Genotypic Interaction of Early Maturity Soybean with Row Spacings
- W. V. Hugie and
- J. H. Orf
Previous research has demonstrated that soybean [Glycine max (L.) Merr.] seed yields in the northern USA generally increase as row spacing is reduced. However, studies examining the consequences of a genotype ✕ row spacing interaction for seed yield on selection practices used to identify superior lines for use in wide and narrow row spacings have reported conflicting results. The objectives of this study were to: (i) examine the genotype ✕ row spacing interaction in preliminary breeding material of early maturity soybean; (ii) determine whether early maturing determinate genotypes respond similarly to indeterminate genotypes for yield in wide and narrow rows; and (iii) determine if information from whole plots or from parts of samples from one row spacing could be used to predict performance of genotypes in another row spacing. Two hundred and seventy-six indeterminate and determinate genotypes of Maturity Groups 0, I, and early II were evaluated in six yield tests at two locations over 2 yr. Genotypes were planted in 25- and 76-cm row spacings. Plant samples were taken from a 0.76 m2 area of each plot to examine traits that might be useful in identifying superior genotypes for either row spacing. A genotype by row spacing interaction for seed yield was observed in four of the six tests. The determinate genotypes responded similarly to the indeterminate genotypes for yield in both row spacings. Of the traits measured, selection for mean seed yield was the most efficient characteristic in identifying superior yielding genotypes for use in either row spacing even if testing was limited to one row spacing. Generally, narrow rows were superior or equivalent to wide rows for identifying the best genotypes from preliminary yield tests for further testing in either row spacing.
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