Better Soybean Variety Selection Using Relative Maturity Probabilities and Yield Potential.

Soybean cultivar selection should be site-specific. We determined the probability of a relative maturity (RM) to yield similar or better than the other RM by analyzing the yield data of both full-season and double-crop soybean from Virginia Official Variety Tests (OVT) that were conducted across five locations in Virginia from 2006 to 2015. Soybean RM ranged from late maturity group (MG) III to late MG V for full-season and early MG IV to late MG V for double-crop. Full-season and double-crop soybean, yields were affected by RM for each year at each location with few exceptions. The probability of any given RM to yield more or the same than other RM was similar to the yield balance results, with only minor deviations. In general, earlier RM yielded more as one moves north and west (shorter growing season) and later RM yielded more as one moves south and east (longer growing season), but there were exceptions. Exceptions included early- and mid-IV cultivars having greater yield balance and probably of yielding as well or more at Painter, our farthest east location; and MG IV cultivars yielding more than other cultivars at Warsaw, which represents the second greatest latitude. With double-crop systems, the optimum RM shifted slightly to later maturing cultivars unless those cultivars were injured by early frosts. Overall, late-IV cultivars yielded well at all locations. These results allow farmers to confidently choose a MG with high probability of the greatest yield for both cropping systems across their farming locations in Virginia. We also used five years of OVT data to predict the yield of cultivars from different MG in 1350, 2700, and 4050 kg ha^-1 environments across five locations. Yields of each cultivar were regressed against the average yield of all cultivars tested at that location. If the slope of this regression was significantly greater or less than 1.0, we termed this cultivar a "racehorse" or "mule", respectively. If the slope was equal to 1.0 but yields were greater at all yield potentials, we termed those cultivars "quarter horses" or "nags", respectively.