Effect of Plant Height and Flowering Date on Seed Yield of Determinate Soybean

Abstract

An experiment was conducted to study the value of plant height and time of flowering in improving yield of determinate soybean [Glycine max (L.) Merr.) grown in the northern USA. Eight crosses were made among 10 determinate plant introductions. Twenty F2 families representing four plant types: tall, early flowering; tall, late flowering; short, early flowering; and short, late flowering were identified in the F3 generation for each of Maturity Groups I, II, and III. They were yield tested in 1985 and 1986 in a Flanagan silt loam (Aquic Argiudoll) at Urbana, IL. Seed yield was significantly affected by time of flowering in all three groups. Early flowering families outyielded the late‐flowering families by 7, 28, and 14% in Groups I, II, and HI, respectively. The short, early‐flowering type had the highest mean yield and highest yielding individual families for all three Maturity Groups. The highest yielding F2 families were taller than currently grown determinate cultivars and yielded approximately 80% of ‘Gnome’ and ‘Hobbit’. These data indicate that time of flowering is relatively more important than plant height in determining seed yield of determinate soybean in Maturity Groups I through III.