[Effects of the Application of Irrigation Water Containing Zn at the Key Growth Period on the Uptake and Transport of Cd in Rice].

ABSTRACT

In this study， a field experiment was conducted to examine the effects of the application of irrigation water containing Zn at the key growth period （booting stage and filling stage） on exchangeable Cd content in the soil， Cd concentration in pore water， and Cd uptake and transport in rice in a Cd-contaminated paddy field in Liuyang City， Hunan Province. The results indicated that： ① the application of irrigation water containing Zn during the key growth period could inhibit the releasing process of exchangeable Cd from the soil into pore water. Compared with that in the control， the content of exchangeable Cd in soil was slightly changed， but the concentration of Cd in soil pore water at the mature stage was significantly reduced by 16.7%-57.6%. ② The application of irrigation water containing Zn at the key growth period could significantly reduce the Cd content in various parts of rice. Cd contents in root， stem， and brown rice with the application of irrigation water containing 20 mg·L-1 Zn before the booting and the filling stage （BF1） were significantly decreased by 56.0%， 83.8%， and 85.2%， respectively. ③ Compared with the application of 100 mg·L-1 irrigation water containing Zn， the application of 20 mg·L-1 irrigation water containing Zn significantly reduced the uptake and transport of Cd in rice， and the translocation factor （TF） of Cd from rice roots to stems was also significantly reduced by 12.5%-56.3%， with the B1 and BF1 treatments reaching significant levels. These results suggested that the application of irrigation water containing Zn could significantly reduce the uptake and accumulation of Cd in rice， and the application of 20 mg·L-1 irrigation water containing Zn before the booting and filling stage could effectively realize the safe production of Cd-contaminated paddy fields.