title: Effects of enhanced atmospheric ammonia on physiological characteristics of maize(Zea mays L.).
abstract: BACKGROUND
  Elevated atmospheric NH₃ may affect photosynthesis rates and biomass production of crops and the effect may be responsible for the soil nitrogen (N) levels. Plants were exposed to 0 and 1000 nL L⁻¹ with and without N (+N and - N) in open-top chambers (OTCs) to investigate effects of atmospheric NH₃ on photosynthetic and chlorophyll fluorescence parameters of maize plants.
  
  
  RESULTS
  At two N levels, NH₃ exposure at 1000 nL L⁻¹ led to an increase in plant height, biomass production, net photosynthetic rates (P(n)) and stomatal conductance (g(s)) compared to ambient NH₃. Exposure to 1000 nL L⁻¹ NH₃ resulted in a significantly higher photochemical quenching (q(p)) and non-photochemical quenching (q(np)), while minimal fluorescence (F(o)), maximum fluorescence (F(m)) and maximum photochemical efficiency (F(v)/F(m)) were not affected. For shoots, N concentrations for - N-1000 and + N-1000 treatments were 49-50% and 26-30% higher, respectively, than those of - N-0 and + N-0 treatments.
  
  
  CONCLUSIONS
  No visible damage was observed and plants growing on low soil N took up more leaf-derived N than those fertilised at higher N level. Therefore, atmospheric NH₃ can be considered as a quick fertiliser for crops and should be estimated in a further study with soil N fertilisers in order to reduce the dosage.
authors.affiliation: State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, Northwest A&F University, Yangling, Shaanxi 712100, China.
authors.forename: Xiaoli
authors.initials: X
authors.lastname: Chen
authors.forename: Shiqing
authors.initials: S
authors.lastname: Li
mesh_terms: D000393:Air Pollutants / Q000009:adverse effects / Q000378:metabolism; D000641:Ammonia / Q000009:adverse effects / Q000378:metabolism*; D001273:Atmosphere Exposure Chambers; D002681:China; D002734:Chlorophyll / Q000096:biosynthesis*; D055724:Electrophysiological Phenomena; D007700:Kinetics; D009584:Nitrogen / Q000032:analysis / Q000378:metabolism; D058458:Nitrogen Cycle; D010788:Photosynthesis; D035261:Plant Components, Aerial / Q000737:chemistry / Q000254:growth & development* / Q000378:metabolism; D018515:Plant Leaves / Q000737:chemistry / Q000254:growth & development / Q000378:metabolism; D018521:Plant Physiological Phenomena; D018520:Plant Shoots / Q000737:chemistry / Q000254:growth & development / Q000378:metabolism; D054046:Plant Stomata / Q000737:chemistry / Q000254:growth & development / Q000378:metabolism; D012987:Soil / Q000737:chemistry; D014835:Volatilization; D003313:Zea mays / Q000737:chemistry / Q000254:growth & development / Q000502:physiology*
chemical_list: D000393:Air Pollutants; D012987:Soil; D002734:Chlorophyll; D000641:Ammonia; D009584:Nitrogen
keywords: atmospheric ammonia; chlorophyll fluorescence; maize; nitrogen levels; open-top chambers (OTCs)