... Furthermore, total nitrogen in rice was employed as a state variable. Above-ground rice biomass, and underground rice biomass were calculated from the total nitrogen in rice with a certain proportional ... fraction of rice (0.7) [g/g] (based on the measurement in this study), w tot is the total weight of the rice [g/m 2 ], w a is the weight of the above-ground part of the rice [g/m 2 ], and f Nw ,rice ... rice [g/m 2 ], and f Nw ,rice is the rice nitrogen / weight ratio [g-N/g]. The variations of ζ i and f Nw ,rice are discussed below. Nitrogen Uptake by Rice The rice growth rate is affected by radiation,...