同过测定广玉兰（Magnolia grandiflor .Lima）叶的乙醇提取物以及不同溶剂萃取层对植物病原真菌的抑菌活性，寻找广玉兰叶中的农用活性物质，为其综合开发利用提供科学依据。采用菌丝生长速率法测定了广玉兰叶乙醇提取物对8种植物病原菌的抑制作用。结果表明，当供试浓度为1.0 mg/ml时对苹果腐烂病菌(Valsa mali)、白菜黑斑病菌(Alternaria brassicicola)的抑菌率比较高，抑菌率分别为81.4%和52.1%。当供试浓度为5.0 mg/ml时，对小麦赤霉病菌(Gibberella zeae)、棉花枯萎病菌(Fusarium oxysporum f.sp.vasinfectum)和苹果轮纹病菌(Physalospora piricola nose)的抑菌率也比较高，均为50.0%以上。乙醇提取物对苹果腐烂病菌和白菜黑斑病菌EC50分别为0.04 mg/ml和1.20 mg/ml。广玉兰叶乙醇提取物的不同极性溶剂萃取物中正己烷层与乙酸乙酯层的抑菌活性较高，EC50分别为0.03 mg/ml和0.11 mg/ml。活性物质主要集中于正己烷和乙酸乙酯萃取部分，是进一步研究的重点。

In order to discover the agricultural activity and fungicidal ingredient in the leaves of Magnolia grandiflora Lima and provide scientific proofs of its exploitation and utilization, antifungal activity of the extracts from leaves of Magnolia grandiflora. Lima with ethanol and different solvents were studied. Using a mycelial growth method, the fungistasis of the extracts with ethanol against eight agricultural fungi were investigated in this study. The results showed that the extracts have strong antifungal activity against the tested pathogenic fungi. The inhibition rate of 81.4% and 52.1% with the concentration of 1.0 mg/ml, against Valsa mali and Alternaria brassicicola, respectively. With the concentration of 5.0 mg/ml, the inhibition rate of more than 50% against Gibberella zeae, Fusarium oxysporum f.sp.vasinfectum and Physalospora piricola nose. The EC50 of ethanol extracts against V.mali and Alternaria brassicicola were 0.04 mg/ml and 1.20 mg/ml. The ethanolic extract was fractionated using solvents of increasing polarity, the n-hexane and ethyl acetate fraction had stronger antifungal activities than that of extracts by solvents n-butanol and water. The EC50 of n-hexane and ethyl acetate fraction against V. mali was 0.03 mg/ml and 0.11 mg/ml, respectively. These indicated that most of the activity components were distributed in the n-hexane and ethyl acetate fraction, and the n-hexane and ethyl acetate partition would be acted as the emphases in the further study.