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 (SIR) 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.