水培硝态氮浓度对冬小麦幼苗氮代谢的影响

Effect of NO-3 N concentration on nitrate nitrogen metabolism of winter wheat seedlings under water culture

关键词:  NO-3 N  冬小麦  水培  氮代谢

Key words:  NO-3 N  winter wheat  water culture  nitrogen metabolism

摘要:

以Hoagland营养液为培养基质，以冬小麦为试材，动态测定高（含NO-3 N 15 mmol•L 1）、中（含NO-3 N 7.5 mmol•L 1）、低（含NO-3 N 2.5 mmol•L 1）三种氮水平处理条件下硝态氮的吸收和累积、硝酸还原酶活性、铵态氮含量、小麦吸氮量及根系活力，分析不同供氮水平对冬小麦硝态氮吸收、还原、转运的影响，探讨不同供氮条件下，植物地上、地下部分硝态氮代谢的变化。结果表明：水培条件下，营养液NO-3的消耗量、pH变化、植株全氮以及根系活力均能较好地反映不同氮水平对植株硝态氮代谢的影响；高氮条件下植物体内NO-3进一步同化较中氮弱，冬小麦植株积累了较多的NO-3，而非过多的吸收营养液中的NO-3。不同氮浓度处理下，NO-3的供应与植株NRA间无相关关系，根系与地上部的变化曲线不同；NO-3供应浓度高时，植物地上部是主要同化部位；低浓度时根部是主要同化部位。虽然NO-3是一种安全的氮源，但供应过高则抑制体内硝态氮进一步同化，而供应过低，植物吸收NO-3量不足、根系活力下降，不利于小麦幼苗氮素营养。

Abstract:

In cultural liquid Hoagland，with winter wheat set as testing object，this research tested dynamically the absorption and accumulation of nitrate nitrogen，the activities of nitrate reductase，the content of ammonium nitrogen，the nitrogen absorption of the wheat and root activity under the three levels of nitrogen content high，medium and low. This research completely analyzed the influence over the absorption，reduction and transferability of nitrate nitrogen of winter wheat being treated with different nitrogen leves，and investigates the change of nitrate nitrogen metabolism on above ground and under ground parts of plant，under different nitrogen levels. The research indicated that，in water culture，the consumption of nutrient solution NO-3，the change of pH values，complete nitrogen of plant and root activity reflected the effect on metabolism of plant nitrate nitrogen well under different nitrogen levels；Under high nitrogen level，assimilation of NO-3in plant was weaker than that of medium nitrogen level as winter wheat accumulates adequate NO-3itself rather than absorbing more from nutritional liquid. Under different nitrogen levels，no relationship between NO-3 supply and plant NRA was found，the curve for the roots and above ground prat varied，under high NO-3 level，the above ground part of the plant was the main assimilated part；on the contrary，under low NO-3 level，the root part of the plant was the main assimilated part. Even NO-3 was a safe nitrogen resource，it could restrain the further assimilation of nitrate nitrogen in plants under too much higher level，on the other side，it could lead to an insufficiency absorption of NO-3 and the decrease of root activity，which was not good to the absorption of nitrogen nutrition of young wheat seedling.