摘要
为了深入探究镉污染稻田土壤施用生石灰降低稻米镉含量的过程机理,采用盆栽试验,分别在水稻插秧前、分蘖期、孕穗期、灌浆期进行生石灰施加处理,水稻成熟后采集植株样品和土壤样品进行相关指标测定。试验结果显示,在水稻不同生育期施加生石灰均可显著提高土壤pH值,降低土壤有效态镉及根系镉含量,同时显著降低糙米镉含量(P<0.05)。分蘖期施加生石灰对糙米镉含量的降低程度最大,其含量比空白对照下降55.2%,显著低于其他处理。在分蘖期施加生石灰后发现,水稻茎秆中的钙含量最高,显著高于其他处理(P<0.05),而其茎秆中的镉含量反而最低,显著低于其他处理(P<0.05)。多变量主成分分析显示,茎秆钙含量与镉含量显著负相关(P<0.05)。综上认为,在水稻分蘖期施用生石灰不仅可以降低土壤有效态镉含量,减少根系对镉的吸收积累,还可以提高水稻茎秆中的钙含量,进而抑制镉由根系向茎秆的转移,表明这两个过程的叠加效应可能是水稻分蘖期施用生石灰降低糙米镉含量的关键因素。
The pot experiment was carried out to further explore the process mechanism that how quicklime applications reduce Cd contents in rice grain cultivated in the Cd-contaminated paddy soils. In the control treatment no quicklime was applied into soil. While in other four treatments, the quicklime was added into soil as lime suspension before the transplanting and at tillering, booting and filling stages, respectively. The plant samples and soil samples were collected after the harvest and then were subjected to analyze aimed indexes. Results showed that soil pH was significantly increased, but available Cd contents in soil and total Cd contents in roots and brown rice were significantly（P〈0.05） decreased after soil was amended with quicklime at different growing stages. However, after the quicklime was applied at tillering stage, the total Cd contents in brown rice was decreased with a maximum reduction that was 55.2% below the control, which was significantly（P〈0.05）lower than other treatments. Meanwhile, the total Ca contents in rice stem-leave was found to be significantly（P〈0.05）higher than others, but the total Cd contents in rice stem-leave was significantly lower than others. Besides, the multivariate principal component analysis showed that Cd content in rice stem-leave was significantly（P〈0.05）negatively correlated with Ca contents. Therefore, the results indicate that applying quicklime at tillering stage not only reduce available Cd contents in soil and decrease Cd absorption and accumulation in root, but also can improve Ca contents in rice stem-leave and then inhibit the Cd translocation from root to stem-leave. The two processes may be key factors reducing Cd contents in the brown rice when quicklime is applied at tillering stage.
出处
《农业环境科学学报》
CAS
CSCD
北大核心
2016年第10期1867-1872,共6页
Journal of Agro-Environment Science
基金
国家科技支撑计划项目(2013BAD15B04
2013BAD03B02)
农业部自由申报项目(2014-S20)
关键词
水稻
生育期
生石灰
稻米
钙
镉
Oryza sativa L.
growing stage
quicklime
rice grain
calcium（Ca）
cadmium（Cd）
