土壤与大气双重胁迫下苋菜幼苗对铅的累积与生理响应

Accumulation and physiological response of Amaranthus tricolor L. seedlings to lead under soil and atmospheric stress

土壤污染被普遍认为是农作物Pb的主要来源,但是针对大气沉降与土壤对作物胁迫效应的研究相对较少。通过喷洒Pb溶液和Pb污染土壤盆栽试验,模拟研究大气和土壤不同Pb污染源胁迫对苋菜幼苗生长发育和生理生化特征的影响,以及Pb在其体内的累积和化学形态。结果表明,大气和土壤Pb胁迫都能显著提高苋菜幼苗Pb含量,其中土壤影响占62.64%,大气影响占32.89%。不溶性磷酸盐和果胶、蛋白结合态是Pb的主要化学形态。单独大气Pb胁迫促进了苋菜幼苗的生长和可溶性蛋白质的合成,而土壤Pb胁迫则为抑制作用,主要表现为H2O2和MDA含量增加,造成细胞膜系统损伤。抗氧化酶(SOD、POD、CAT)和抗氧化剂(AsA、GSH)对土壤和大气Pb胁迫均表现出积极有效的响应。研究结果可为大气和土壤重金属共同胁迫地区农作物的环境风险评价以及污染防治提供重要的科学依据。

Soil pollution is generally attributed as the main source of Pb in crops. However, there are relatively few studies on the effects of atmospheric deposition and soil stress on crops. In this study, we investigated the influence of Pb due to atmospheric deposition and soil stress on the growth, accumulation, chemical morphology, and physiological and biochemical responses of Amaranthus tricolor L. seedlings using Pb solution spraying and Pb contaminated soil pot experiments. The results indicated that both atmospheric and soil Pb stress can significantly increase the Pb content in the Amaranthus tricolor L. seedlings. Among them, the effect of soil concentration accounted for 62.64%, and the effect of atmospheric deposition accounted for 32.89%. Insoluble phosphate, pectin, and protein-bound state are the primary chemical forms of Pb. The atmospheric Pb stress alone promoted the growth of the Amaranthus tricolor L. seedlings and synthesis of soluble proteins;however, soil Pb stress exhibited an inhibitory effect, increased hydrogen peroxide and malondialdehyde content, and caused damage to the cell membrane system. Antioxidant enzymes(superoxide dismutase, peroxidase, catalase) and antioxidants(ascorbic acid, glutathione) exhibited positive and effective responses to the soil and atmospheric Pb stress. The research results provided an important scientific basis for the environmental risk assessment and pollution prevention of crops in areas under heavy stress from the atmosphere and soil.