When choosing summer-annual forage varieties based solely on yield, it's okay to use data from dryland research, even if the crop will be irrigated. But don't use irrigated yield data to pick dryland varieties, say Noble Foundation researchers.
In their trials, the highest-yielding varieties of sorghum, sudan, sorghum-sudan crosses and pearl millet without irrigation also were in the highest-yielding irrigated group. But several varieties not in the top dryland group placed higher when irrigated.
They also found that, when irrigated, brown midrib (BMR) varieties had significantly better quality than non-BMR varieties, but not when rain-fed. Conversely, photoperiod-sensitive (PS) varieties had higher quality than conventional ones on dryland, but not under irrigation. They were in the highest-yielding group when irrigated, but not under dryland conditions. The BMR varieties were not in the top-yielding group under either water regime.