盐碱荒地滴灌施氮对甜菜干物质积累、氮代谢的影响

盐碱荒地膜下滴灌种植甜菜，冠／根比平衡点较常规灌提前１５天以上。收获时，随施氮量的增加块根干物质呈递增趋势。叶丛氮代谢有２个高峰：苗期（６月４日，主要）和块根糖分增长末期（８月２４日）；块根氮代谢的变化与叶丛相似。植株对氮吸收量与施氮量呈正相关（Ｒ＝０．９９６８）；高氮处理的甜菜生育后期地上部氮分配率仍较高，不利于块根增长和糖分积累，甜叶片硝酸还原活性总体上随生育进程而提高，至７月２８日左右达最大值，而后减弱，说明甜菜氮的吸收与同化以生育中前期为主，氮肥的分次施入应在块根增长初期完成。

Effected on Sugar Beet Dried Substance Accumulation, Metabolism of Nitrogen in the Salt-Alkali Wild-Lands by Applying Drip-Irrigation of Nitrogen Fertilizers

The study indicated that the balance point of crona/root advanced about half a month,if we seeded sugar beet under the plastic film into the saline alkali and uncultivated soil.At harvest time,the dried substance increased by applying nitrogenous fertilizers.Metabolism of nitrogen of leaves has two heights:one is in seeding stage(4,June,main)and another is in the end of root sugar increased stage (24,August);the metabolism of nitrogen of sugar roots was the same as the leaves,the plant absorbed nitrogen and applied nitrogen were direct interrelation(R=0.996 8).Enough nitrogen can assign higher nitrogen out of the soil.In the end of sugar growth stage,it didn't help the increasing root and accumulating sugar.The sugar leaf's nitrate and reductases was increased with the stage of sugar growth.It is reached the maximum on 28,July,then it turns weak.It shows that sugar beet absorbed and assimilated nitrogen in the middle of the stage.Applying nitrogenous fertilizers should be finished before the sugar root growth stage.