工业大麻耐Pb响应机制及对矿区Pb污染农田的修复潜力研究

Lead (Pb), one of heavy metal elements, is seriously polluting field soil in Yunnan mining area and has threatened the local food safety and health of residents. Earlier research indicated that industrial hemp has excellent tolerance and accumulation ability of Pb. However, its resistance mechanism of Pb and ability of remediating Pb contaminated soil have not been studied deeply. In this project, one industrial hemp variety, Yunma 1, was selected to carry out pot experiments under high Pb stress (2000mg•kg-1) and field trials for its large biomass and accumulation ability of Pb. By pot experiments, industrial hemp roots and leaves in seedling period will be sampled for analysis of complex response of organic acids, chemical forms and cellular compartmentation of Pb，antioxidative enzymes activity of its leaves，etc. It will further reveal Pb tolerance mechanism of industrial hemp. Meanwhile, field trials will be carried out by planting Yunma 1 and rotating corn in the field polluted seriously by Pb (> 2000mg•kg-1) in the mining area. The accumulated Pb content of industrial hemp plants will be detected at the stage of fiber maturation. The reduction degree of Pb content in corn seed could be analyzed to evaluate the ability of industrial hemp to remediate Pb contaminated field in mining area. Acquired tolerance mechanism and remediation data of industrial hemp could provide theory evidence for solving the problem of food security caused by Pb pollution in mining area.

铅（Pb）是云南矿区污染最严重的一种重金属，已严重威胁当地粮食安全和居民健康。前期研究表明工业大麻是耐受和富集Pb的优良作物之一，但尚未对其耐Pb机制和对Pb污染土壤的修复能力开展深入研究。本项目拟以生物量大、富集Pb能力强的工业大麻品种“云麻1号”为研究对象，通过高Pb（2000mg·kg-1）盆栽胁迫试验，研究苗期根和叶中有机酸的络合响应、Pb的化学形态分布、细胞区隔化作用以及叶片抗氧化酶活性调节等，揭示工业大麻对Pb的耐性机制。同时，在矿区Pb污染严重地块(Pb＞2000mg·kg-1）种植工业大麻，并在修复的地块上种植玉米，在纤维成熟期测定工业大麻中的Pb吸附总量及玉米籽粒中Pb含量，分析玉米籽粒中Pb含量的降低程度，评价大麻对矿区Pb污染的修复能力，为解决矿区农田因Pb污染而导致的粮食安全问题提供理论依据。

针对矿区重金属铅（Pb）污染严重问题，本项目拟以生物量大、富集Pb能力强的工业大麻品种“云麻1号”为研究对象，通过高Pb（2000mg/kg）胁迫的生理生化响应机制与矿区 Pb污染严重地块进行修复验证相结合，揭示工业大麻耐Pb机制和对Pb污染土壤的修复潜力。研究结果如下：（1）单一的Pb胁迫下，Pb主要积累在根中，种子中含量较低；高浓度的多种重金属交互胁迫下，种植年限影响不同器官的Pb积累，第1年的Pb主要积累在根中，随着种植年限的延长，种子中的含量升高，种子中的Pb超过50mg/kg。（2）Pb在5000mg/kg范围内，虽云麻1号不同真叶期叶的MDA升高，膜脂过氧化程度加剧，但POD、CAT、SOD、GSH-Px等的抗氧化能力很强，同时Pro也能维持细胞稳定性和抵抗胁迫造成的植物毒害。（3）细胞壁、叶绿体和液泡都是Pb的重要储存位点，在较小细胞器的Pb含量均较低，这说明即使高Pb胁迫也不影响细胞器的基本功能和大麻植株的正常生长。（4）2017年Pb胁迫试验下，工业大麻叶中的Pb主要以活性高对作物伤害最大的乙醇提取态和去离子水提取态存在，这两种提取态占各化学形态总和的46%~60%。但在2018年试验中，叶中Pb均主要以活性低对作物伤害最小的HCl提取态存在，占各化学形态总和的30%~50%。（5）在不同浓度的Pb胁迫下，云麻1号根际主要分泌不同含量的草酸和柠檬酸来改变根际环境，促进植物对Pb吸收。（6）在矿区大田多种重金属交互作用下，两种作物均正常生长。Pb主要积累在云麻1号的根、叶和纤维中。用工业大麻修复不同年限后，玉米籽粒中Pb、Cu、Cd、As含量不断降低，玉米籽粒中的Pb含量每年依次减少1mg/kg，修复2年后，种子中的Zn和Cd含量未超过食品污染物限量标准。用工业大麻修复重金属污染土壤，可有效降低复种作物多种重金属含量。