Abstract: In order to investigate the effects of different rhizobial strains on nitrogen fixation,growth and nutrient composition of 'Mengnong No.1' (Trifolium ambiguum Bieb. 'Mengnong No.1') by tumor formation,five rhizobial strains isolated from Mengnong Clover No.1 in the experimental field of Qinghai University were selected (No.1,No.2,No.3,No.5,and No.9),which were then inoculated with test material for inoculation treatment,with no inoculation as control (CK). After the inoculation for 60 days,10 plants were randomly selected from each treatments,and the growth phenotypic indexes,nutrient composition,nitrogen-fixing enzyme activity of the plants were determined,and the microstructure of the dominant strains was observed. The main results were as follows:(1) Inoculation with different strains of bacteria improved the growth phenotypes and other indicators of plants;the height of plants in each treatment group increased by 53.28%,25.61%,5.02%,169.78% and 71.00%,respectively. (2) Strain No. 5 had the best overall performance,with plant height and crude protein (CP) content increasing by 169.78% and 37.99%,acid detergent fiber (ADF) and neutral detergent fiber (NDF) decreasing by 45.34% and 54.11%,respectively,compared with the control;and the rhizobia were more proliferated in rhizoblasts and the number of rhizoblasts that had been infected was also higher. (3) The strain No. 3 had the strongest nitrogen fixing enzyme activity of 10.21 μmol·(g·h)^-1,followed by strain No. 5 with an activity of 9.16 μmol·(g·h)^-1.

Key words: Mengnong No. 1, Rhizobium inoculation, Nodule nitrogen fixation, Principal component analysis

摘要： 为探究不同根瘤菌菌株对'蒙农三叶草1号'(Trifolium ambiguum Bieb.' Mengnong No.1')结瘤固氮、生长及营养成分的影响，选择5种分离自青海大学试验田内'蒙农三叶草1号'的根瘤菌(No.1，No.2，No.3，No.5，No.9)，分别与供试材料进行接种处理，以未接种为对照(CK)。接种60 d后，各处理随机选取10株，分别测定植株的生长表型指标、营养成分、固氮酶活性，并对优势菌株进行显微结构的观察。结果表明：接种不同菌株后，均会改善植株的生长表型等指标。各处理组植株的株高较CK分别显著提高了53.28%，25.61%，5.02%，169.78%和71.00%(P＜0.05)；5号菌株综合表现最优，株高和粗蛋白(Crude protein，CP)含量分别较对照增长了169.78%和37.99%，差异显著(P＜0.05)；酸性洗涤纤维(Acid detergent fiber，ADF)和中性洗涤纤维(Neutral detergent fibre，NDF)分别比对照下降45.34%和54.11%，差异显著(P＜0.05)；根瘤菌在根瘤细胞中定殖较多且被侵染的根瘤细胞数目也较多；3号菌株固氮酶活性最强，达到了10.21 μmol·(g·h)^-1，其次为5号菌株，活性为9.16 μmol·(g·h)^-1。

关键词: 蒙农三叶草1号, 接种根瘤菌, 结瘤固氮, 主成分分析