氮素形态对甜菜氮糖代谢关键酶活性及相关产物的影响

Effects of Nitrogen Forms on Key Enzyme Activities and Related Products in Sugar and Nitrogen Metabolism of Sugar Beet( Beta vulgaris L.)

用营养液培养的方法 ,以甜研 7号为试验材料 ,研究了同一氮素水平不同氮素形态比例对甜菜氮、糖代谢关键酶 :硝酸还原酶 (NR)、谷氨酰胺合成酶 (GS)和蔗糖合成酶 (SS)活性及相关产物的影响。结果表明叶片中 NR活性随NO-3比例增加而增加 ;根和叶片中 GS活性 ,当 NH+4小于 NO-3时 ,随 NH+4比例增大而增加 ,当 NO-3∶ NH+4为 1∶ 1时活性最大 ,当 NH+ 4大于 NO- 3时活性下降 ;根中 α-氨基态氮和蛋白质含量的变化与 GS活性的变化基本一致 ;生育后期 NH+ 4和 NO- 3混合培养的甜菜根中 SS合成方向的活性明显高于单一氮营养的 ,蔗糖的变化与之相对应 ;而葡萄糖和果糖则随 NH+4浓度增加而降低。块根中含糖率随 NH+4浓度增加而增加 ,块根产量和产糖量以 NO-3∶ NH+4为1∶

Effects of the proportion of different nitrogen forms on the activity of key enzymes and related products in sugar and nitrogen metabolism of sugar beet were investigated. Cultivar Tian Yan 7(a variety of sugar beet) was planted in nutritional liquid with different proportions of NO - 3/NH + 4. The result showed that nitrate reductase (NR) activity in leaves gradually was enhanced as the increase of NO - 3 in the nutritional liquid. Glutamina synthetase (GS) activity in roots and leaves was enhanced with NH + 4 increasing when the rate of NO - 3/NH + 4>1 and reached the highest when the rate of NH + 4/NO - 3=1, and declined when the NO - 3/ NH + 4<1. The changes of α aminonitrogen and protein were similar to that of GS activity. In the anaphase of growth, sucrose synthase(SS) synthetic activity in root was obviously higher in the treatment with NH + 4 and NO - 3 than that with NH + 4 or NO - 3 alone; the change of sucrose content in root was in accordance with SS activity. Glucose and fructose contents were declined as NH + 4 increasing. The sugar content in root was enhanced as NH + 4 increasing. Both of the root and sugar yields were the highest when the proportion of NH + 4 and NO - 3 was 1∶1.