【摘要】 采用水培方式研究了LaC l3对140 mmol.L-1NO3-硝酸盐胁迫下黄瓜幼苗光合特性的影响.结果表明:硝酸盐胁迫显著降低了黄瓜幼苗叶绿素及类胡萝卜素含量,叶片Mg2+-ATPase、Ca2+-ATPase活性也随之降低;硝酸盐胁迫7 d,黄瓜幼苗叶片光合速率的降低以气孔限制为主,叶片AQY与CE下降,胁迫12 d则以非气孔限制为主.硝酸盐胁迫下,外加LaC l3可以使黄瓜叶片保持较高的Mg2+-ATPase、Ca2+-ATPase活性及叶绿素和类胡萝卜素含量,尤其是外加低浓度(20μmol.L-1)LaC l3显著增加了叶片类胡萝卜素含量;LaC l3还具有降低气孔关闭、改善叶片气体交换功能,减缓叶片Fv/Fm、ФPSII、AQY、CE及qP的降低幅度等作用,使叶片在盐胁迫下保持较高的光能利用率及CO2同化能力.20μmol.L-1LaC l3可以有效缓解硝酸盐对黄瓜幼苗光合作用的影响,而200μmol.L-1LaC l3在胁迫初期对黄瓜幼苗有缓解效果,后期则效果不明显.该结果可为设施土壤的改良提供新的途径.更多还原

【Abstract】 By the method of hydroponic culture,this paper studied the alleviation effects of LaCl3 on the photosynthetic characteristics of cucumber seedlings under nitrate(140 mmol NO3-·L-1) stress,with the related mechanisms discussed.Under nitrate stress,the seedlings leaf chlorophyll and carotenoids contents decreased significantly,and the leaf Mg2+-ATPase,Ca2+-ATPase activities also decreased.On the 7th day of nitrate stress,the decrease of seedlings photosynthetic rate was mainly due to stomatal limitation;but on the 12th day of nitrate stress,the decrease was mainly due to no-stomatal limitation.Supplement with LaCl3 could make the cucumber seedlings keep relatively higher leaf Mg2+-ATPase and Ca2+-ATPase activities and chlorophyll and carotenoids contents,and applying 20 μmol·L-1 of LaCl3 could increase the carotenoids content significantly.LaCl3 could also improve the leaf gas exchange,and alleviate the decrease of leaf Fv/Fm,ФPSII,AQY,CE,and qp under nitrate stress,which helped the leaves making good use of light energy and maintaining higher CO2 assimilation capacity.An additional 20 μmol·L-1 of LaCl3 could alleviate the nitrate stress on the photosynthesis of cucumber seedlings efficiently,but an additional 200 μmol·L-1 of LaCl3 only had the alleviation effect at the initial period of nitrate stress.Our results could benefit to the improvement of greenhouse soil.更多还原