Abstract:

Solution culture experiments were carried out to study uptake character at cotyledon stage and the effect of NO₃^－/NH₄⁺ ratio on nitrate and ammonium uptake at seedling stage with two cultivars of sugar beet, including high sugary Tianyan 7 and prolific Tianyan 8. Vmax of NH₄⁺ was higher in Tianyan 7 than in Tianyan 8 at cotyledon stage (Table 1). It was benefit for Tianyan 7 to uptake NH₄⁺. After cultivated with different NO₃－/NH₄⁺, there was significant deviation of NO₃^－ uptake between Tianyan 7 and Tianyan 8 (Fig.3 and Fig.4). Nitrate uptake was enhanced by optimal ammonium in nutrient solution. Tianyan 7 was more affected than Tianyan 8 (Table 2). Ammonium uptake was also affected by NO₃^－/NH₄⁺ ratio in culture solution (Fig.5 and Fig.6). It was enhanced by high NH₄⁺ concentration in nutrient solution (Table 3), and Tianyan 7 was more sensitive to ammonium uptake than Tianyan 8 due to the different genetic properties of two cultivars. In conclusion nitrogen metabolism can be regulated through regulating the relationship between nitrate and ammonium uptake and assimilation to increase output and quality of sugar beet.

Key words: Sugar beet, Nitrate, Ammonium, Uptake character