水分管理模式对水稻吸收累积镉的影响及其作用机理

利用盆栽试验研究了不同水分管理模式(全生育期淹水,WF;分蘖期晒田,TP;乳熟期晒田,MP;分蘖-乳熟期两次晒田,TMP;湿润灌溉,WI)对Cd污染红黄泥和潮泥田水稻吸收累积Cd的影响.结果表明:两种土壤Fe2+含量均以WF处理最高,TMP处理最低;潮泥田和红黄泥WF处理的Fe2+含量分别比TMP增加了585.4%和1316.3%(P0.01).不同处理的两种土壤有效S和有效态Cd含量顺序均表现为:WFTPMPWITMP.其中,潮泥田WF处理的土壤有效S和有效态Cd含量分别比TMP降低了96.4%和70.1%(P0.01),红黄泥分别降低了55.5%和54.1%(P0.01).两种土壤均以WF和MP处理的水稻产量相对较高.不同处理的水稻茎叶、糙米Cd含量顺序为:WFMPTPWITMP;潮泥田WF处理的水稻茎叶和糙米Cd含量分别比TMP降低了74.1%和57.5%(P0.01),红黄泥分别降低了55.6%和43.6%(P0.01).除土壤有效态Cd含量外,不同水分管理模式通过土壤中Fe2+和有效S含量变化对两种Cd污染土壤水稻吸收累积Cd产生显著影响,其中有效S的影响程度显著大于Fe2+.

Effects and action mechanisms of different water management modes on rice Cd absorption and accumulation

Taking Cd polluted reddish yellow paddy soil (RYPS) and alluvial loamy paddy soil (ALPS) as test objects, pot experiments were conducted to study the effects of different water management modes, including whole growth season flooding (WF), draining and sunning field at tillering stage (TP), draining and sunning field at milk stage (MP), draining and sunning field at tillering and milk stages (TMP), and wetting irrigation (WI), on the Cd absorption and accumulation by rice. For the two test soils, their Fe²⁺ content was the highest in treatment WF and the lowest in treatment TMP. Compared with TMP, treatment WF increased the Fe²⁺ content in ALPS by 585.4% and that in RYPS by 1316.3%. The contents of available S and available Cd in the two soils were all in the order of WF<TP<MP<WI<TMP. Comparing with TMP, treatment WF decreased the available S and available Cd contents in ALPS by 96.4% and 70.1% (P<0.01), and those in RYPS by 55.5%  and 54.1% (P<0.01), respectively. On the two soils, WF and MP had a relatively higher rice yield than other treatments. The Cd content in rice stem and leaf and in brown rice followed the sequence of WF<MP<TP<WI<TMP, and was decreased by 74.1%  and 57.5% (P<0.01) in treatment WF on ALPS, and by 55.6%  and 43.6% (P<0.01) in treatment WF on RYPS, respectively, compared with those in treatment TMP. Besides the available Cd content of the two soils, water management modes also played important roles in the Cd absorption and accumulation by rice via affecting the soil Fe²⁺ and available S contents, with the effects being significantly larger on soil available S than on soil Fe²⁺.