Growth and Development of Soybean Isolines that Differ for Maturity

AbstractIsolines for maturity within a common background may be useful in research that attempts to determine the effect of maturity group adaptation on soybean [Glycine max (L.) Merr.] growth or yield. Although the effects of maturity genes on soybean phenology have been studied extensively, little is known about their effects on other soybean characteristics. Field experiments were conducted near Columbia, MO, in 1991 and 1992 to determine the effects of three major maturity genes on growth and development of soybean. Four near‐isogenic strains (isolines) were replicated four times in a completely randomized design: L71‐920 (e1e2e3), Clark (e1E2E3), L74‐441 (E1E2e3), and L67‐1474 (E1E2E3). Vegetative and reproductive characteristics were recorded for five plants within each plot. Late‐maturing isolines were taller and had more leaves than early‐maturing isolines, but stem growth and leaf initiation rates were similar. Late‐maturing isolines produced more flowers and pods because they had more nodes than early‐maturing isolines. Late‐maturing isolines produced more than 25% of total yield on branches, whereas early‐maturing isolines produced approximately 10% of total yield on branches. Because the isolines used in this study had consistent differences for plant phenology, they can be useful components of experiments that include maturity as a factor. However, changes in phenology also changed plant morphology.