Solution culture experiments were conducted to study N uptake kinetics snd the relatively uptake ofammonium- and nitrate-N by rice (Oryza sativa ) at different growth stages. The relative uptake or the ratios(NH:N/NO-...Solution culture experiments were conducted to study N uptake kinetics snd the relatively uptake ofammonium- and nitrate-N by rice (Oryza sativa ) at different growth stages. The relative uptake or the ratios(NH:N/NO-N) of ammonium-N to nitrate-N absorbed by rice varied with its growth stages. At different stages, riceplant had different preference to either ammonium-N or nitrate-N when both NH and NO were present equally inthe nutrient solution. From transplanting to initial tillering, the absorbed ratio was 1. 15 on average, and the absorbed ammonium-N accounted for 53. 48% of the total uptake nitrogen during the same period. During the tilleringperiod, the absorbed ratio was 2. 55 on average, and the absorbed ammonium-N accounted for 71. 8% of the total atthis stage. This phenomenum that rice preferred ammonium-N to nitrate-N during the vegetative growth periodcould be explained by kinetic parameters(Vma. and K.) of absorption. During the reproductive period from elongation to maturity, the absorbed ratios tended more or less towards l, and either of the nitrogen forms could be takenup efficiently by the crop. For the whole growth duration, the absorbed ratios ranged from 0. 98 to 2. 62 with 1. 28on average, the accumulated ammonium-N absorbed being 56. 1 % of the total nitrogen.展开更多
文摘Solution culture experiments were conducted to study N uptake kinetics snd the relatively uptake ofammonium- and nitrate-N by rice (Oryza sativa ) at different growth stages. The relative uptake or the ratios(NH:N/NO-N) of ammonium-N to nitrate-N absorbed by rice varied with its growth stages. At different stages, riceplant had different preference to either ammonium-N or nitrate-N when both NH and NO were present equally inthe nutrient solution. From transplanting to initial tillering, the absorbed ratio was 1. 15 on average, and the absorbed ammonium-N accounted for 53. 48% of the total uptake nitrogen during the same period. During the tilleringperiod, the absorbed ratio was 2. 55 on average, and the absorbed ammonium-N accounted for 71. 8% of the total atthis stage. This phenomenum that rice preferred ammonium-N to nitrate-N during the vegetative growth periodcould be explained by kinetic parameters(Vma. and K.) of absorption. During the reproductive period from elongation to maturity, the absorbed ratios tended more or less towards l, and either of the nitrogen forms could be takenup efficiently by the crop. For the whole growth duration, the absorbed ratios ranged from 0. 98 to 2. 62 with 1. 28on average, the accumulated ammonium-N absorbed being 56. 1 % of the total nitrogen.
