叶面施硅对水稻籽实重金属积累的抑制效应

采用盆栽方法,以硅酸钠和正硅酸乙酯为硅源分别配制纳米硅制剂,以水稻(Oryza sativa L.)品种"优优128"为供试植物,在Cd(5mg·kg-1、10mg·kg-1、50mg·kg-1三个水平)、Pb(200mg·kg-1)、Cu(250mg·kg-1)、Zn(300mg·kg-1)复合污染土壤进行种植,在水稻生长期内(苗期、分蘖期、抽穗期)进行叶面喷施纳米硅,研究纳米硅对水稻籽实生长状况及吸收重金属元素的影响,并对两种不同硅源的纳米硅的使用效果进行了比较。结果表明,随Cd污染质量分数增加,水稻百粒质量及单株穗质量均显著降低(P<0.01);Cd、Pb、Zn在籽实中质量分数均增高,而Cu在籽实中质量分数降低。金属元素在籽实中的吸收系数顺序为Cd>Zn>Cu>Pb,表明Cd极易向籽实中迁移。随土壤Cd质量分数增加,水稻籽实中各金属元素的积累量都有所降低。重金属复合污染条件下,叶面施用两种硅制剂均可以缓解水稻的毒害效应,且和施无机硅相比,施有机硅对水稻重金属毒害的缓解效果更显著。表现为叶面施用硅后,水稻百粒质量及单株穗质量均显著提高(P<0.05);且籽实中Cd、Pb、Cu、Zn的吸收量在喷施硅制剂后均显著降低(P<0.05);籽实中重金属元素的吸收系数和积累量均表现出降低的趋势。尤其是随着Cd处理质量分数的增高,施硅对重金属在籽实中积累的抑制效应越显著。这表明叶面施硅在重金属污染的水稻田污染防治中具有应用价值。文章所用的纳米硅制剂,制备简单,对于大面积推广硅肥极为有利。

Effects of leaf application of nanometer silicon to the accumulation of heavy metals in rice grains

A pot experiment was conducted to investigate the effects of leaf application of Si on the accumulation of Cd, Pb, Cu and Zn uptake in rice (Oryza sativa L. cv. youyou 128) grains. The results showed that the weight of per 100 grains, weight of per spike, spike number of rice and the accumulation of Cu in grains were decreased significantly (P<0.01), but the accumulation of Cd, Zn, Pb in the grains increased with the increasing of Cd concentration in the soil. The accumulation factor of heavy metals in grains was in the order: Cd >Zn > Cu > Pb. Leaf application of Si alleviated the toxicity of heavy metals on rice. Compared with leaf application of inorganic Si, or- ganic Si was more positive in alleviating heavy metal toxicity. The leaf application of Si increased significantly (P<0.05) the weight of per 100 grains and weight of per spike, and decreased significantly (P<0.05) accumulation of Cd, Pb, Cu, Zn in the grain, the accumulation factor and the accumulate amount of heavy metals in grains. With the increasing of Cd concentration in soil, the alleviating of Si applica- tion on heavy metal toxicity was more pronounced in the soils contaminated with higher level of Cd. These indicated that leaf application of Si might be an efficient alternative to alleviate heavy metal toxicity and to decrease accumulation of heavy metal in rice grains.