中文摘要：

为了给专用小麦氮素利用效率的提高提供依据，采用砂基水培方法，研究了强筋小麦豫麦34、郑麦9023、郑农16，中筋小麦豫麦49和弱筋小麦豫麦50一叶一心期叶片的氨同化关键酶（谷氨酰胺合成酶，GS；谷氨酸合成酶，GOGAT）活性和不同氮素形态（NH2-N、NH4^＋-N和NO3^--N）对四叶一心期氨同化关键酶活性的影响。结果表明，一叶一心期，不同类型专用小麦GS总活性表现为：弱筋型〉中筋型〉强筋型。胞质型GS（GS1）活性高于质体型GS（GS2）。不同品种间GS1活性差异小，GS2活性差异极显著，且强筋型〉中筋型〉弱筋型。GOGAT活性表现为弱筋型和中筋型略高于强筋型。四叶一心期，强筋型品种和弱筋型品种GS活性以硝态氮处理最高，中筋型品种以尿素处理最高。同时，GS1活性均呈下降趋势，不受品种和氮素形态的影响；GS2受品种和氮素形态影响较大。NH4^＋-N下，中筋型和弱筋型小麦GS2活性均提高，强筋小麦均下降；NH2-N下，中筋小麦豫麦49的GS2活性持续提升，豫麦34的GS2活性保持平衡，其他品种均降低；NO3^--N下，强筋型和中筋型品种的GS2活性均下降，弱筋小麦增加。说明弱筋小麦GS2活性对氮的敏感性最强，其次是中筋型小麦，强筋小麦GS2受氮素的激活效应最弱。

英文摘要：

With nutrient solution culture method,the activities of key enzymes for ammonia assimilation（glutamine synthetase and Glu synthetase） in wheat leaves at one and a half leaves stage were carried out with strong-gluten wheat cultivars of Yumai 34,Zhengmai 9023 and Zhengnong 16,and medium-gluten wheat cultivar of Yumai 49,and weak-gluten wheat cultivar of Yumai 50;the effects of nitrogen forms,NO3^-,NH4^＋ and urea on the enzyme activities were studied in the fourth leaf full expended stage.The result showed that at one and a half leaves stage,the total GS activities showed as： weak-gluten wheat cultivar〉medium-gluten wheat cultivar〉 strong-gluten wheat cultivars.The activities of GS1 were higher than that of GS2,and the differences of the activities of GS1 among different cultivars were very little whereas that of GS2 were very large as strong-gluten wheat cultivars〉medium-gluten wheat cultivar〉weak-gluten wheat cultivar.The activities of GOGAT of weak and middle gluten wheat cultivars were slightly higher than that of strong-gluten wheat cultivars.At the fourth leaf full expended stage,as to strong and weak gluten wheat cultivars,the GS activities of NO3^-treatments were the highest;as to medium-gluten wheat cultivar,the GS activities of urea treatment were the highest.At the same time,the GS1 activities decrease in all treatment.Cultivars and N forms had no effect on GS1 but more effect on GS2.NH4^＋ could increased the GS2 activity of medium and weak gluten wheat cultivars while decreased that of strong-gluten wheat cultivars;urea could increased the GS2 activity of medium-gluten wheat cultivars,maintained that of Yumai34 in constant level,while decreased that of weak-gluten wheat cultivar and other strong-gluten wheat cultivars;NO3^-increased the GS2 activity of weak-gluten wheat cultivar while decreased that of strong and medium-gluten wheat cultivars.The results showed that weak-gluten wheat cultivar was more sensitive to N form while strong-gluten wheat cultivars were more insensitive to N fo