关键词: 水分管理, Cd污染土壤, 水稻糙米, Cd含量, 保护性耕作, 秸秆还田, 微生物生物量碳, 微生物活性, 土壤呼吸, 呼吸熵

Abstract: 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⁺.

Key words: water management, Cd polluted soil, brown rice, Cd content, conservation tillage, straw recycling, microbial biomass C, microbial activity, soil respiration, respiratory quotient.