中文摘要：

以当前甜菜（Beta Vulgaris L.）生产主栽品种KWS0143为试材,设立4个氮素水平（N 0、60、120、180kg/hm2）,研究硝态氮肥对甜菜硝酸还原酶（nitrate reductase,NR）和亚硝酸还原酶（nitrite reductase,NiR）活性以及光合速率与叶绿素总含量的影响,探讨氮素水平与NR及NiRA之间的关系。结果表明,在甜菜生育期间,光合速率呈单峰曲线变化,NR、NiR活性及叶绿素总含量基本呈双峰曲线变化,叶绿素变化曲线的高峰期早于NR活性,NR活性早于NiR活性。氮肥用量在N 120 kg/hm2时显著提高了甜菜光合速率、叶绿素总含量、NR活性和NiR活性。相比于N 120 kg/hm2,N 180 kg/hm2时光合速率及叶绿素总含量没有明显变化,NR与NiR活性则有一定的提高。本试验中,甜菜产量随氮水平的增加而提高;含糖率则相反,随氮水平的增加而降低,N 120 kg/hm2水平下产糖量最高。

英文摘要：

In this paPer, a main cuhivar of sugar beet （Beta Vulgaris L. ） , KWS0143, was used as material to study the effects of nitrate nitrogen fertilization on nitrate reductase （NR） and nitrite reduetase （NiR） activities, photosynthetic rate and total content of chlorophyll. There were four nitrogen levels （N 0, 60, 120 and 180 kg/ha）. The relationships between nitrogen level, NR activity （NRA） and NiR activity （NiRA） were discussed. The results show that the dynamic change of photosynthesis rate is a single peak curve, while the changes of NRA, NiRA and total content of chlorophyll are double peak curves. The peaks of the changing curve of total content of chlorophyll are earlier than those of NRA, and the peaks of NRA are earlier than those of NiRA. Thephotosynthesis rate, total content of chlorophyll, NRA and NiRA are significantly increased under the nitrogen application amount of 120 kg/ha. Compared with 120 kg/ha, the photosynthesis rate and total content of cholorophyllre are not obviously changed under the nitrogen application amount of 180 kg/ha, while to some extent, NRA and NiRA are improved. In this experiment, sugar beet yield is increased with the increase of nitrogen level, while the rate of sugar content is decreased. The highest sugar yield is obtained under the nitrogen applicationamount of 120 kg/ha.