PAEs高/低吸收累积基因型菜心根际土壤呼吸作用强度的动态变化

Dynamic change of respiration in rhizospheric soils grown high/low PAEs accumulation genotypes of Brassica parachinensis

设置PAEs3个污染水平盆栽PAEs高/低吸收累积基因型菜心(油青60天菜心和特青60天菜心),研究不同生长期根际土壤呼吸作用强度的动态变化及其差异性,初步探讨其与菜心吸收累积PAEs的关系。结果表明,在幼苗期和叶片生长期低浓度(20mg/kg)PAEs对根际土壤呼吸作用有促进作用,而高浓度(50mg/kg和100mg/kg)则有抑制作用;在开花期高浓度(100mg/kg)PAEs对根际土壤呼吸作用也表现出刺激作用。特青60天菜心根际土壤呼吸作用强度显著大于油青60天菜心,前者根际土壤呼吸作用强度的动态变化特征为菜苔形成期≈叶片生长期>开花期≈幼苗期,而后者为菜苔形成期>叶片生长期>开花期>幼苗期。根际土壤呼吸作用强度高低反映了根际土壤微生物活性及其对土壤中PAEs的降解能力大小。因此,特青60天菜心高的根际土壤呼吸作用强度可能是导致其茎叶和根系中PAEs含量显著低于油青60天菜心的重要原因。

Two genotypic cultivars of Brassica parachinensis,Youqing-60（PAEs high-accumulation）and Teqing-60（PAEs low-accumulation）,were cultivated in the soil spiked with three levels（20,50 and 100 mg/kg）of dibutyl phthalate and di（2-ethylhexyl）phthalate to investigate the respiration in rhizospheric soil at four growth stages of Brassica parachinensis and its effects on PAEs accumulation in root and shoot.The results showed that the respiration in rhizospheric soil increased for 20 mg/kg PAEs but decreased for 100 mg/kg PAEs compared with control,which indicated that microbe growth was promoted under lower PAEs concentration but inhibited under higher PAEs concentration.Respiration in rhizospheric soil grown Teqing-60 which decreased in order of flower bud formation stage ≈ leaf growth stageanthesis stage ≈ seedling stage was significantly higher than that in rhizospheric soil grown Youqing-60 which decreased in order of flower bud formation stage leaf growth stage anthesis stage seedling stage.The strength of respiration in rhizospheric soil reflected activity of microbes and their degradation to PAE compounds in rhizospheric soil.It is therefore concluded that higher respiration in rhizospheric soil grown Teqing-60 might be an important mechanism which resulted in significantly low PAE accumulation in Teqing-60 than that in Youqing-60.