棕壤小白菜施镍生物效应及临界值

Biological Effect and Critical Value of Nickel Application on Pakchoi in Brown Soil

利用盆栽试验，研究了棕壤土施镍（Ni）对小白菜生长发育及矿质营养吸收与积累的影响，并通过小白菜生物量、地上部茎叶Nj含量及土壤有效态Ni含量的变化确定了土壤Ni污染的毒性临界值。结果表明，土壤施Nj量在0—25mg／kg范围，小白菜生物量随施Nj量的增加而增加，施Ni量〉25mg／kg，随施Ni量增加，生物量呈极显著下降。小白菜茎叶和根系中矿质营养吸收与Ni含量表现为一定的协同或拮抗关系。以生物减产量突变点为依据，确定棕壤土施Ni毒害临界值为：土壤全量Ni为66．36mg／kg，有效态Ni含量为6．21mg／kg（DTPA）和茎叶Ni含量为16．40mg／kg。

A pot experiment was carried out to study effect of application of Ni on growth and uptake and accumulation of mineral nutrients ofpakchoi in brown soil, and critical value for soil Ni pollution to be toxic to pakchoi through monitoring change in biomass production of pakchoi. The critical value is characterized by Ni content in the shoot and content of available Ni in the soil, Results showed that biomass increased significantly with the increase in Ni application rate within the range of 0- 25 mg/kg, while it decreased obviously when the Ni application rate beyonded 25 mg/kg. The uptake of mineral nutrients of the plant showed a certain relationship of synergism or antagonism to Ni content. With the point where biomass droped by 10% set as the critical point for soil Ni pollution to be toxic to pakchoi in brown soil, the critical value is 66.36 mg/kg for total Ni, 6.21mg/kg for available Ni （DTPA）, and 16.40 mg/kg for Ni content in stem and leaves.