Choosing Soybean Varieties from Yield Trials

Soybean [Glycine max (L.) Merr.] variety trials are conducted in many states and results are published from several years and locations of testing. These trials usually include a large number of varieties and locations that generate a large amount of agronomic data. Use of this information by growers and agricultural advisors to choose high‐yielding varieties is a difficult task. This study was conducted to determine which combination of locations and years was best to identify good‐yielding soybean varieties. We analyzed test results from soybean variety trials conducted by the Minnesota Soybean Breeding Project at three locations from 1980 through 1989. The results were grouped into combinations of years and locations and the varieties were ranked high to low on the basis of yield in each data set. High‐yielding groups of varieties were identified from each data set and their performance in the trials next year was determined. Choosing high‐yielding varieties on the basis of the multilocation data set resulted in highest yields in subsequent yield trials, and number of years in the multilocation data set had no statistical effect on subsequent yield of the chosen group of varieties when there were three or more varieties in the chosen group. Yields were about 5% higher than the mean of the entire test in subsequent tests for the High 1, High 2, and High 3 varieties. The yield of the group of varieties in next‐year trials decreased as the number of varieties in the group increased; highest yields next year occurred by choosing groups with one to three varieties from the 3 yr, three‐location data set. Therefore, a good production strategy for soybean growers is to choose a few high‐yielding varieties based on multilocation and multiyear data, but more emphasis should be given to multilocations than multiyears.