Hybrid Rank and Variance of Corn at Sites with Contrasting Humic Matter Content

Widely adapted, high‐yielding genotypes are most easily detected at sites in which differences among hybrids are large and where rankings are similar to the target environment. The objectives of this study were to determine if the relative yields, hybrid variances, and correlations with state‐wide means for corn ( Zea mays L.) hybrids differed among sites with low and high humic matter (HM) content. Five years of corn yield data from sites with contrasting HM content (0.032 vs. 0.059 g cm −3 ) located near Plymouth, NC, were collected. An analysis was performed for each year and maturity group which contained 12 to 48 hybrids. Mean yields averaged 12% (0.91 Mg ha −1 ) less at the high than low HM sites. Hybrid × HM interactions were significant ( P < 0.05) in about half of all trials but rarely involved changes in the rank order among hybrids, indicating that duplicating trials on the two soil types was not warranted. Despite lower yields at the high HM sites, ranges and hybrid variances were larger in these sites. Maximum yields were less affected by soil type than minimum yields, indicating greater stress tolerance in high‐yielding hybrids. A differential response among hybrids to some additional stress appeared to account for greater hybrid variances observed at the high HM sites. Correlations with state‐wide mean performance were greater for high than low HM sites. Locating test sites on soils with high HM content may be an efficient way to detect hybrids capable of producing high yields under a range of soil and climatic conditions.