【摘要】 目前湿地水体富营养化越来越严重,其自净能力逐渐下降.通过研究湿地典型浮水植物大薸根系分泌物在磷胁迫下的适应机制,以期为高原湿地污染修复的根际调控措施提供科学依据.实验采用营养液水培方式,研究不同磷浓度胁迫对大薸根系分泌物的影响.结果表明,大薸根系分泌物主要有烷烃、酯、醇、胺、苯和酸类化合物,无磷处理分泌物中烷烃类、酸类和胺类的相对含量较大,分别占总检出面积的41.02%、24.74%和12.11%,其中三类化合物中分泌量最多的物质分别为环戊硅氧烷8.47%,邻苯二甲酸20%,萘胺6.39%;在磷胁迫下,大薸根系分泌物的种类和对应的相对含量差异较大且分泌物的种类逐渐减少,其中邻苯二甲酸的含量在每一种胁迫条件下相对含量均较高;磷胁迫下的大薸根系分泌物有机酸总的相对含量均高于无磷胁迫状态,且随着磷浓度的增加,有机酸的种类和相对含量减少;邻苯二甲酸、苯二羧酸和环己硅氧烷在6种磷胁迫下的根系分泌物中相对含量显著差异且随着磷浓度的增加均出现先增加后减少的变化趋势;磷胁迫浓度与邻苯二甲酸间有极显著的负相关关系,与苯二羧酸存在显著的负相关关系,其中邻苯二甲酸与苯二羧酸间存在极显著的正相关关系.本研究表明磷胁迫下大薸根系增加邻苯二甲酸的分泌是响应环境胁迫的一种重要机制.更多还原

【Abstract】 Wetland eutrophication continues to worsen and reduce the self-purification capability of wetlands. Studies on the root-exudates adaptation mechanism of the floating plant Pistia stratiotes under phosphorus stress may provide a scientific basis for the development of rhizosphere control measures necessary to remediate plateau wetlands. Hydroponic experiments were performed in nutrient solution,and the root exudates of P.stratiotes under different levels of phosphorus stress were characterized. Results showed that the root exudates of P. stratiotes mainly comprised alkanes,esters,alcohols,amines,benzene and acidic compounds. The relative content of alkane,acid and amine in the non-phosphorus treatment secretions were high and accounted for 41. 02%,24. 74%and 12.11% of the total detection area,respectively. Among them,the most secreted substances in the three types of compounds are cyclopentasiloxane 8. 47%,phthalic acid 20%,naphthylamine6.39%. Under phosphorus stress,the chemical species and corresponding relative contents of P.stratiotes root exudates varied greatly. The contents of specific compounds in P. stratiotes root exudates gradually decreased. Nevertheless,phthalate content remained high under each stress condition. The relative contents of organic acids in P. stratiotes root exudates were all higher in the presence of phosphorus stress than those in the absence of phosphorus stress. As phosphorus concentration increased,the types and relative contents of organic acids in P.stratiotes root exudates decreased. The relative contents of phthalic acid,benzene dicarboxylic acid and cyclohexasiloxane in root exudates under six level of phosphorus stresses varied and initially increased and then decreased.Phosphorus stress level was negatively correlated with phthalic acid and benzene dicarboxylic acid contents,whereas phthalic acid and benzene dicarboxylic acid were positively correlated. This study indicated that the increased exudation of phthalic acid by P.stratiotes roots under phosphorus stress is an important mechanism that underlies the response of this plant to environmental stress.更多还原