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为了保证镉含量处于临界值附近土壤上农产品的安全生产,避免不合理施肥引起土壤镉的活化和增加作物吸镉量,研究了4种主要氮肥对不同生育期小麦吸收镉的影响.研究表明,施用硫酸铵、硝酸铵和尿素都比氯化铵促进了小麦生长,明显提高了小麦籽粒产量.所有氮肥处理都比无肥处理增加了小麦对镉的吸收,但不同氮肥处理之间的效果差异显著,其中以氯化铵的促进作用最强,硫酸铵处理的小麦吸收镉最少,尿素处理的小麦对镉的吸收随其用量增加而增加.在小麦整个生育期中,生育前期吸收镉较少,中、后期明显增大;但植株体内镉的浓度却表现为前期高、后期低,呈现随生育期递进而逐渐降低的趋势,只有氯化铵处理表现为拔节期体内镉含量为最高.镉在小麦体内的累积与其生物量的增加呈正相关,从秸秆向籽粒转移的总镉量随小麦籽粒/秸秆比的增加而降低.本试验中土壤的镉含量小于土壤环境质量污染二级标准,但籽粒含镉量均超过国家食品卫生标准允许量(0.1mgkg-1),表明土壤镉污染指标与作物品种密切相关.在镉污染土壤上,应选用低富集镉的小麦品种,避免使用氯化铵,防止过量施用尿素或其它铵态氮肥.
In order to ensure the safe production of agricultural products in the soil near the critical value and to prevent the activation of cadmium in the soil caused by irrational fertilization and to increase the cadmium uptake by crops, the effects of four main nitrogen fertilizers on cadmium uptake in different growth stages were studied. The application of ammonium sulfate, ammonium nitrate and urea promoted the growth of wheat and significantly increased the grain yield of wheat compared with ammonium chloride.All the nitrogen treatments increased the Cd uptake by wheat compared to the no-fertilizer treatment, but the differences in the effects of different nitrogen treatments Significantly, ammonium chloride promoted the strongest, ammonium sulfate-treated wheat had the least absorption of cadmium, and the absorption of cadmium by urea-treated wheat increased with the increase of its dosage.In the whole wheat growth period, But significantly increased in late stage, but the concentration of cadmium in plants showed a high level in the early stage and a low stage in the late stage, and showed a tendency of decreasing gradually with the progress of growth stage. Only the ammonium chloride showed the highest level of cadmium in the jointing stage The accumulation in wheat was positively correlated with the increase of biomass, and the total amount of cadmium transferred from straw to grain decreased with the increase of wheat grain-straw ratio. The content of cadmium in soils was less than Grade II standard of soil environmental quality, but the content of cadmium in grains exceeded the allowable level of national food hygiene standard (0.1mgkg-1), indicating that soil cadmium pollution index is closely related to crop varieties. , Low cadmium-enriched wheat varieties should be selected to avoid the use of ammonium chloride to prevent over-application of urea or other ammonium nitrogen fertilizer.