Plant Breeding. 2019;1–10. wileyonlinelibrary.com/journal/pbr | 1 © 2019 Blackwell Verlag GmbH 1 | INTRODUCTION Forage maize is a primary energy feed for dairy cows. In addition to stover digestibility, the degradation of starch in the rumen is another important criterion of forage maize quality. Starch is the main compo‐ nent of corn grain, accounting for approximately 75% of the dry matter yield of the grain, and is the predominant energy source in the dairy industry (Ferraretto & Shaver, 2012). Starch degradation characteris‐ tics largely determine the feeding value of forage maize (Canizares et al., 2011). More than 85% of starch is present in corn endosperm, and genes associated with endosperm starch biosynthesis were identified, such as amylose extender (ae), brittle2 (bt2), shrunken2 (sh2) and sug‐ ary1 (su1) (Bae, Giroux, & Hannah, 1990; Georgelis, Braun, Shaw, & Hannah, 2007; Goldman, Rocheford, & Dudley, 1993; Hannah et al., 2001; James, Robertson, & Myers, 1995; Martin & Smith, 1995). Starch is the primary carbohydrate energy source for seed ger‐ mination. Starch can be degraded by hydrolysis or phosphorolysis with enzymes including α‐Amylase, β‐Amylase and debranching enzymes (Scheidig, Fröhlich, Schulze, Lloyd, & Kossmann, 2002; Subbarao, Datta, & Sharma, 1998). Starch is also an important sub‐ strate to ensure rumen fermentation, resulting in a large amount of propionic acid, which is an important source of energy. Starch degradation of maize kernels in rumen fluid is mainly influenced by starch content, composition of the starch (amylose, amylopec‐ tin) and physical properties of the starch (Stevnebø, Sahlström, & Svihus, 2006). Depending on the usage, performance and animal feeding level of forage maize, different biodegradabilities of the rumen are desirable. Understanding the genes related to starch degradation and their characteristics is helpful for genetic im‐ provement of silage quality. Received: 22 October 2018 | Revised: 22 January 2019 | Accepted: 17 February 2019 DOI: 10.1111/pbr.12699 ORIGINAL ARTICLE QTL mapping of improving forage maize starch degradability in European elite maize germplasm Pengfei Leng 1 | Milena Ouzunova 2 | Matthias Landbeck 2 | Gerhard Wenzel 3 | Thomas Lübberstedt 4 | Birte Darnhofer 5 | Joachim Eder 5 1 Department of Crop Genomics & Genetic Improvement, Biotechnology Research Institute, Chinese Academy of Agricultural Sciences, Beijing, China 2 KWS SAAT SE, Einbeck, Germany 3 Department of Agronomy and Plant Breeding, Technical University of Munich, Freising‐Weihenstephan, Germany 4 Department of Agronomy, Iowa State University, Ames, Iowa 5 Bavarian State Research Center for Agriculture, Freising‐Weihenstephan, Germany Correspondence Birte Darnhofer and Joachim Eder, Bavarian State Research Center for Agriculture, Freising‐Weihenstephan, Germany. Emails: Birte.Darnhofer@LfL.bayern.de; Joachim.Eder@lfl.bayern.de Funding information German Federal Ministry of Education and Research, Grant/Award Number: EUREKA E 2386 Communicated by: Jens Léon Abstract Improving maize starch content is of great importance for both forage and grain yield. In this study, 13 starch degradability traits were analysed including percentage of the seedling area, floury endosperm, hard endosperm of total grain area, percentage of the floury endosperm surface and vitreousness ratio surface hard: floury endosperm surface, etc. We mapped quantitative trait loci (QTL) in a biparental population of 309 doubled haploid lines based on field phenotyping at two locations. A genetic linkage map was constructed using 168 SSR (simple sequence repeat) markers, which covered 1508 cM of the maize genome, with an average distance of 9.0 cM. Close phenotypic and genotypic correlations were found for all traits, and were all statisti‐ cally significant ( p = 0.01) at two locations. Major QTL for more than two traits were detected, especially in two regions in bins 4.05–4.06 and 7.04–7.05, associated with 13 and 9 traits, respectively. This study contributes to marker‐assisted breeding and also to fine mapping candidate genes associated with maize starch degradability. KEYWORDS endosperm, forage maize, gas production, QTL analysis, starch degradability