滴灌条件下不同价态外源硒对水稻硒吸收及转运的影响

摘要

[目的]通过田间小区试验,研究外源硒酸盐及亚硒酸盐施入滴灌稻田中对土壤中不同价态硒含量及其生物有效性的影响,旨在为滴灌条件下富硒水稻的开发提供理论依据.[方法]以水稻品种T-43为材料,硒肥为亚硒酸盐与硒酸盐,施硒量为0.3、0.6、1.2 kg/hm2.[结果]研究结果表明,施肥后1d硒酸盐1.2 kg/hm2处理土壤中可溶态硒含量最高,比对照高了340%;可交换态硒、铁氧化物态硒及有机态硒含量在施肥后4d亚硒酸盐1.2kg/hm2处理最高,较对照分别提高了380%、56%、59%,硒酸盐处理铁氧化物态硒及有机态硒含量增加不显著,说明硒酸盐主要以可溶态硒存在,而亚硒酸盐主要以可交换态硒存在,并且由可溶态转化为其他形态,因此降低了其有效性.对水稻的根、茎、叶及籽粒硒含量分析后发现,亚硒酸盐处理的籽粒和叶中的硒含量显著低于硒酸盐处理,而其根部硒含量显著大于硒酸盐处理,茎部硒含量无显著差异,且亚硒酸盐处理的根部硒累积量均大于硒酸盐处理.[结论]说明施用亚硒酸盐大部分积累在水稻根部,硒酸盐处理的地上部硒累积量大于亚硒酸盐处理,同时,硒酸盐处理的根系吸收系数、初级转运系数、次级转运系数均大于亚硒酸盐处理,说明亚硒酸盐大部分积累在水稻根部且向地上部转运较难,硒酸盐随水滴施的生物有效性高于亚硒酸盐.%[Objective]To lay a theoretical base for the development of selenium-enriched rice,a field plot experiment was performed to study the effects of selenate and selenite on selenium transformation and bioavailability under drip irrigation.[Method]The experiment consisted of two factors:(i)amount of Se fertilizer (0.3,0.6,and 1 .2 kg/hm2 ), (ii)type of Se fertilizer (selenate and selenite).[Result]The results indicated that selenate application at the level of 12 kg/hm2 resulted in the highest soluble selenium concentration one day after fertilization (340% higher than control),1 .2 kg/hm2 selenite application resulted in the highest exchangeable selenium,Fe oxide-bound selenium and organic matter-bound selenium concentrations four days after fertilization (380%,56%,59% higher than control).It could be seen that selenate mainly existed in soluble form in soil,while selenite could be transformed from the soluble form to other three forms,which decreased its bioavailability.We found that under selenite treatment selenium concentration in leaves and seeds was significantly lower than that under selenate treatment.However,under selenite treatment,the selenium content in root was significantly higher than that under selenate treatment.[Conclusion]The selenium accumulations in shoot and root of rice were significantly higher under selenate treatments than those under the selenite treatments.Compared with the selenate treatment, absorption index, primary transport index and secondary transport index were lower in the selenite treatment.In conclusion,selenite has higher bioavailability than selenite in drip irrigation.