Nitrogen and carbon uptake by some Rice cultivars from15NH4Cl and 13C-U-glucose labeling fertilizer

Abstract This experiment was conducted to determine the effects of the application of 15NH4Cl (1.0 atom %) and 13C-Uglucose (99.8 atom %) on the nitrogen and carbon uptake by 12 different rice cultivars. Chemical nitrogen fertilizer and glucose was applied at a rate of 100 kg N ha−1 and 40 mg kg −1 soil, respectively. The ratio of 13C and 15N to the total C and N content of samples was calculated. The results showed that, N uptake derived by chemical fertilizer application to the rice cultivars exhibited significant differences. The rice cultivars recovered about 48.1- 66.2% of applied chemical fertilizer and the amount of 15N taken up by rice grain was higher than that of straw and roots. A high recovery percentage of glucose-carbon was observed with cultivars Jucar, Sakha-104, and Koshihikari rice cultivars. The application of 13C-U-glucose permitted a rough estimation of the minimal contribution of intact glucose molecules to glucose derived 13C acquisition by rice cultivars. The results showed that in all cultivars, the 13C uptake from the glucose by the root accounted for not more than 2.06% of total C uptake by the plants, however, the contribution of the rice roots to C uptake was significantly different (P > 0.05) among the 12 studied rice cultivars.