Department of Plant Sciences

Most of plants uptook NO3--N faster at the low pH 4.0 than at pH 6.0 and uptook NH4+-N slower, but few experimental plants showed different tendency. The exceptions probably due to excessive nitrate outflux of some maize and wheat varieties (Suyu 19. Zhendan958 and Yangmai12) at low pH. Some other experimental plants (Huaidao 8. Nongda108 and Yangmai12) even show no obvious NH4+ toxic symptoms at pH 4.0. The effect of low pH on uptake rate of NH4+-N and NO3--N varied with plant species, varieties, and the difference increased with the growth age of seedlings.