Effects of N‐source, light intensity and temperature on nitrogen metabolism of bahiagrass

Abstract

Under greenhouse conditions, a study was made on the effects of nitrogen (N) source (NO3 or NH4), mode of application (single vs. split) and nitrification inhibition on the N-uptake and metabolism of bahiagrass. Variations in light and temperature in the greenhouse affected the N-metabolism of bahiagrass plants. Nitrate fed plants had nitrate reductase activity (NRA) pattern different from that of NH4-fed plants. Amino-N accumulation patterns were similar for plants under both N-sources although amino-N levels in leaves of NH4-fed plants were much smaller than that of NO3 plants. Nitrate accumulation in leaves showed inverse trend to that of roots in plants fed both NO3 or NH4. To the sharp peaks in NO3 levels in roots due to increases in light and temperature corresponds a sharp decrease of its levels in leaves. For both NO3 or NH4 treatments, soluble-N accumulated most in the rhizomes of bahiagrass plants, whereas protein N accumulated most in leaves, suggesting that rhizomes had a buffering effect on the NO3 fluxes to leaves. This presumably resulted in a lag in the NRA response of the NO3-fed plants to increases in light and temperature.