Evaluation location: Mississippi, United States
The purpose of this research was to identify soybean germplasm possessing positive traits affecting high seed germinability for seed produced under high-temperature environments, such as in the early soybean production system (ESPS) of the midsouthern United States. Seed was produced in the ESPS for 486 U.S. plant introductions (PI), 25 ancestral lines of U.S. cultivars, and four U.S. cultivars at Stoneville, MS, in 2002 and 2003. Standard and accelerated aging germination percentages, hardseededness, seed coat wrinkling, and incidence of P. longicolla were estimated for each line. Accessions having a mean standard field germination of greater than or equal to 90%, less than 10% hard seed and P. longicolla infection, and less than or equal to 10% wrinkled seed coat were considered "T" (High germinability in high temperature environments); between 80 and 89% standard field germination, less than 10% hard seed and P. longicolla infection, and less than or equal to 10% wrinkled seed coat were considered "I" (Intermediate germinability in high temperature environments); and the rest "S" (Poor germinability in high temperature environments).