Abstract: Our objective is to investigate the allelopathic effects of walnut(Juglans regia) root exudates. The root exudates of walnut trees were extracted with ethyl acetate and were identified by using the gas chromatography-mass spectrometry (GC-MS). The impact of the exudates investigated on the seed germination and seedling growth of turnip (Brassica rapa). The results indicated that the neutral, acidic, and alkaline components of the root exudates all inhibited the seed germination and seedling growth of turnip. The acidic component mainly included alkanes, alkenes, acidic, aromatic esters, alcohols, phenol, ketones, amines, quinones, and benzene. The neutral component mainly included alkanes, alkenes, acidic, aromatic esters, alcohols, phenols, terpenes, amines, naphthalene, quinones, and benzene. The alkaline component mainly included alkanes, alkenes, acidic, alcohols, phenols, amines, quinones, ketones, and benzene. This study provids important knowledge for improving and revealing the mechanisms of allelopathy effects of walnut trees.

Key words: allelopathy, GC-MS, root exudates, walnut (Juglans regia)