Characteristics of NH and NO Fluxes in Roots under Different Nitrogen Treatments.

To understand the characteristics of net NH and NO fluxes and their relation with net H fluxes in , net fluxes of NH, NO and H were detected by a scanning ion-selective electrode technique under different forms of fixed nitrogen (N) and experimental conditions. The results showed that higher net NH and NO fluxes occurred at 2.1-3.0 mm from the root apex in and . Compared to NH or NO alone, more stable net NH and NO fluxes were found under NHNO supply conditions, of which net NH flux was promoted at least 1.71 times by NO, whereas net NO flux was reduced more than 81.66% by NH in all plants, which indicated that NH is preferred by plants. and had the largest net NH and total N influxes when NH:NO was 3:1. N Atom% and activities of N assimilation enzymes were improved by single N fertilization in the roots of . In most cases, net H fluxes were tightly correlated with net NH and NO fluxes. Thus, both N forms and proportions could affect N uptake of . These findings could provide useful guidance for N management for better productivity of plants.