Effects of enhanced atmospheric ammonia on physiological characteristics of maize( Zea mays L.)

BACKGROUND Elevated atmospheric NH 3 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 NH 3 on photosynthetic and chlorophyll fluorescence parameters of maize plants.RESULTS At two N levels, NH 3 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 NH 3 . Exposure to 1000  nL  L −1 NH 3 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.CONCLUSION 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 NH 3 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. © 2013 Society of Chemical Industry