生物炭对油菜吸收镉的阻控效应及其机理研究

Large areas of agricultural fields have been contaminated by heavy metals, especially Cadmium(Cd), in China. Many studies have shown that oilseed rape is capable of accumulating relatively high levels of Cadmium from heavy metal contaminated soils. Biochar production via pyrolysis of crop residues and its application to soil has been proposed as a novel approach to immobilize soil heavy metals and reduce their accumulation in crops. A growing body of evidence shows that biochar does affect crop growth and accumulation of heavy metals. However, the processes and mechanisms behind these influences remain unclear. With regard to the mechanisms operating, different processes have been proposed to explain the modifications of the soil properties after biochar inputs. These mechanisms are all related to the soil properties, but the link to the plants, i.e., through a systematic study of the impacts of plant growth on biochar properties, remains largely unexplained. Studies about the impacts of root system on biochar properties are rather scarce.. This study will evaluate the effects of biochar amendment on control Cd accumulation of oilseed rape ( Brassica napus) from Cd contaminated soils. Biochar will be produced from rice straw by heating at 400℃. In order to study the impacts of biochar amendment on the growth and Cd accumulation of B. napus, field experiments will be conducted in three sites with rice paddy soils contaminated by Cd. The concentrations of Cd in these soils are 0.18, 0.63, 1.23mg/kg. Biochar will be applied only once at rates of 0, 4, 8, 16g/kg before planting of B. napus using direct-seeding.Pot culture experiments will be conducted to study the impacts of B. napus growth on biochar properties and stabilities of Cd adsorbed by biochar. Comparative study will be conducted to investigate the influence of B. napus roots on biochar with Cd and without Cd in a pot experiment. The influence of B. napus root exudations on properties of biochar with Cd will be investigated. One pot experiment will be carried out to study the effects of roots of B. napus on the biochar absorption capacity for Cd.. Changes of properties of biochar and soil will be analyzed. Meanwhile, the growth and Cd accumulation of B. napus will be measured. The component of root exudations will also be analyzed. Through these analysis, the impacts of biochar on the growth and Cd accumulation of B. napus will be assessed in greater detail. The processes and mechanisms related to biochar controlling the growth and Cd accumulation of B. napus will be discussed.

我国耕地镉污染严重，油菜易吸收镉。大量研究证实生物炭影响作物生长与吸收重金属，有关过程与机理还没有全面研究清楚，已有的研究主要从生物炭改变土壤特性与生物炭直接提供养分方面解析有关过程与机理，从作物生长影响生物炭特性角度解析有关过程与机理的研究缺乏。利用生物炭阻控油菜吸收镉的研究少。项目以甘蓝型油菜和生物炭为材料，采用田间试验研究生物炭阻控油菜吸收镉的差异性，采用砂培试验研究油菜生长对生物炭特性及其吸持镉稳定性的影响；综合分析生物炭、土壤和油菜之间的相互作用，解析生物炭调控油菜生长与吸收镉的效应，确定生物炭阻控油菜吸收镉的最优效应及生物炭最佳添加剂量，确定改变生物炭特性及其吸持镉稳定性的油菜根系分泌物成分，从根系影响生物炭特性角度揭示生物炭影响油菜生长与吸收镉的过程与机理。研究结果可为在镉污染耕地上油菜的安全生产提供科学依据。

我国耕地镉污染严重，油菜易吸收镉。利用生物炭阻控油菜吸收镉的研究少。本项目针对阻控油菜吸收镉和促进油菜生长的问题，项目以甘蓝型油菜和生物炭为材料，采用田间试验研究生物炭阻控油菜吸收镉的差异性，采用盆栽试验研究油菜生长对生物炭特性及其吸持镉稳定性的影响；综合分析生物炭、土壤和油菜之间的相互作用，解析生物炭调控油菜生长与吸收镉的效应。在污染稻田中选建试验样地，在样地中生物炭添加量为0、4、8和16g/kg。主要结果及数据如下：（1）在炭化温度450和550℃下用稻草秸秆作原料制备了生物炭；两种生物炭吸持镉的量分别为42.15和59.87mg/g。（2）在污染稻田土中添加生物炭可以显著增加油菜生物量与产量；在镉轻度污染稻田和中度污染稻田分别添加生物炭9.60和19.20t/hm2时，减少油菜吸收镉的效果最佳。（3）生物炭增加油菜根系分泌苹果酸与柠檬酸的量，这两种有机酸增加后使生物炭吸持镉的能力增强。（4）玉米秸杆与生物炭联合阻控显著减少了油菜体内的镉含量。（5）采用玉米秸杆-生物炭-生姜联合调控模式可以有效减少镉进入油菜/猕猴桃轮作体系。（6）在镉中度污染水稻土中添加生物炭19.20t/hm2可以显著减少镉进入油菜/水稻轮作体系。（7）筛选确定出芽短梗霉（Aureobasidium pullulans）是一种高耐受镉的菌株。这些成果为在镉中轻度污染稻田中安全栽培油菜提供科学支持。