Effects of Elevated Ammonia Concentration and Nitrogen Status on the Growth and Yield of Winter Wheat

Elevated atmospheric NH 3 may affect productivity of crops in part by altering N assimilation, and the effect may be responsible for the N status of the plant. To investigate this possibility, measurements of plant height, leaf area per plant, net photosynthesis rate ( P n ), plant biomass production, shoot/root (S/R) ratio, grain yield and its components were used to examine the effects of elevated NH 3 concentration in combination with N status on growth and yield in pot‐grown winter wheat ( Triticum aestivum L.) using open‐top chambers. After 2 month of NH 3 injection, elevated NH 3 significantly increased plant height, leaf area per plant, shoot biomass production (total biomass), and S/R ratio in the N‐deprived plants in both years, but the corresponding values in the N‐sufficient plants were reduced. The P n values were increased with NH 3 enhancement both in the presence and absence of N in the potting soil in each experimental year, but the increment of P n in N‐deprived plants was two times higher than that of the N‐sufficient plants in both years. At harvest, grain yields of N‐deprived winter wheat exposed to elevated levels of NH 3 were increased by 21% and 23% than that of N‐deprived winter wheat exposed to 0 levels of NH 3 , while grain yields of N‐sufficient winter wheat exposed to elevated levels of NH 3 were decreased by 27% and 23% than that of N‐sufficient winter wheat exposed to 0 levels of NH 3 in 2007 and 2008, respectively.