施加盐基离子调控水稻Cd的吸收与累积

盐基离子含量是土壤肥力的重要指标,也是决定土壤Cd生物有效性的重要因素.为探明盐基离子对稻田系统中Cd迁移、转运与累积的影响,本研究通过水稻盆栽试验,按照土壤中盐基离子的物质的量比施加不同浓度梯度KCl、CaCl_2、NaCl和MgCl_2到模拟制备的轻度(0.5 mg·kg~(-1))和中度(1.5 mg·kg~(-1))Cd污染土壤,分析盐基离子对土壤CaCl_2提取态Cd含量和水稻吸收累积Cd的影响.结果表明:施加盐基离子能够增加土壤阳离子交换量(CEC),在轻度和中度Cd污染土壤中,土壤CaCl_2提取态Cd含量分别下降了24.6%～56.1%和17.0%～71.1%,糙米Cd含量分别降低了9.1%～60.5%和7.2%～36.0%.在轻度和中度Cd污染土壤中,糙米Cd含量与土壤CaCl_2提取态Cd含量之间存在线性正相关关系,根、茎、叶Cd含量与Ca含量均呈线性负相关.

Application of base cations to regulate Cd absorption and accumulation in rice

Content of soil base cation (BC) was one of the important factors affecting soil fertility and soil Cd bioavailability. To investigate the effects of BC on migration,transport,and accumulation of soil Cd in rice field system,a pot experiment was conducted with two simulated Cd-contaminated soils (L:0.5 mg·kg^-1; M:1.5 mg·kg^-1). Based on the mole ratios of different soil base cations, BC solutions were prepared using KCl, CaCl₂, NaCl and MgCl₂, and were added to the two simulated Cd-contaminated soils. Rice was then planted. The results indicated that applying BC to the soils resulted in an increase in soil CEC values. In the low and moderate Cd-contaminated soils, soil exchangeable Cd contents extracted with CaCl₂ decreased by 24.6%~56.1% and 17.0%~71.1%, respectively,and Cd contents in brown rice decreased by 9.1%~60.5% and 7.2%~36.0%, respectively. There were positive correlations between Cd contents in brown rice and exchangeable Cd contents extracted with CaCl₂ in the two soils. A negative correlation was observed between contents of Cd and Ca in rice roots,stems,and leaves.