The Relationship Between Nitrogen Uptake Of Crop Seedlings And H～+ Concentration Of Nutrient Solution

Solution culture method in controlled condition were carried out to investigated the relationship between nitrate uptake by crop seedlings and H⁺ concentration changes of culture medium. The obtained results showed that:1. Genotype had more influence on nitrogen uptake, root growth and mass accumulation of rice seedlings than other factors in this research such as different N forms and different pH values of nutrient solution. Seedlings in Indica subspecies growed better than seedlings in Japonica subspecies. The species which growed better had a tendency to use nitrate although nitrate, ammonium has different effects on different species of rice. When supplied with nitrate, the roots of maize growed better and also had a bigger mass accumulation than seedlings supplied with ammonium. Compared with the results in pH 4.0 condition, nitrate uptake rate in pH 6.0 condition was higher and ammonium uptake by maize seedlings showed a tendency that it was rapid in pH6.0 condition than in pH4.0 condition. Like corn, wheat was more adaptable to nitrate.2. The H⁺ absorbed into crop increaseed with the growth of plant and its increasing ability of nitrate uptake. NH₄⁺ uptake by plants showed the similar tendency: The H⁺ effluxed into nutrient solution increaseed when the plant has been cultured more days. The ratio of H⁺ and NO₃^- concentration changes in nutrient solution (â–³H⁺:â–³NO₃^-) in pH6.0 condition was far lower than in pH4.0 condition. The pH values of cultural medium changed easier when supplied with ammonium.3. In both solution pH conditions, the Vmax of nitrate uptake increased but Km decreased by the addition of glutamine into nutrient solution.