Technical Abstract: The cause of poor seed quality (germination) of soybean produced in the Early Soybean Production System in the midsouth U.S.A. is still not completely understood. Temperature, solar radiation, and soybean genotype may all be important factors involved. The objective of this research was to evaluate seed composition, mineral level, and nitrogen assimilation in high and low germinability soybean plant introductions in a full-sunlight environment (unshaded) and a low-light intensity environment (shaded). Shade netting was employed in field plots that reduced light intensity by about 50% and air temperature by about 10 ºF/6 ºC. A two-year field experiment was conducted on soybean accessions with high germinability (PI 587982A and PI 603723), low germinability (PI 80480 and PI 84976-1), and on soybean cultivars (DSR-3100 RR STS and Pella 86). Results showed that shade resulted in higher total oil, linoleic, and linolenic acids, and lower protein and oleic acid. Shade also resulted in lower nitrogen assimilation, leaf chlorophyll concentration, but higher seed total boron, iron, and nitrogen concentrations. Seed structural boron percentage was positively correlated with germination and protein. Structural boron percentage was higher under shade than under unshade in lines with higher germinability (PI 587982A and PI 603723). Our research demonstrated that light intensity combined with temperature can alter seed constituents. Higher germinability lines had higher germination rates and lower percentages of hardseededness, desirable traits for soybean seed.