Evaluation location: Illinois, United States
Accessions in maturity groups I through IV ranging from PI 507670 to PI 574486 were evaluated for descriptive characteristics, agronomic performance, and seed composition in 1994 and 1995 in Urbana, Illinois (Lat. 40o 00' N). Also included were cultivars in the same maturity groups, developed at public institutions in the United States and Canada, and released by early 1993. Tests were replicated once per year. Planting dates were May 20-21, 1994 and May 31-June 1, 1995. Plots were 4 m long with 4 rows 76 cm apart. They were trimmed to 3.2 m after maturity and the middle two rows harvested. Because of the difference in planting date, plants flowered about 5 days later in 1995 than in 1994. Accessions in maturity groups I and II also matured about 5 days later in 1995 than in 1994. Rainfall in August and early September of 1994 was much greater than in the same period of 1995, which may have contributed to a longer growing season for the later maturing accessions in 1994. A frost on September 22, 1995 cut the growing season short; therefore maturity dates from 1995 were not included if the accessions had not matured before the frost. Accessions in maturity group III matured about 10 days earlier in 1995 than in 1994 where data from both years were available. The seed composition data were collected at the USDA Northern Center for Agricultural Utilization Research in Peoria, IL. To obtain oil and protein percentages of the seeds with yellow seed coats, approximately 7 g of seeds were placed in a beaker and dried in a forced air oven for 3 hours at 130 C. The seeds were then transferred to 50 g bottles, sealed, and allowed to cool for 1 hour. Samples were then ground in a Varco electric dry food grinder and returned to the 50 g bottles. Seed samples were analyzed with an Infratec 1255 food and grain analyzer (Perstorp Analytical Company). Samples were scanned from 800 - 1100 nm. The analyzer was calibrated with at least 40 soybean samples having a protein range of 33 to 50 percent and an oil range of 12 to 24 percent. Protein and oil concentrations for samples with colored or very heavily mottled seed coats were obtained with the Kjeldahl procedure for protein and Butt extraction for oil. Fatty acid composition was obtained by gas liquid chromatography of the methyl esters. Seeds were ground in a small food grinder and stored at ?20 C until analyzed. Approximately 200 mg of ground sample was placed in a 25 ml vial, and 5 ml of sodium methoxide added in two 2.5 ml aliquots with an automatic syringe in such a way as to ensure mixing. (The sodium methoxide solution was prepared daily by adding 1 g of sodium metal to 100 ml of reagent grade methanol.) The sodium methoxide, ground sample suspension was allowed to stand for 45 minutes, after which 1 ml of 10 percent acetic acid solution was added, followed immediately by 10 ml of heptane (in two 5 ml aliquots). The samples were completely mixed after each reagent addition. This mixture was allowed to stand for several minutes so that the layers could separate. A 2-ml aliquot of the heptane layer was extracted for analysis in a Hewlett Packard model 6890 gas chromatograph equipped with a Model 6890 auto injector and flame ionization detector. Columns were 30 m by 0.32 mm capillaries coated internally with 5 percent diphenyl dimethyl siloxane. In the HP 6890, chromatography was isothermal and flow rates for helium, hydrogen, and air were 40, 40, and 450 ml min-1 respectively. The injection volume was 1 ?l with split ratios used, dependent upon the concentration of sample. Total analysis time was approximately 5 minutes. The integration, peak identification, data storage, and report printing were all performed by the Hewlett Packard Chemstation software and a modified Excel spreadsheet.