Table I.

Component fluxes for NH₄⁺ and NO₃⁻ as determined by compartmental analysis

N Source	N Fluxes
	φoc	φco	φnet	φvac./ass.	φxylem
	μmol g−1 h−1
NO3−	5.98  ± 0.44	0.52  ± 0.04	5.46  ± 0.49	3.18  ± 0.27	2.28  ± 0.32
NO3− (+NH4+)	2.81  ± 0.23	0.32  ± 0.09	2.49  ± 0.24	1.12  ± 0.08	1.37  ± 0.19
NH4+	4.08  ± 0.31	0.99  ± 0.12	3.09  ± 0.33	2.04  ± 0.09	1.05  ± 0.24
NH4+ (+NO3−)	5.07  ± 0.38	0.51  ± 0.07	4.56  ± 0.41	1.74  ± 0.11	2.82  ± 0.17
∑ (NH4+ + NO3−)	7.88	0.83	7.05	2.86	4.19

Rice plants were grown on 100 μm NO₃⁻, 100 μm NH₄⁺, or 100 μm NH₄NO₃. The bottom row indicates combined N fluxes in the NH₄NO₃ treatment. For flux symbols, see Methods. Data are means ± se (n ≥ 10).