AGRONOMIC PERFORMANCE AND ECONOMIC VALUE OF HIGH-SEED-PROTEIN SOYBEAN

The long-term trend in relative value of soybean [Glycine max (L.) Merr.] protein and oil is toward greater value of protein, thus furthering interests in the potential for increasing seed protein concentration in soybean. If a change in U.S. soybean breeding strategy for improving seed protein levels is required, it should be based on sound economic and biological principles. This research was conducted to: (i) develop high-protein soybean germplasm adapted to Mid-Atlantic latitudes; and (ii) compare agronomic performance, economic value, and stability of performance of resulting genotypes with that of normal-protein soybean cultivars. Fifty-two high-protein soybean lines were developed and evaluated in field tests in 1988 and 1989. Seven of the highest yielding high-protein lines, seven advanced commercial lines, and 'Essex' were evaluated in 11 field tests in 1990. All lines in all tests were evaluated for seed protein and oil, seed yield, and other agronomic characters. High-protein lines were: (i) superior for seed protein concentration and approximate processed value (APV) per bushel; (ii) inferior for seed yield and oil concentration and APV per acre; and (iii) less able to use environmental yield potential, with a decreased seed protein and increased seed oil, as compared with commercial cultivars. Extensive regional testing, including environments with very high seed yield potential, will be required to more precisely describe the biological and economic trade-offs for high-protein vs. normal-protein soybeans.