Abstract: In order to define the effect of different nitrogen (N) topdressing stage on stem morphology,physical and chemical material and its relationship with lodging resistance in oats,this study used two forage oats varieties (Avena sativa L.) as materials,setting N topdressing stage in the field condition,to measure plant morphology,stem index of physical and chemical properties,lodging resistance and oats yield. The results showed that the plant height,the length of basal internodes,subpanicle internodes,the height of gravitational center and the lodging rate decreased gradually as postponing N application;stem diameter,stem fresh weight,mechanical strength,potassium,silicon,lignin were the highest when N topdressing at booting stage,while the soluble sugar content reached the height at heading stage. Compared with the no N treatment,the stem mechanical strength of Mengyan 1 and Monte in topdressing at booting stage treatment increased by 62.29% and 42.72%,the stem resistance index increased by 59.18% and 45.58%,the forage yield increased by 40.85% and 19.22%,respectively. In conclusion,the content of potassium,silicon,soluble sugar and lignin in stem were closely related to the lodging resistance of oat. N topdressing at booting stage in favor of improving lodging resistance,forage and seed yield of oats.

Key words: Nitrogen, Topdressing stage, Oat, Stem strength, Lodging resistance, Forage yield

摘要： 为了明确不同追氮时期对燕麦茎秆形态学特征、理化物质构成的影响及其与倒伏性的关系，本研究以2个饲用燕麦（Avena sativa L.）品种为材料，在大田条件下设置不同追氮时期处理，测定燕麦植株形态学、茎秆理化特性、抗倒性和产量指标。结果表明：随追氮时期后移，2个品种株高、基部节间和穗下节间长度、重心高度和倒伏率呈降低趋势，植株茎粗、茎秆鲜重、机械强度、茎秆中钾、硅、木质素含量在孕穗期追氮达到最高，可溶性糖含量在抽穗期追氮达到最高。与不施氮处理比较，孕穗期追氮处理‘蒙燕1号’和‘蒙特’品种的植株茎秆机械强度提高62.29%和42.72%，茎秆抗倒指数分别提高59.18%和45.58%，干草产量分别提高40.85%和19.22%（P<0.05）。综上，茎秆钾和硅元素、木质素及可溶性糖含量与燕麦抗倒伏性密切相关，在孕穗期追施氮肥有利于提高燕麦抗倒性能并获得较高饲草和种子产量。

关键词: 氮肥, 追氮时期, 燕麦, 茎秆机械强度, 抗倒性, 饲草产量