Abstract: Fifteen soybean germplasm resources were tested in this current research,they were collected from different areas of Southwest China.Correlation analyses between the main chemical constituents of the soybean and their field mildew resistance were conducted.The quantification of 12 isoflavones in soybean seeds were performed using an Agilent 1100-series high performance liquid chromatography(HPLC)system.The content of 19 fatty acids were measured using gas chromatograph-mass spectrometry(GC-MS).The soyasaponin,soluble polysaccharides and protein content were measured by UV-Vis spectrophotometry.From the result of our research,these fifteen soybean germplasms were divided into five groups.Soybean seed of C103 with high quality and better field mildew resistance,it can be used as high-quality soybean germplasm for further exploitation.Soybean seeds with higher mildew degree were rich in palmitic acid,translinoleic acid,erucic acid, etc.GL type of isoflavones(glycitein,glycitin,acetylglycitin,malonylglycitin)and aglycone were rich in the soybean germplasms with greater potential resistance effect for field mildew.Those isoflavones were methoxylation in the C-6 site of A-ring.

Key words: soybean, fatty acid, isoflavone, saponin, field mildew