Fig. 2. (a) The accumulation of total N (g hill^–1) by (•) rice plants or () the panicles in an irrigated crop during the wet season, represented by sigmoid curves. The equations were N_c = 0.96/[1+(t/37.83)^–2.66] for the rice plants and N_c = 0.37/[1+(t/75.89)^–13.91] for the panicles. The points represent measurements of total net N content of the plants with standard errors (n = 4). (b) Rate of total N uptake by the (solid line) whole plants or the (dashed line) panicles. These curves are the first differential of Eq. [5], with parameters given in the legend to Fig. 2a.