Dry Matter Accumulation and Seed Yield of Determinate and Indeterminate Soybeans1

Authors:
  • JBJ. S. Beaver
    J. S. Beaver
  • RCR. L. Cooper
    R. L. Cooper
  • RMR. J Martin
    R. J Martin
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Abstract
Some determinate soybean [Glycine max(L.) Merr.] cultivars developed for the northern USA yield as well as the conventional indeterminate cultivars. The principal objective of this research was to compare morphological and physiological traits of the determinate cultivar ‘Elf’ with the indeterminate cultivar ‘Williams’ and a determinate isoline of the cultivar ‘Clark.’ Field experiments were conducted at Urbana, IL in 1976 on a Flanagan silt loam (fine, montmorillonitic, mesic Acquic Argiudoll) and at Wooster, OH in 1981on a Wooster silt loam (fine‐loamy, mixed, mesic Typic Fragiudolf). Plants from weekly samples taken from the 5th week after emergence until R7 were separated into leaflets, petioles, main stems, branches, pods from main stems, and pods from branches. Patterns of dry weight accumulation for the plant parts were estimated using regression techniques. Estimates of seed yield components were obtained from an adjacent set of experiments. The genotypes accumulated leaf, petiole, and total dry weight in a similar fashion. Williams accumulated more main stem dry weight than the determinate genotypes. However, the difference in main stem dry weight was partially compensated by a greater branch dry weight of the determinate genotypes. Although Williams produced more main stem nodes, the determinate genotypes set as many pods on the main stems as Williams. The determinate genotypes produced a greater number of pods and more seed weight from branches than Williams. In 1976, Elf accumulated reproductive dry weight at a greater rate than Williams or Clark (dt1). The apparent harvest index of Elf was greater than the other genotypes during both years. Seed yields did not differ in 1976, whereas the determinate genotypes yielded slightly less than Williams in 1981.