Abstract

To test whether the semi-determinate stem termination trait in soybean [Glycine max (L.) Merr.] would influence seed yield or other agronomic traits, a large number of near-isogenic, F₄ and F₅-derived semi-determinate and indeterminate lines from three crosses were developed and tested in 35 and 70-cm rows during 1974 and 1975.

Stem termination type had no effect on seed yield, regardless of genetic background and row spacing. On the average, semi-determinates were 16 cm shorter and had two fewer nodes. In late, very tall, isoline pairs, they tended to lodge less. Semi-determinates averaged 0.5 to 3 days earlier in time of maturity, depending upon genetic background, but earliness did not result in lower yield.

We conclude that, with the semi-determinate stem termination type, it is possible to have soybean lines that are earlier maturing, shorter, and, under conditions of luxuriant growth, perhaps with lesser lodging than indeterminates with no sacrifice in yield.

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