Breeding effects on the genotype x environment interaction for yield of bread wheat grown in Spain during the 20th century

This study evaluates the changes caused by breeding in the genotype x environment interaction of the bread wheat varieties most widely cultivated in Spain during the 20th century. A set of 27 varieties was tested in 8 environments representative of the bread wheat growing areas in the country. Minimum temperature and thermal time from sowing to heading were the main environmental traits determining genotype x environment (GE) interactions for yield. Landraces were the least productive and showed specific adaptation to environments with low minimum temperatures before heading and high relative air humidity after heading. Yield consistency was low in landraces due to large environmental effects on the number of spikes and grain weight. Old-bred varieties (released between 1945 and 1955) were the first step towards breeding for wide adaptation due to the lower dependence of their final spike number and grain weight on water availability during grain filling. Differences in the adaptation pattern of the varieties introduced since the 1960s were caused by their growth habit. Winter types were more widely adapted than spring ones, mostly because they had a more consistent number of grains per spike. Grain weight of winter varieties was enhanced in environments with high relative humidity during grain filling. Spring varieties had more grains per spike in environments with high minimum temperatures and thermal time before heading. The number of grains per spike was the yield component that most closely followed the pattern of adaptation observed for grain yield. (C) 2011 Elsevier B.V. All rights reserved.