Yield Stability of Soybean Mixtures and Multiple Pure Stands1
- A. K. Walker and
- W. R. Fehr2
The objective of our study was to determine the number of high-yielding soybean [Glycine max (L.) Merr.] cultivars that should be grown in mixtures or in pure stands to obtain high yield and stability of production across environments. Eighty entries prepared from 28 high yielding pure lines with a 10-day range in time of maturity were evaluated during 1975 and 1976 at six locations in Iowa. Yields in the 12 environments ranged from 11.1 to 39.2 q/ha. The entries, which included 14 of the 28 pure lines and six mixtures each for 2 to 10, 12, and 14 components, represented 12 levels of heterogeneity.
There were no significant differences in yield between the mixtures and the mean of their components grown in pure stands (multiple pure stands). Regression of entry yields on an environmental index indicated that none of the pure lines, mixtures, or multiple pure stands had regression coefficients significantly different from each other or from unity. Average mean squares for deviations from regression were slightly smaller for mixtures than multiple pure stands and tended to decrease until mixtures had eight or more components. It was not possible, however, to define precisely the number of pure lines needed for stable production because mean squares for deviations from regression were more variable within than among levels of heterogeneity. Stable production depends on the particular cultivars or mixtures chosen as much as on the number involved. The choice between mixtures and multiple pure stands would depend on the yield of cultivars resistant to sporadic pest and soil problems, length of harvesting period desired, and the need to save pure seed.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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