Fig. 6. Nitrogen uptake (mg N per plant) as related to the uptake temperature sum (UTS) during uptake for Swingle (SWL) and Volkamer (VLK) seedlings with the 7 mg N L^-1 (A) and 70 mg N L^-1 (B) treatments. Regression equations express N uptake as a function of UTS values expressed in °Cd_N (UTS values assume a base temperature for citrus of 10°C, with one °Cd_N unit being accrued by 2.4 h uptake at 20°C or 1.6 h uptake at 25°C).