冬小麦农大139于起身期和拔节期各分三种水平施以铵态氮。在处理前和处理后的生长季节内测定了小麦叶片切段在利用内源基质或外源基质时的硝酸还原酶活性的变化。 实验结果表明,硝酸还原酶活性和籽粒产量与氮素营养水平有关。当利用外源基质时,硝酸还原酶活性达利用内源基质时的3—4倍,而且其高峰较早地出现。当施氮量过多时,酶活性不再增加,同时籽粒产量还有些下降。 Winter wheat Nongda 139 at the beginning and jointing stages of the three levels of ammonium nitrogen applied. Changes in nitrate reductase activity of wheat leaf segments during the use of endogenous or exogenous matrices were measured before and after the growing season. The experimental results show that nitrate reductase activity and grain yield are related to the level of nitrogen nutrition. Nitrate reductase activity was 3-4 times higher than that of the endogenous substrate when exogenous substrate was used, and its peak appeared earlier. When the amount of nitrogen applied is too high, the enzyme activity no longer increases, while the grain yield is still somewhat decreased.