title: [Effects of exogenous silicon on physiological characteristics of cucumber seedlings under ammonium stress].
abstract: The present study evaluated the effects of exogenous silicon on growth and physiological characteristics of hydroponically cultured cucumber seedlings under ammonium stress. The results showed that the growth, especially the aerial part growth of cucumber seedlings cultured with ammonium were significantly inhibited than those with nitrate, especially after treatment for 10 d, the aerial part fresh mass of cucumber seedlings were reduced 6.17 g per plant. The accumulation of reactive oxygen species (ROS) was also promoted in cucumber seedlings under ammonium, and the contents of O2*- and H2O2 were significantly increased in cucumber leaves. With the exogenous silicon treatment, the activities of superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), ascorbate peroxidase (APX) were significantly improved, the ability to remove reactive oxygen species was enhanced, the contents of O2*- and H2O2 were significantly reduced in cucumber leaves, decreasing the reactive oxygen damage to the cell membrane, and the ratio of electrolyte leakage and the content of MDA in cucumber leaves. Also, with exogenous silicon treatment, the plasma membrane and activity of vacuolar membrane H(+)-ATP was significantly increased, transport capacity of intracellular proton was improved, and the level of ammonium in cucumber body was significantly reduced, thereby reducing the toxicity of ammonium. In conclusion, exogenous silicon could relieve ammonium stress, by increasing the antioxidant enzyme activity, H(+)-ATP activity, and decreasing the ammonium content in cucumber seedlings.
authors.forename: Qing-Hai
authors.initials: QH
authors.lastname: Gao
authors.forename: Ya-Kun
authors.initials: YK
authors.lastname: Wang
authors.forename: Xiao-Min
authors.initials: XM
authors.lastname: Lu
authors.forename: Shuang-Shuang
authors.initials: SS
authors.lastname: Jia
mesh_terms: D064751:Ammonium Compounds / Q000633:toxicity*; D000975:Antioxidants; D002374:Catalase; D018553:Cucumis sativus / Q000187:drug effects / Q000502:physiology*; D006861:Hydrogen Peroxide; D010544:Peroxidases; D018515:Plant Leaves; D017382:Reactive Oxygen Species; D036226:Seedlings / Q000187:drug effects / Q000502:physiology; D012825:Silicon / Q000494:pharmacology*; D013482:Superoxide Dismutase
chemical_list: D064751:Ammonium Compounds; D000975:Antioxidants; D017382:Reactive Oxygen Species; D006861:Hydrogen Peroxide; D010544:Peroxidases; D002374:Catalase; D013482:Superoxide Dismutase; D012825:Silicon