Pb胁迫下氮素形态对日本毛连菜生物量、叶绿素含量及抗氧化酶活性的影响

摘要

In order to reveal the effects of different nitrogen forms and nitrogen application amount on Picris ja-ponica Thunb.growth,physiological and biochemical characteristics under the different concentrations of Pb stress , pot experiment was performed to study the effects on the Picris japonica Thunb.biomass,chlorophyll content and antioxidant enzyme activity .The results showed that ,with increasing nitrogenous fertilizer ,the biomass increased first and then reduced.Under the low concentrations of Pb stress (500 mg/kg),with NH4+-N fertilizer,the chlorophyll content and the CAT activities in Picris japonica Thunb.increased first,and then reduced SOD activity increased gradually , POD activity decreased first and then increased .In the case of NO 3--N fertilizer ,the chlorophyll and SOD activity increased first ,then decreased ,the activity of POD and CAT decreased gradually .Under the high concentra-tions of Pb stress (2 000 mg/kg),with NH4+-N fertilizer application,the chlorophyll content and the POD activity first increased and then decreased , meanwhile CAT and SOD activity decreased first and then increased , with in-creasing nitrogenous fertilizer .With NO3--N fertilizer ,only CAT activity increased first and then decreased ,and oth-er indicators had no obvious changes .As a result,the appropriate NH4+-N fertilizer was more useful to Picris japoni-ca Thunb′s growth .It not only helped to enhance the chlorophyll content ,but also increased the activity of antioxi-dase .It was crucial to make efforts in increasing plant biomass and medicinal value ,and it had practical significance on remediation of lead contaminated soil .%为揭示Pb胁迫下氮素形态及施氮量对日本毛连菜生长及生理生化特性的影响，采用盆栽试验方法，针对不同浓度Pb胁迫下铵态氮和硝态氮及其施氮量对日本毛连菜生物量、叶绿素含量和抗氧化酶活性的影响进行研究。结果表明，在Pb胁迫下，日本毛连菜的生物量随施氮量的增加总体呈先上升后下降的趋势。在低浓度Pb胁迫下，施用铵态氮肥时，日本毛连菜叶绿素含量和CAT活性随施氮量的增加呈先升后降的趋势，SOD活性逐渐增加，POD活性呈先降后升的趋势，施用硝态氮肥时，植株叶绿素含量和SOD活性的变化趋势为先升后降，POD和CAT的活性呈逐渐下降的趋势；在高浓度Pb胁迫下，施用铵态氮肥时，日本毛连菜叶绿素含量、POD活性随施氮量的增加呈先升高后降低的趋势，而SOD、CAT活性则呈先降低后升高的趋势，施用硝态氮肥时，CAT活性随施氮量的增加呈先上升后下降的趋势，其他指标则无明显的变化趋势。无论在何种Pb浓度胁迫下，适量的铵态氮肥更有利于日本毛连菜的生长，不仅能提高叶片叶绿素含量，还能增加其抗氧化酶活性，这对于增加日本毛连菜的生物量，提高其修复铅污染土壤的能力具有实际意义。