硅对水稻镉转运的抑制效应研究

Inhibitory Effect of Silicon on Cadmium Accumulation and Transportation in Rice

为探究外源施加硅肥对水稻(Oryza sativa L.)镉积累和转运过程的抑制效应,采用盆栽试验的方法,以广西普遍种植水稻品种"中广香1号"为研究对象,在0、400、600和800 mg·kg^(-1) 4个硅肥(Na2Si O3)处理水平下,研究了不同硅肥施加量对水稻镉吸收转运及产量结构的影响。研究结果显示,糙米镉含量随硅肥用量的增加而显著下降(P<0.05)。当硅肥用量为800 mg·kg^(-1)时,糙米镉含量最低,为0.39 mg·kg^(-1),相比对照(未施硅肥)减少了32.76%。与对照相比,施用硅肥可以提高土壤p H,且土壤有效态镉的含量随着施硅量的增加而显著降低,当施硅量为800 mg·kg^(-1)时,土壤中有效态镉含量显著低于未施硅处理,降幅达10.57%。研究发现硅肥抑制糙米积累镉与硅阻碍镉在水稻各部位的转运有关,土壤施硅促进水稻根表铁膜的形成,加强铁膜对镉的吸附作用,显著地降低镉从根系铁膜向根部和镉从根部向茎秆的转运(P<0.05);随着硅肥施加量的增加,茎秆对镉的截留效果更显著,当硅肥用量为800 mg·kg^(-1)时,镉从根系铁膜向根部和镉从根部向茎秆的转运因子分别较对照下降了10.34%和15.79%。此外,硅肥处理下水稻产量明显高于对照,且结实率显著增加。因此,硅肥可作为降低水稻镉积累的有效农艺措施。

The experimental objective is to investigate the inhibitory effect of silicon application on Cd accumulation and transportation in rice using pot experiments. A common-accumulating rice cultivar (Zhongguangxiang I) in Guangxi was selected at pot experiments. Silicon fertilizer (as Na2SiO3) was applied to soil at four levels of 0, 400, 600 and 800 mg·kg-1. The results showed that Cd concentration in brown rice decreased with the increase of silicon application rate. The lowest Cd concentration in brown rice(0.39 mg·kg-1) was found at 800 mg·kg-1 silicon treatment, which was decreased by 32.76% compared with the control. The reductionof Cd availability induced by an increase in soil pH. Besides silicon-induced enhancement of the formation of iron plaque on the rootsurface of rice may be significant to reducing Cd accumulation in rice., and the inhibitory effect of Si on Cd accumulation in brownrice may be due to the fact that Si application decreased Cd transportation from iron plaque to root and from root to stem. The transport factors of Cd from iron plaque to root and from root to stem decreased by 10.34% and 15.79% at 800 mg·kg-1 silicontreatment, respectively. Moreover, silicon fertilization slightly increased the production of rice. The seed setting rate of rice with 600 and 800 mg·kg-1 silicon treatment was significantly higher than that without silicon treatment (P<0.05). These findings indicate that silicon fertilization is a feasible method to fix Cd in the shoot or root to decrease the Cd accumulation in rice.