外源锌对水稻各部位镉吸收与累积的拮抗效应

Antagonistic effects of exogenous zinc on uptake and accumulation of cadmium in various rice organs

为探明外源锌(Zn)对镉(Cd)污染稻田系统Cd吸收累积的影响,采用盆栽试验,向轻度(Cd含量为0.50 mg·kg^(-1))和中度(Cd含量为1.50 mg·kg^(-1))Cd污染土壤中施用不同浓度的外源Zn,研究Zn对土壤、水稻根表铁膜和水稻各部位中Cd、Zn含量变化的影响,探讨外源Zn对Cd污染稻田系统Cd吸收累积的交互作用.结果表明,在2种Cd污染土壤中,施用外源Zn显著降低了湘晚籼12糙米Cd含量,降低幅度为13.4%～78.4%;在轻度Cd污染土壤中,施用外源Zn显著降低了威优46糙米Cd含量,降低幅度为14.7%～79.8%,而在中度Cd污染土壤中,当外源Zn浓度超过40 mg·kg^(-1)将增加威优46糙米Cd含量;在2种Cd污染土壤下均显著增加2种水稻根表铁膜数量,分别增加14.7%～85.9%、5.8%～61.2%;但对土壤交换态Cd含量无显著影响.在2种Cd污染土壤中,2种水稻各部位Cd/Zn比值与Cd含量正线性相关,且各部位Cd/Zn比值呈下降趋势,2种水稻糙米、茎叶间Cd-Zn拮抗作用显著.轻度Cd污染土壤中,施加外源Zn可以降低湘晚籼12和威优46糙米中的Cd含量;中度Cd污染土壤中,外源Zn仍然可以降低湘晚籼12糙米Cd含量,而当外源Zn施加量高于40 mg·kg^(-1)时将增加威优46糙米的Cd含量.

A pot experiment was performed to verify the effects of exogenous zinc (Zn) on uptake and accumulation of cadmium (Cd)in various rice organs,to study the changes of contents of Cd and Zn in soils,iron plaque,and various rice organs due to exogenous Zn,and to explore the interaction of Zn and Cd in rice paddy systems.Two rice cultivars Xiangwanxian 12 and Weiyou 46 and two Cd-polluted soils with Cd contents of 0.50mg·kg^-1 and 1.50 mg·kg^-1 were used for the pot experiment.The results showed that application of exogenous Zn significantly decreased Cd contents in brown rice of Xiangwanxian 12 by 13.4%to 78.4% in the two Cd-polluted soils.Application of exogenous Zn significantly decreased Cd contents in brown rice of Weiyou 46 by 14.7% to 79.8% in the light Cd-polluted soil,but when exogenous Zn exceeded 40mg·kg^-1 in the moderate Cd-polluted soil,Cd contents in brown rice of Weiyou 46 increased.Exogenous Zn also significantly increased amounts of iron plaque in Xiangwanxian 12 and Weiyou 46 by 14.7%to 85.9% and 5.8%to 61.2% in the two Cd-polluted soils,respectively,but no apparent effects on exchangeable Cd contents in soil were observed. Correlation analysis showed that positive correlations were found between ratios of Cd/Zn and Cd contents in various rice tissues,and ratios of Cd/Zn in rice various tissues decreased with application of exogenous Zn in the two Cd-polluted soils.It was obvious that there was a significant antagonistic effect between Cd and Zn in brown rice,stems and leaves of two rice cultivars.Application of exogenous Zn decreased Cd contents in brown rice of Xiangwanxian 12 and Weiyou 46 in the light Cd-polluted soil.In the moderate Cd-polluted soil,exogenous Zn could decrease Cd contents in brown rice of Xiangwanxian 12,but Cd contents in brown rice of Weiyou 46 increased when exogenous Zn exceeded 40mg·kg^-1.