Hunan Institute of Agro-Environment and Ecology, Hunan Academy of Agricultural Sciences, Changsha 410125, China; Key Lab of Prevention, Control and Remediation of Soil Heavy Metal Pollution, Ministry of Agriculture Key Lab of Agri-Environment in the Midstream of Yangtze River Plain, Changsha 410125, China.
Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Science (CAS), Beijing 100101, China.
Sci Total Environ. 2023 Jun 20;878:163133. doi: 10.1016/j.scitotenv.2023.163133. Epub 2023 Mar 29.
Intercropping cadmium (Cd) hyperaccumulators with crops have been widely applied in the remediation of contaminated farmland soils. However, most studies were done on drylands since the majority of the hyperaccumulators are susceptible to the aquatic environment, making the remediation of Cd-contaminated paddy fields particularly difficult. Our study attempts to address the issue by intercropping the high-Cd-accumulating (henceforth, "high-Cd") rice cultivars with the low-Cd-accumulating (henceforth, "low-Cd") ones, and to study the Cd removal, uptake and translocation during the remediation process. The results indicated that intercropping mode with 20-cm row spacing (intercropping-20 treatment) performed better than the that with 30-cm row spacing (intercropping-30 treatment), while intercropping had stronger impact on late rice compared to early rice. In general, the physiological condition of rice was stable under the intercropping-20 treatment, suggesting the growth of rice was not impeded. For late rice, as the intercropping-20 treatment can significantly reduce soil pH and increase the diethylenetriaminepentaacetic acid extracted Cd (DTPA-extracted Cd) from the rhizosphere soil, Cd accumulated more in the tissues of the high-Cd rice cultivars (H2), and its dry biomass increased. As a result, a drastic improvement in the total Cd removal rate by 38.55 % was noticed. Therefore, the reduction of total Cd concentration in 0-20 cm profile caused by removal, thus it could provide safer soil environment for the growth of low Cd-rice cultivars (L2), leading to a significant drop in the root Cd concentration and safer production of L2. Interestingly, intercropping had no effect on the yield per plant of low-Cd rice cultivars. For early rice, intercropping-20 treatment exerted trivial effects to all aspects. The intercropping-30 treatment has poor representativeness of all indicators because of the large intercropping distance. Our results demonstrate that intercropping of the high-Cd and the low-Cd rice cultivars is a potential mode for Cd remediation in paddy fields.
间作耐镉（Cd）超积累作物已广泛应用于污染农田土壤的修复。然而，由于大多数超积累植物对水生环境敏感，因此大多数研究都在旱地进行，这使得受 Cd 污染的稻田修复变得特别困难。我们的研究试图通过间作高镉积累（简称“高 Cd”）水稻品种和低镉积累（简称“低 Cd”）水稻品种来解决这个问题，并研究修复过程中 Cd 的去除、吸收和迁移。结果表明，行距 20cm 的间作模式（间作-20 处理）比行距 30cm 的间作模式（间作-30 处理）效果更好，而且间作对晚稻的影响大于早稻。一般来说，在间作-20 处理下，水稻的生理状况稳定，表明水稻的生长没有受到阻碍。对于晚稻，间作-20 处理可显著降低土壤 pH 值，增加根际土壤中二乙三胺五乙酸提取的 Cd（DTPA 提取的 Cd），使高 Cd 水稻品种（H2）的组织中积累更多的 Cd，其干生物量增加。因此，总 Cd 去除率提高了 38.55%。因此，通过去除降低了 0-20cm 剖面中总 Cd 浓度，从而为低 Cd 水稻品种（L2）的生长提供了更安全的土壤环境，导致根系 Cd 浓度显著下降，L2 更安全地生产。有趣的是，间作对低 Cd 水稻品种的单株产量没有影响。对于早稻，间作-20 处理对各方面的影响都很小。由于间作距离较大，间作-30 处理对所有指标的代表性都较差。我们的研究结果表明，高 Cd 和低 Cd 水稻品种间作是稻田 Cd 修复的一种潜在模式。
