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Genetic gains in quality traits were assessed in grain samples from 4 field experiments involving 16 bread wheat varieties representative of those most widely cultivated in Spain during the 20th century. The allelic composition at three glutenin loci ( Glu-A1 , Glu-B1 , and Glu-D1 ) was obtained by PCR-based DNA markers and published references. From 1930 to 2000 grain protein content decreased by −0.030% y −1 , or in relative terms by −0.21% y −1 , but the protein produced per hectare increased by 0.39% y −1 . Alveographic tests revealed significant changes in dough rheological properties. Dough strength ( W ) and tenacity ( P ) increased at relative rates of 1.38% y −1 and 0.99% y −1 , respectively, while dough extensibility ( L ) decreased by −0.46% y −1 , resulting in an increase of 1.45% y −1 in dough equilibrium ( P / L ). The rise in protein quality could be related to the replacement of the null allele by subunits 1 or 2* at Glu-A1 and the prevalence of subunits 7 + 8 and 5 + 10 at Glu-B1 and Glu-D1 loci, respectively, in the most recent varieties. Dough extensibility was affected by water input during the crop cycle, this relationship being partially explained by the presence of the 5 + 10 HMW glutenin subunit. Fermentation tolerance was improved in the most modern varieties. Collapse during fermentation was avoided only in doughs with a W ≥ 159 J × 10 −4 and a P / L ≥ 0.56 mm H 2 O mm −1 , levels achieved by most of the modern varieties. The over-strong and unbalanced rheological properties of some modern varieties resulted in highly porous doughs, and no clear advances in dough maximum height during fermentation were attained. [ABSTRACT FROM AUTHOR]

Abstract: This study evaluates the changes caused by breeding in the genotype×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×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. [Copyright &y& Elsevier]