镉污染农田不同水稻品种镉积累差异研究

为降低稻米Cd含量,筛选适用于粮食安全生产的Cd低积累水稻品种,利用8个早稻品种和10个晚稻品种进行Cd低积累水稻品种筛选田间小区试验,对比不同品种水稻糙米及其他部位的Cd含量,并分析不同品种水稻的生长发育及产量状况。结果显示:不同品种水稻间根际土pH值和根际土有效态Cd含量均有显著差异,且两者和水稻Cd含量的相关性较高,根际土pH值降低和有效态Cd含量升高会导致了水稻Cd含量升高;综合考虑降Cd效果和产量状况,供试的18个水稻品种中,早稻中嘉早17、株两优189、华1s/R039三个品种和晚稻长两优772、长两优1419、长两优051三个品种推荐为湖南地区中低Cd污染农田适宜推广的Cd低积累水稻品种,且早稻品种株两优189糙米Cd含量仅有0.09 mg·kg-1,晚稻品种长两优772和长两优051也仅有0.085 mg·kg-1左右,Cd低积累特性明显。研究表明,利用不同水稻品种对Cd的积累特性差异,可以筛选出适于中低Cd污染稻田的低累积型水稻品种,使稻米Cd含量降至国家粮食安全限量标准。

Cadmium accumulation in different rice cultivars from cadmium-polluted paddy fields

In this study, rice cultivars that accumulated low levels of Cd were selected to reduce Cd content in rice and ensure the security of food production. The physiological growth and yield of 8 early-and 10 late-cultivars were studied to find those with low Cd accumulation and compare their differences based on a paddy field plot experiment. The results showed significant differences in pH value and available Cd content in the rhizosphere of the different cultivars. In addition, there were significant correlations among the pH values, available Cd content in rhizosphere, and the Cd content in rice. This demonstrated that a decrease in rhizosphere pH and an increase in available Cd content resulted in an increase in Cd content in rice. Based on the Cd content and rice yield, some rice cultivars were recommended as low Cd accumulation cultivars for fields moderately to slightly contaminated with Cd, including early cultivars ZJZ17, ZLY189, and H1s/R039 and late cultivars CLY772, CLY1419, and CLY051. Of these, the Cd content in the brown rice of early-cultivar ZLY189 was 0.09 mg·kg^-1 and that in the late-cultivars CLY772 and CLY051 was approximately 0.085 mg·kg^-1, which are both lower than the maximum allowable levels of Cd in food in China (0.2 mg·kg^-1). This study thus showed that it is practical to select rice cultivars that accumulated low levels of Cd and are adapted to moderately to slightly Cd-contaminated paddy fields based on the differences in the Cd accumulation characteristics of the former. This provides a basis for food production on farmland contaminated with heavy metals.