调理剂及农艺措施对污染稻田中水稻吸收镉的影响

【目的】探究水分管理、调理剂措施和组合措施对污染稻田稻米降Cd效果,旨在探索出不显著降低水稻产量前提下,能更高效降低土壤Cd生物有效性和稻米中Cd含量的方法。【方法】在湖南省株洲市选择中度Cd污染稻田开展田间小区水稻试验。试验中水稻种植两季,早稻品种为中嘉早17,晚稻为泰优390。试验分为6组,分别为水分管理（T2）处理、施用硅肥（T3）处理、施用竹炭处理（T4）、施用硅肥结合水分管理（T5）处理、施用竹炭结合水分管理（T6）处理和1个试验对照（T1）,重复3次。【结果】试验各处理对稻田土壤有效态Cd含量均有降低,竹炭结合水分管理（T6）处理对两季水稻土壤均有显著降低,硅肥结合水分管理（T5）处理对晚稻土壤有效态Cd降低幅度最大。试验各处理对水稻各部位Cd含量均有降低效果,在糙米Cd含量方面,5个试验处理中对糙米Cd含量降低幅度以组合措施修复技术效果最好,即硅肥结合水分管理（T5）和竹炭结合水分管理（T6）处理。在水分管理修复技术(T2)中降Cd效果最高为29.23%;在施用调理剂修复技术中,硅肥处理（T3）和竹炭处理（T4）对稻壳和糙米中Cd含量均有显著降低（P＜0.05）作用,其中硅肥处理（T3）糙米最高降Cd幅度为49.23%,竹炭处理（T4）糙米最高降Cd幅度为47.69%;在组合措施中均能显著降低水稻糙米Cd含量,其中硅肥结合水分管理（T5）处理糙米降Cd幅度为60.34%—78.46%,竹炭结合水分管理（T6）糙米降Cd幅度为56.90%—67.69%。同时,本文对土壤有效态Cd含量与水稻各部位Cd含量相关性进行分析,发现水稻籽粒（稻壳与糙米）中Cd含量与土壤有效态Cd含量存在极显著正相关（P＜0.01）,且两个水稻品种规律一致。各处理对水稻各部位富集系数亦有降低效果,以硅肥结合水分管理（T5）处理和竹炭结合水分管理（T6）效果最好。对于水稻各部位向籽粒转运系数降低效果各部位规律不一致,但茎鞘和叶片两个部位向籽粒（稻壳和糙米）转运系数均显著降低,水分管理（T2）处理除外。在水稻产量方面,仅水分管理（T2）处理对中嘉早17有显著降低,其他处理降低幅度不显著,各处理对泰优390处理没有显著影响。【结论】组合措施优于单一水分管理或单一调理剂处理,且在水稻产量没有显著降低情况下对稻米Cd污染稻田稻米降Cd幅度最高达到78.46%,可以进一步确保Cd污染农田安全利用。

Effects of Conditioning Agents and Agronomic Measures on Cadmium Uptake by Rice in Polluted Rice Fields

【Objective】How to safely use cadmium (Cd) to prevent it from contaminating cultivated land to produce up to standard rice is a hot topic for scholars. This paper mainly explored the effects of water management, conditioning agent measures and combined measures on the Cd reduction of rice in polluted rice fields. It aimed to reduce the bioavailability of soil Cd and the Cd content in rice under the premise of not significantly reducing rice yield【Method】Field rice experiments were carried out in a moderately Cd-contaminated paddy field in Zhuzhou City, Hunan Province, through a field plot test. In the experiment, rice was planted for two seasons. The early rice variety was Zhongjiazao17, and the late rice variety was Taiyou390. The test setup design was divided into 6 groups, namely water management treatment (T2), application of silicon fertilizer treatment (T3), application of bamboo charcoal treatment (T4), application of silicon fertilizer combined with water management treatment (T5), application of bamboo charcoal combined with water management treatment (T6), and control (T1), and each treatment was repeated 3 times.【Result】The effective Cd content in the paddy soil was reduced by the treatments. The bamboo charcoal combined with water management treatment (T6) significantly reduced the soil moisture in the two rice grow seasons. The silicon fertilizer combined with water management treatment (T5) had the largest reduction of available cadmium in the late rice soil. The treatments all had the effect of reducing the Cd content in all parts of rice. In the aspect of cadmium content of brown rice, the reduction of Cd content in brown rice in the five experimental treatments was the best in combination with the repair technology, namely silicon fertilizer combined with water management treatment (T5). Combined with carbon and water management (T6), in the water management and repair technology, the water management in the whole growth period has the best Cd effect, the highest reduction was 29.23%; in the application of conditioning agent repair technology, silicon fertilizer treatment (T3) and bamboo charcoal treatment (T4) significantly reduced rice husks and brown rice (P＜0.05). Under the silicon fertilizer treatment (T3), brown rice had the highest Cd amplitude of 49.23%; under the bamboo charcoal treatment (T4), brown rice had the highest Cd amplitude of 47.69%. In the treatment technology, the Cd content of rice brown rice could be significantly reduced. The silicon fertilizer combined with water management treatment (T5) of brown rice decreased Cd range from 60.34% to 78.46%, and bamboo charcoal combined with water management (T6) brown rice decreased Cd range from 56.90% to 67.69%. At the same time, this paper analyzed the correlation between soil available cadmium content and cadmium content in various parts of rice, and found that there was very significant positive correlation between rice grain (rice husk and brown rice) and soil available cadmium content (P＜0.01), and two rice varieties were consistent. The treatments also had the effect of reducing the enrichment coefficient of various parts of rice, and the best results were obtained by silicon fertilizer combined with water management treatment (T5) and carbon combined water management (T6). Regarding the effect of reducing the rice-to-grain transfer coefficients from different parts of the rice, the rules were inconsistent, but the transfer coefficients of the stalk sheaths and leaves to the grains (rice hulls and brown rice) were significantly reduced, except for water management (T2) treatment. In terms of rice yield, only water management treatment (T2) significantly reduced yield of Zhongjiazao17, and the other treatments did not decrease significantly. Each treatment had no significant effect on Taiyou390.【Conclusion】The combination measures were better than single water management or single conditioner treatment, and the maximum Cd drop in rice Cd-contaminated rice fields reached 78.46% when rice yield was not significantly reduced, which could further ensure the safe use of Cd-contaminated farmland.