Late-planted soybean [Glycine mau (L.) Merr.] yields are usually lower
than fun-season soybean yields. Indeterminate growth habit may be sup
erior to the traditional determinate growth habit for late planting in
the southeastern USA. The objective of our study was to determine the
effect of determinate and indeterminate growth habit genes on yield c
omponents of late-planted near-isogenic lines of soybean. Twenty-three
determinate and 23 indeterminate near-isogenic lines (near-isolines)
of soybean from three populations were compared in the field at Brewto
n, Tallassee, and Shorter, AL, in 1991 and 1992. Determinates had lowe
r lowest-pod heights, more mainstem branches per plant, and more two-s
eeded pods than indeterminates. Growth habit did not affect total pods
per plant, mainstem or branch pods per plant, seeds per plant, seed m
ass, or number of three-seeded pods per plant. The growth habit x popu
lation and growth habit x location interactions were significant for m
ost traits, but the growth habit x year interactions were nonsignifica
nt or small. Number of mainstem pods was the only yield component corr
elated with yield (r = 0.36*). we conclude that (i) growth habit gene
s have little consistent effect on most yield component traits, (ii) g
rowth habit effects are site- and population-specific in the southeast
ern USA, and (iii) seed yield is not correlated with yield component t
raits in late-planted soybean.