夜间增温对小麦吸持铅素的影响

Effects of Night Warming on Pb Retention of Wheat

当前非对称气候变暖及部分农业土壤铅富集潜在影响我国小麦生产,揭示夜间增温对小麦吸持铅素及其分配的影响有助于确保粮食安全生产。利用田间被动式夜间增温系统设置不同铅浓度客土盆栽试验,研究小麦产量与地上部组织的生物量、铅含量与积累量、铅富集系数和迁移系数随温度变化的响应。结果表明,夜间增温显著增加小麦产量8.3%,却显著降低茎叶和地上部总干重;铅污染表现为负效应且随污染程度增加而加大。夜间增温显著降低地上部植株、籽粒与颖壳中铅含量,但对茎、叶中铅含量影响不大;分别显著降低籽粒中铅积累量7.6%(轻度污染)和6.8%(重度污染)、颖壳中铅积累量12.0%(无污染)和13.9%(重度污染)和全部污染处理下小麦地上部(14.0%~23.3%)、茎(22.5%~24.9%)、叶(17.9%~31.8%)中铅积累量。夜间增温显著降低无污染处理铅在茎、叶、籽粒和颖壳中的富集系数和轻污染处理铅在茎、籽粒和颖壳中的富集系数,但未显著影响重度污染处理铅在各器官中的富集系统。增温显著降低了全部污染处理中由茎向籽粒、颖壳转移的铅迁移系数。夜间增温有利于小麦生产且能降低铅胁迫农田粮食遭受铅污染的潜在风险。

【Objective】Grain production in China is now subjected to the stresses of climate warming and soil contamination. Therefore,it is vital to understand effects of the dual pressures on growth and production of crops. Climate warming exhibits the characteristic of asymmetric warming that highly increases the temperature at night and in the spring and winter seasons. The asymmetric warming basically overlaps with the growth period of wheat（Triticum aestivum）,a grain crop widely planted in China and the world,to feed around one fifth of the world＇s population. Obviously,asymmetric climate warming has a great potential impact on wheat production. As one of the main heavy metal pollution elements in soil,lead（Pb）has some detrimental effects on growth,development,yield formation and quality of the corp. With the rapid development of industries and increasing human activities,the risk of Pb pollution in some agriculture regions has become more and more prominent,which is deleterious to sustainable development of agriculture and safety production of grains. Since asymmetric climate warming and soil Pb accumulation potentially affects the production of wheat in China,it is very important to analyze the effects of night warming on uptake and distribution of Pb in wheat under the stress of Pb pollution,so as to provide some scientific information essential to ensure safety production of wheat grain in the future harassed by climate change and heavy metal pollution.【Method】 A pot experiment was carried out during the wheat growth season of 2013—2014 in the Zhoushan Experimental Farm of the Henan University of Science and Technology（34°38′N,112°22′E）,which is rainfed and hilly agriculture area with annual average temperature of 13.7 ℃ and annual average rainfall of 650.2 mm. The experiment was designed to have two treatments for temperature,CK and night warming under a passive night warming system,and three levels of Pb pollution（36.8 mg kg^-1,153.4 mg kg^-1 and 415.7 mg kg^-1）. The Pb polluted soils in the pots were collected from the topsoil（0-20 cm）layer of farmlands near the Pb mining and smeltery and the same in physic-chemical and al properties and fertilization（moderate level）but different in Pb content. Responses of the crop（vs. Zhongmai 175）in yield,biomass of different aboveground tissues,and content,accumulation,bioaccumulation coefficient and translocation coefficient of Pb in aboveground tissues to night warming and Pb contamination were investigated. 【Result】Results show that night warming significantly increased yield of the crop by 8.3% and significantly decreased biomass of its aboveground tissues,stem and leaf. Negative effects of Pb pollution on yield and biomass of the crop intensified with increasing level of the pollution. Night warming significantly decreased Pb contents in shoot,grain and glumes,but not in stem and leaf. Night warming significantly decreased Pb accumulation by 7.6% and 6.8 % in grain in the treatments low and high in Pb pollution level,respectively,by 12.0% and 13.9% in glume in CK（no pollution）and the treatments high in Pb pollution level,and by 14.0%-23.3%,22.5%-24.9% and 17.9%-31.8% in shoot,stems and leaves in CK and the treatments high and low in Problem pollution,respectively. Night warming significantly decreased Pb bioaccumulation coefficient in stem,leaves,grain and glumes in CK and in stem,grain and glumes in the treatments low in Pb pollution level,but not in the treatments high in Pb pollution level. Night warming significantly decreased Pb translocation coefficient of Pb from stem to grain and glumes in all the treatments. 【Conclusion】All the findings in this experiment highlight the effects of night warming improving wheat production and lowering the potential detrimental effects of Pb pollution on grain quality of the crop.