田间水肥管理措施及石灰施用对水稻Cd As积累的影响

通过水肥管理及石灰施用等农艺措施阻控水稻Cd、As的积累被认为是经济、易行和有效的措施,但相关措施仍缺乏大田的验证和优化。为此,本研究在湖南省开展了多年多点水肥及石灰施用等农艺阻控对水稻Cd、As积累影响的田间试验。2014—2016年,连续3年在攸县和湘潭研究了常规灌溉、开花后淹水和全生育期淹水3种管理模式对水稻Cd、As积累的影响。结果均表明淹水能显著降低糙米的Cd浓度,但提高了As浓度,后期淹水和全淹水分别使糙米中的Cd浓度降低了15%~30%和26%~45%,但使As浓度提高了6%~25%和11%~65%。2016—2017年,连续两年在湘潭研究了秸秆、硅肥、硫肥和锰肥及其与石灰联用对水稻Cd、As积累的影响。结果表明硅肥和硫肥对水稻Cd、As积累的阻控效果不稳定,大田条件下单独施硅肥难以达到显著降低糙米中Cd、As浓度的效果,施用高剂量(2250 kg·hm-2)的硫肥能显著降低糙米中As浓度。施用生石灰(1500 kg·hm-2)对糙米Cd浓度没有产生显著影响,但施用Ca CO3(12 000 kg·hm-2)能显著降低糙米和秸秆的Cd浓度,甬优538的糙米Cd浓度降低了54%,可见,施用足够量的Ca CO3是阻控水稻Cd积累的有效措施。该研究的结果表明合理的水肥管理措施能降低水稻Cd、As的积累,施用Ca CO3将土壤p H上调至6.5左右是阻控水稻Cd积累的有效措施。

Effects of water management and fertilizer application on cadmium and arsenic accumulation in rice plants under filed condition

Rice contamination with cadmium(Cd) and/or arsenic(As) is an important environmental issue in South China, which seriously threatens the food safe and people health. Water management,fertilizer application and liming are considered to be economic, feasible and effective strategies for reducing Cd and As accumulation in rice grains, however, this still need to proved under filed condition. This study conducted a series of field trials in Hunan Province to investigate the effects of water management, fertilizer application and liming on Cd and As accumulation in rice plants. From year 2014 to 2016, the effects of three kinds of water managements on the accumulation of Cd and As in rice plants were conducted in Youxian and Xiangtan counties, including normal irrigation, flooding after flowering and flooding in full growth period. The results showed that flooding significantly reduced Cd concentration in brown rice, but increased As concentration. Comparing with normal irrigation, flooding after flowering and flooding in full growth period reduced Cd concentration in brown rice by 15%~30% and 26%~45%, but increased As concentration by 6%~25% and 11%~65%. From year 2016 to 2017, the effects of application of rice straw, silicon, sulfur or manganese, and their combing with lime on Cd and As accumulation in rice plants were studied in Xiangtan County. The results showed that the reduction of Cd and As accumulation by silicon and sulfur application was not stable, there are large variation between replications. Result suggested that, under field conditions, it was difficult to significantly reduce Cd and As in brown rice by single silicon application like in pot experiments. High dose of sulfur application(2250 kg·hm^-2) could significantly reduce the As concentration in brown rice. The application of CaO(1500 kg·hm^-2) had no significant effect on Cd concentration in brown rice. However, the application of CaCO₃ (12 000 kg·hm^-2) could significantly reduce Cd concentration of brown rice and straw, which decreased Cd concentration in the brown rice of Yongyou 538 by 54%. Thus, the application of CaCO₃ with adequate amount could be an effective strategy for reducing Cd accumulation in rice grain. The results of this study demonstrated that appropriate water management and fertilizer application will significantly reduce As and Cd accumulation in rice grains. This study will provide practical guidance for optimizing the strategies of water and fertilizer managements for reducing Cd and As accumulation in rice grains.