Abstract: In order to explore the effects of rhizobium, nitrogen application rate, and fertilization frequency on the production rate, the aboveground biomass and fiber content of ‘Caoyuan No. 3’ hybrid alfalfa (Medicago varia Martin. ‘Caoyuan No.3’), the experiment adopted a completely random design, set whether to inoculate rhizobia, five kinds of nitrogen application rate (600 kg·hm^-2, 750 kg·hm^-2, 900 kg·hm^-2, 1 050 kg·hm^-2, 1 200 kg·hm^-2) and three fertilization frequency (4 times, 6 times, 8 times). Growth rate, above-ground biomass, cellulose content, and other indicators were analyzed. The results showed that, rhizobium inoculation promoted the last growth of alfalfa and reduced the contents of acid detergent fiber and neutral detergent fiber. Under the experimental conditions of this test, when 900 kg·hm^-2 rhizobia and nitrogen was applied for 6 times, the maximum aboveground biomass was obtained.

Key words: Nitrogen Fertilizer, Rhizobium, Alfalfa, Aboveground biomass, Fiber content

摘要： 为探究根瘤菌、施氮量与施肥频率三因素对‘草原3号’杂花苜蓿（Medicago varia Martin.‘Caoyuan No.3’）生长及纤维含量的影响，本研究采用完全随机区组设计，设置有无接种根瘤菌、5种施氮量（600 kg·hm^-2，750 kg·hm^-2，900 kg·hm^-2，1 050 kg·hm^-2，1 200 kg·hm^-2）与3种施肥频率（4次、6次、8次）三因素试验，测定生长速率、地上生物量、纤维素含量等指标。结果表明：接种根瘤菌会促进第三茬苜蓿的生长，而使酸性洗涤纤维和中性洗涤纤维含量下降。本试验条件下，接种根瘤菌，施氮量为900 kg·hm^-2，施肥频率为6次时，地上生物量最大。

关键词: 氮肥, 根瘤菌, 苜蓿, 地上生物量, 纤维