2种基因型菜心根系分泌物对水稻土中DEHP解吸效应的初步研究

A Preliminary Study on the Effects of Two Genotypes of Brassica parachinensis Root Exudates on DEHP Desorption in Paddy Soil

在邻苯二甲酸二（2-乙基己基）酯（DEHP）不同污染水平下水培油青60天菜心和特青60天菜心,采用蒸馏水法收集根系分泌物,研究其根系分泌物对水稻土壤中DEHP解吸效应的影响及其与菜心吸收累积DEHP的关系。结果表明,2种基因型菜心根系分泌物均能显著提高土壤中DEHP的解吸效应,添加根系分泌物处理上清液中DEHP含量是对照处理的1.9~26.6倍,较高污染条件下2种基因型菜心根系分泌物对土壤中DEHP具有更强的解吸效应。油青60天菜心根系分泌物的解吸效应大于特青60天菜心,前者是后者的1.6~4.6倍。2种基因型菜心根系分泌物对土壤中DEHP的解吸效应强弱与其根系、茎叶中DEHP含量达极显著相关（r≥0.924 9）,说明2种基因型菜心根系分泌物对DEHP解吸效应的影响可能是导致其根系、茎叶中DEHP含量差异的重要原因之一。

The root exudates of two genotypes of Brassica parachinensis,DEHP high-accumulating Youqing-60 and low-accumulating Teqing-60 which were cultivated in hydroponic systems contaminated with DEHP（20 mg.L-1 and 50 mg.L-1）were collected by sterilized distilled water at 15th and 30th day to investigate their effects on the desorption of DEHP in paddy soil and on the accumulation of DEHP in root and shoot of two genotypes of Brassica parachinensis.The results showed that DEHP concentrations in supernatant of treatments added root exudates were higher than that added distilled water（1.9~26.6 times）,indicating that root exudates of two genotypes of Brassica parachinensis improved significantly DEHP desorption in paddy soil.With the increase of DEHP concentrations in hydroponic systems,the effects of both two genotypes of Brassica parachinensis root exudates on DEHP desorption in paddy soil increased,and significant differences were observated between some treatments.DEHP concentrations in supernatant of treatments added Youqing-60 root exudates were higher by 0.6~3.6 times than those added Teqing-60 root exudates.Moreover,DEHP concentrations in supernatant of treatments added root exu-dates at 15th day were higher than those at 30th day（except the treatment of DEHP 20 mg.L-1 of Teqing-60）,implying that the effects of root exudates on DEHP desorption at early grow stage were higher than at late grow stage.Significant correlation（r≥0.924 9）was ob-served between DEHP concentrations in supernatant of treatments added two genotypes of Brassica parachinensis root exudates and DEHP contents in root and shoot.It was therefore concluded that higher desorption of DEHP in soil might be an important mechanism which resulted in significantly higher DEHP accumulation in Youqing-60 than in Teqing-60.