施氮对不同品种冬小麦植株硝态氮和硝酸还原酶活性的影响

Effect of Nitrogen Fertilization on Nitrate Nitrogen Contents and Nitrate Reductase Activities in the Plants of Different Winter Wheat Varieties

以黄土高原南部半湿润区土垫旱耕人为土为供试土壤进行盆栽试验,以NR 9405、9430、偃师9号、小偃6号、陕229号和西农2208冬小麦品种为供试材料,研究施氮对不同品种冬小麦植株硝态氮含量和硝酸还原酶活性(NRA)的影响.结果表明,施氮能明显增加叶片NRA.不施氮时除小偃6号和偃师9号外,其余品种NRA在全生育时期的动态变化均呈双峰曲线,2个高峰期分别在返青期和开花期,且开花期高峰值(36.17 NO2-μg.-g 1FW.h-1)明显比返青期峰值(15.407 NO2-μg.-g 1FW.h-1)大;施氮时不同品种叶片NRA在全生育期呈单峰曲线变化,最高峰在开花期,平均峰值为80.93 NO2-μg.-g 1FW.h-1),比同期不施氮处理增加1倍以上.施氮后地上部硝态氮含量在各时期均显著提高,在小麦生育前期(出苗到拔节)表现最为显著.氮肥对不同品种硝态氮含量的影响程度基本上与对NRA的影响程度相反,即施氮后硝态氮增加幅度小的品种,NRA却增加幅度大.

NR9405 ,Yanshi 9 ,Xiaoyan 6 and Shaan 229 ,winter wheat varieties ,were pot planted in Eum-Orthic Anthrosols of the semi-humid region standing in the southern part of the loess plateau,in order to study the effects of nitrogen fertilization on nitrate nitrogen contents and nitrate reductase activities in the plants of different winter wheat varieties. The results showed that nitrogen fertilization could remarkably increase nitrate reductase activity in the leaves. Without nitrogen fertilization,nitrate reductase activity varied in a double-peak curve during the whole growth periods of all the wheat varieties but Xiaoyan 6 and Yanshi 9,and the two peaks appeared at the regreening and flowering stages , respectively ; the peak at the flowering stage （36.17 NO2^-μg·g^-1FW·h^-1） was obviously higher than at the regreening stage （15. 407 NO2^-μg·g^-1FW·h^-1）. With nitrogen fertilization,nitrate reductase activity varied in single-peak curve in the leaves of different varieties and the peak appeared at the flowering stage averaging 80.93 NO2^-μg·g^-1FW·h^-1 ,more than one times as much as that at the same stage without nitrogen fertilization. After nitrogen fertilization ,nitrate nitrogen content significantly increased in aboveground parts of wheat at various growth stages and this increase appeared the most remarkable in the early growth （from seedling emergence to jointing）. Nitrogen fertilization affected nitrate nitrogen contents of the different varieties in an opposite manner as it did nitrate reductase activities of the varieties,i, e. after nitrogen fertilization,the varieties that presented small-increment nitrate content would present large-increment nitrate reductase activity.