镉胁迫条件下淹水时间对水稻吸收累积镉的影响

Effects of Timing and Duration of Waterlogging on Cd Absorption and Accumulation by Rice Under Cadmium Stress

采用盆栽试验方法,以外源添加镉(Cd)模拟土壤镉污染,研究水稻不同生育期(分蘖盛期和灌浆期)淹水以及淹水时间对水稻产量及吸收累积Cd的影响。结果表明,与常规灌溉处理(CI)相比,其他不同淹水时间处理均出现一定程度减产,其中全生育期湿润灌溉(WI)、分蘖盛期开始淹水1~4周(T1、T2、T3和T4)5个处理的水稻产量显著下降,降幅分别为23.7%、16.0%、15.5%、20.2%和18.6%。随着淹水时间的延长,糙米Cd含量呈下降趋势,其中以全生育期淹水处理(WF)的糙米Cd含量最低,仅为WI的3.4%。在相同淹水时间条件下,分蘖盛期开始淹水1~4周处理的糙米Cd含量较灌浆开始淹水1~4周处理(F1、F2、F3和F4)分别降低了27.1%(P<0.05)、46.6%(P<0.05)、56.0%(P<0.05)和35.2%,平均降幅为41.2%。水稻茎叶Cd含量与糙米Cd含量的变化趋势基本相同。水稻茎叶对Cd的转运效率随淹水时间的延长呈下降趋势。不同处理的水稻茎叶和糙米Cd富集系数变异极大,其中WI的糙米、茎叶Cd富集系数分别为WF处理的29.0和18.8倍。淹水能有效抑制水稻对Cd的吸收累积,抑制效果与淹水时间呈正相关,且分蘖盛期淹水对水稻茎叶和糙米Cd累积的抑制效果优于灌浆期淹水。

A pot experiment was conducted using extraneous cadmium as soil Cd contaminant for exploration of effect of timing and duration of waterlogging on rice yield and Cd accumulation in rice. Results show that rice yield lowered to a var-ying extent in all the flooding treatments vs CK （CI）, especially Treatment WI （ wetting irrigation throughout the rice growing season） and Treatments T1, T2, T3 and T4 （ flooding beginning at the prime tillering stage and lasting for 1, 2, 3 and 4 weeks, respectively） , which was 23. 7%, 16. 0 % , 15. 5% , 20. 2% and 18. 6 % , lower, respectively, than CK. Cd content in brown rice decreased with duration of waterlogging, and Treatment WF （ flooded throughout the rice growing sea-son） was the lowest or only 3.4% of Treatment WI in Cd content in brown rice. Under the same waterlogging conditions, Treatment T1, T2, T3 and T4 was 27. 1% （P〈0. 05）, 46. 6% （P〈0. 05）, 56. 0% （P〈0. 05） and 35. 2% lower than Treatment F1, F2, F3 and F4 （flooding beginning at the filling stage and lasting for 1,2,3 and 4 weeks, respectively）, respectively or 41. 2% lower by mean in Cd in brown rice. Cd contents in shoots and brown rice varied along basically simi-lar trends. Cd transport efficiency of the shoots decreased with duration of waterlogging. Cd enrichment factor of shoot andbrown rice differed significantly between treatments and even by 17. 8 and 28. 0 times between Treatments WI and Treat-ments WF. All the findings demonstrate that flooding could effectively inhibit uptake and accumulation of Cd in rice, and the effect is positively related to duration of and timing of flooding, and better with the beginning of flooding at the tilleringstage than at the filling stage.