Abstract: Based on the observational field data of soybean from 2001 to 2009, the effect of meteorological factors and biological factors in different soybean growth stages on soybean yield was analyzed using methods of a correlation analysis and a path analysis. The results show that the effect of meteorological factors in the different growth period on soybean yield differs. Among all factors, the correlation coefficient between the mean air temperature and soybean yield is highest and reaches 0.90 in the flowering and bearing pod stages, then that between precipitation and soybean yield is 0.71 in sowing date-emergence stage. Furthermore, relative humidity and sunshine duration in the bearing pod stages to seed-filling period, biomass in the branding stage and leaf area in the flowering stage could also affect the soybean yield (r>0.5). The path analysis indicates that leaf area in the flowering stage is the main and direct influencing factor to soybean yield, while the greater effect of temperature and precipitation on the yield is produced by the indirect effect of biomass and leaf area. Relative humidity and sunshine duration in the bearing pod stages to seed-filling stage have large influence on soybean yield. A regression equation is established by coupling the meteorological factors and biological factors, which could simulate well soybean yield (R²=0.99).

Key words: Path analysis, Soybean, Yield, Meteorological factor, Leaf area, Biomass