两种黑麦草砷吸收特征及其与茎叶营养元素积累的关系研究

Arsenic absorption characteristics and relationships between arsenic absorption and nutrient accumulation in stems and leaves of two ryegrass species under arsenic stress

采用盆栽实验研究了100mg·kg^(-1)砷(As)胁迫下,一年生黑麦草和多年生黑麦草生长情况以及老叶、功能叶、新叶、茎、根系5个部位As吸收特征及其与茎叶营养元素积累的关系。结果表明,一年生黑麦草As耐性优于多年生黑麦草,株高和根长分别只降低13.3%和3.3%,两种黑麦草5部位干重都呈现降低趋势,但多年生黑麦草老叶和一年生黑麦草根系未达显著水平。两种黑麦草不同部位As分配均表现为根系>老叶>茎>功能叶>幼叶,且多年生黑麦草对As的吸收能力优于一年生黑麦草;茎叶对N、P、K 3种元素的吸收均呈现新叶>功能叶>老叶,对Ca、Mg、Mn 3种元素的吸收则呈现老叶>功能叶>新叶;植物体内As与Mg呈极显著负相关关系,与其他营养元素相关性在两种黑麦草不同部位间表现不同。

Ryegrass is tolerant to heavy metals and has a strong capacity to accumulate them from the soil.Therefore,it is a promising plant for phytoremediation of soils polluted with heavy metals.One of the toxic effects of heavy metals is to disturb the nutrient balance of plants.The aims of this study were to explore the arsenic-and nutrient-absorption characteristics of ryegrass under arsenic stress and to analyze the relationships between As absorption and nutrient accumulation in the stems and leaves.An annual ryegrass(Lolium multiflorum)and a perennial ryegrass(Lolium perenne)were grown in soil without or with As(100 mg·kg-1)in a pot experiment.After 2 months of growth,the plants were harvested and separated into five parts:old leaves,functional leaves,young leaves,stems,and roots.Then,the As and nutrient contents were determined in each part.The results indicated that annual ryegrass was more As-resistant than perennial ryegrass;the shoot length and root length of annual ryegrass were reduced by 13.3%and 3.3%,respectively,by As.The dry weights of all five parts of both ryegrass species were lower in the As treatment than in the control,but the decrease was not significant for the old leaves of perennial ryegrass and the roots of annual ryegrass.In both ryegrass species,the As concentration was highest in the roots,followed by the old leaves,stems,functional leaves,and then young leaves.The As-absorption capacity of perennial ryegrass was higher than that of annual ryegrass.In both ryegrass species,the nitrogen,phosphorus,and potassium absorption was highest in young leaves,followed by functional leaves,and then old leaves.The calcium,magnesium,and manganese absorption capacity was highest in old leaves,followed by functional leaves,and then young leaves.There was a highly significant negative correlation between As and Mg content in leaves.The correlation between As and other nutrients varied among plant parts in the two ryegrass species.