Genotype × environment interaction amongst spring barley lines grown at sites in the northern and southern hemispheres

Summary Measurements and scores for juvenile plant habit, time to ear emergence, plant height, leaf diseases and 1000 kernel weight were recorded on 123 lines of spring barley grown at Palmerston North, (40°S) New Zealand, and at Cambridge, (52°N) England. The material was grown at both sites from F₄ to F₇.For juvenile habit, time to ear emergence, plant height and 1000 kernel weight highly significant correlations were found between sites and seasons though few accounted for more than 50 per cent of the variation. There was no evidence of closer correlation between seasons within sites than between sites and seasons, and it was concluded that selection at either site should be equally effective.Analysis of yield performance over sites and seasons within sites revealed large effects due to genotypes and seasons within sites but small effect due to sites. Large interactions were found between genotypes and sites but the genotypes × seasons within sites effect was relatively small; better agreement was found in relative yields between seasons within sites than between sites, so that yield performance in one country was a poor indication of potential performance in the other country.The implications of these results for the use of a selection nursery in New Zealand are discussed.