甜菜子叶期幼苗硝态氮吸收特性及其与硝酸还原酶活性的关系

６个有代表性的甜菜品种在人工气候室的营养液培养试验表明，甜菜子叶期幼苗对ＮＯ３＾－的吸收要经最初２ｈ的适应阶段后才可均匀进行。均匀吸收后，观察到多倍体的吸收量〉２倍体，倍性相同品种中Ｅ型〉ＮＥ型〉ＮＺ型〉Ｚ型的初步结果。不同类型品种间ＮＯ３＾－吸收的表观米氏常数（Ｋｍ，ａｐｐ）、最大吸收速率（Ｉｍ）有明显差异，除多倍体ＮＺ型品种甜研３０１的Ｋｍ，ａｐｐ较低而Ｉｍ较高外，其余品种的Ｋｍ，ａｐｐ和Ｉｍ

Nitrate Uptake and Its Relation to Nitrate Reductase Activity in Sugar Beet(Beta vulgaris L. ) Seedlings at Cotyledon Stage

Nutrient solution culture showed that sugar beet seedlings at cotyledon stage began to consistently absorb nitrate after the 1 st 2h of adaptation. The amount of nitrate absorption was higher in polyploid than in diploid. The absorption of different cultivars with the same ploidy were in the following order. E type (high yielding), NE type (standard with high yielding) , NZ type(standard with high sugar) , Z type(high sugar). There were different nitrate absorption kinetic parameters, Km, app and Im, in different type of sugar beet cultivars.The order of exudate volume, nitrate amount in exudate and rate of nitrate transport to shoot among cultivars were the same as their Im values. NRA in vivo in cotyledons after 4h induction was significantly and positively correlated with the amount of nitrate absorption during 4h and rate of nitrate transport to shoot, respectively, no matter the reaction solution contained nitrate or not.