Fig. 6.

¹⁵N influx rates of the roots of cvs Nanguang and Eilo as measured by ¹⁵NH₄ ⁺ and ¹⁵NO₃ ^–. Seedlings were grown under 1.43mM NH₄ ⁺ for 14 d and then N starved for 3 d, before being resupplied with ¹⁵NH₄ ⁺, ¹⁵NH₄ ⁺/¹⁵NO₃ ^– (75/25, PNN), ¹⁵NH₄ ⁺+SNP (2.5 μM, cv. Nanguang; 5 μM, cv. Eilo), and ¹⁵NH₄ ⁺/¹⁵NO₃ ^– (75/25, PNN)+cPTIO (80 μM for the two cultivars) for 10min before harvest. Data are means ± standard error (SE), and bars with different letters indicate significant differences at P<0.05, as determined by ANOVA.