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Wheat (Triticum aestivum L.) grain yield is predicted to decrease in the future because of an increase in air temperature globally. To clarify the effects of the vernalization response gene in wheat to warmer winters, we compared dry matter production and grain yield between spring wheat ‘Asakazekomugi’ and its winter-type near-isogenic line (NIL) carrying different alleles of the vernalization response gene Vrn-D1 under early-, standard-, and late-sowing conditions. Under early-sowing conditions, dry matter production of the NIL carrying the winter allele of Vrn-D1, named Asa (Vrn-D1b), exceeded that of ‘Asakazekomugi’ from mid-March (after stem elongation in Asa (Vrn-D1b)) when the temperatures rose. Tiller number and leaf area index under early-sowing conditions were consistently higher in Asa (Vrn-D1b) than in ‘Asakazekomugi’ from mid-March onward. It was suggested that the early-sown ‘Asakazekomugi’ could not effectively absorb solar radiation to produce dry matter because of the acceleration of stem elongation caused by the Vrn-D1 gene during the cold season. The grain yield of Asa (Vrn-D1b) with early sowing was higher than with standard sowing. In contrast, the grain yield of ‘Asakazekomugi’ was lower in the early-sown crop than in the crop sown at the standard date. These results suggested that the higher grain yield of Asa (Vrn-D1b) than that of ‘Asakazekomugi’ under early-sown conditions could be due to Asa (Vrn-D1b) maintaining high dry matter production after the jointing stage by suppressing acceleration of growth caused by warm conditions after sowing. Abbreviations CGR: crop growth rate; HI: harvest index; LAI: leaf area index; NIL: near-isogenic line; SNP: single-nucleotide polymorphism

For genetic mapping of major photoperiod (Ppd-B1) and vernalisation (Vrn-D1) genes in wheat, four segregating populations were employed. For this purpose, AFLP and SSR were chosen as molecular techniques. The use of different populations carrying the same gene enabled to answer the crucial question in marker assisted selection (MAS) whether the markers found in a specific cross can be also applied in different crosses. Furthermore, a simple method for scoring the presence of Ppd-B1 gene was also developed by converting a co-segregating AFLP to a simple PCR marker. Das Ziel der Arbeit war die genetische Kartierung der Gene Ppd-B1 und Vrn-D1, welche für die Reaktion auf die Photoperiode bzw. Vernalisation in Weizen wichtig sind. Hierzu wurden vier spaltende Nachkommenschaften mit AFLP- und SSR-Markern kartiert. Die Nutzung verschiedener Populationen, die für die gleichen Gene segregieren, erlaubte die Beantwortung der Frage ob die identifizierten Marker populationsspezifisch sind oder populationsübergreifend zur Marker-gestützten Selektion (MAS) genutzt werden können. Darüber hinaus wurde eine einfache Methode zur Überprüfung der Anwesenheit des Ppd-B1 Gens entwickelt.