreasing trend with increase in growth time. The straw cadmium content of soybean first showed a gradually increasing and then decreasing trend with increase in growth time. The cadmium content was the highest in maize straw in the seedling stage, while it was the highest in soybean straw in the seed-filling period. The cadmium content of the seed-filling period was lower than that of the mature stage in soybean seeds. The cadmium content of the filling stage was higher than that of the mature stage in maize seeds. In the mature stage, the grain cadmium content of low cadmium maize decreased, whereas that of high cadmium accumulation maize increased in the intercropping system. The average grain cadmium contents of high and low cadmium maize in the intercropping system were 0.139 mg·kg^-1 and 0.003 mg·kg^-1, which were -14.88% and 88.46% lower, respectively, than those of the monocultures. The straw and grain bio-accumulation coefficients corresponding to soybean were 2.567~3.329 and 0.667~0.764; those in maize were 0.729~3.339 and 0.001~0.079, respectively. The intercropped maize straw bio-accumulation coefficients increased by 0.15%~46.22% more than those of the single maize cultivation. The grain bioaccumulation coefficients of low cadmium accumulation maize decreased by 84.62%~92.31% more than those of the single maize cultivation. The land equivalent ratio of the intercropping treatment was 1.46~1.77. Therefore, the low cadmium accumulation maize and soybean intercropping system is an effective method for the safe development of maize grains in cadmium-contaminated soil along with rational land use.