EDU对臭氧胁迫下菠菜急性伤害症状和光合特性的影响

如何减轻近地层臭氧(O3)体积分数持续升高对作物的影响是污染生态学研究的热点之一。运用改进的开顶式气室(open-top chambers,OTCs)装置,对嘉兴尖叶、嘉兴圆叶和荷兰35三种菠菜(Spinacia oleracea L.)进行连续5 d,每天8 h的臭氧急性暴露处理,且在暴露前24 h喷施300 mg.L-1质量浓度抗氧化剂ethylenediurea(EDU),研究EDU对臭氧胁迫下菠菜急性伤害症状及光合特性的影响。结果表明:(1)菠菜暴露于高体积分数O3时,叶片出现失水干枯、坏死斑等急性伤害症状,光合色素含量、气体交换参数和光响应参数显著降低,且下降幅度和暴露体积分数呈正相关。(2)菠菜经EDU处理后,光合特性参数明显提高。对O3和EDU作双因子分析发现,随着臭氧体积分数升高,EDU对叶片气体交换参数的影响显著,而对其他参数的影响不明显。由此可见,尽管EDU的防护作用对高体积分数的O3胁迫是有限的,但喷施EDU仍能有效减轻O3对植物的伤害,这对缓解农田生态系统O3污染灾害有积极意义。

Influence of ozone and ethylenediurea (EDU) on physiological characters and foliar symptom of spinach (Spinacia oleracea L.) in open-top chambers

Tropospheric ozone level is projected to continue to increase.How to prevent ozone injury have been drawing great attention in the scientific community.To examine how EDU affects foliar symptom and photosynthetical character of spinach(Spinacia oleracea L.) to high ozone levels,three varieties of spinach(Jiaxing Jianye,Jiaxing Yuanye,Holland 35) were treated with 300 mg.L-1 EDU,and then exposed in open-top chambers for 8h per day,totally 5 days,in Jiaxing,Zhejiang province.The following results were obtained in this research.(1)Foliar injury due to ozone was observed early,such as shrinkage and brown dots.High ozone concentration decreased the values of gas exchange parameter,chloroplast pigment concentration and economic yield.The degressive degree had positively correlated with exposure concentration.(2) EDU significantly increased photosynthetic character.There was a significant interactive effect of ozone and EDU on gas exchange,but some other parameters such as chloroplast pigment concentration were not observed in this experiment.In conclusion,EDU could reduce the ozone damage to spinach,although the effect was limited under high ozone concentration.This study improves our understanding in protection of EDU on plant growth under high ozone concentration.