Suchergebnisse

7 Pags., 3 Tabls., 1 Fig. ; S-1-progeny recurrent selection has proved effective improving the performance per se and the general combining ability (GCA) of maize (Zen mays L.) synthetic populations. Two maize synthetics, EZS1, a flint-type of Span ish origin, and EZS2, a dent population of North American origin, were produced al Zaragoza, Spain, and subjected to two cycles of S-1 recurrent selection for increased grain yield and reduced lodging and grain moisture. Our objectives were i) to assess the effect of S-1 recurrent selection on the heterotic behaviour of these synthetics, and) to evaluate the changes in combining ability after selection using as testers the populations themselves and three diverse inbred lines. The entries from a diallel mating design of the three cycles (0,1, and 2) of the two populations were tested in five environments. Testcrosses involving the three selection cycles of both synthetics and three diverse inbred testers were evaluated in three environments. Selection in both synthetics resulted in more productive populations, with less lodging, and no important negative responses in other agronomic trails. Improvements were less evident in the crosses of the populations, with significant GCA change only in EZS2 for lodging. Gains due to selection for grain yield in both synthetics and for lodging in EZS2 were significant, but the gains were not consistent across testers. Selection was effective in improving the populations per se. and the best testcrosses were not significantly different from the hybrid checks used for comparison. ; The senior author thanks the Basque Government for a graduate research assistant-ship. ; Peer reviewed

31 Pags.- 4 Figs.- 6 Tabls. © The Author(s) 2021. This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. ; The optimization of phenology is a major goal of plant breeding addressing the production of high-yielding varieties adapted to changing climatic conditions. Flowering time in cereals is regulated by genetic networks that respond predominately to day length and temperature. Allelic diversity at these genes is at the basis of barley wide adaptation. Detailed knowledge of their effects, and genetic and environmental interactions will facilitate plant breeders manipulating flowering time in cereal germplasm enhancement, by exploiting appropriate gene combinations. This review describes a catalogue of alleles found in QTL studies by barley geneticists, corresponding to the genetic diversity at major flowering time genes, the main drivers of barley phenological adaptation: VRN-H1 (HvBM5A), VRN-H2 (HvZCCTa-c), VRN-H3 (HvFT1), PPD-H1 (HvPRR37), PPD-H2 (HvFT3), and eam6/eps2 (HvCEN). For each gene, allelic series, size and direction of QTL effects, interactions between genes and with the environment are presented. Pleiotropic effects on agronomically important traits such as grain yield are also discussed. The review includes brief comments on additional genes with large effects on phenology that became relevant in modern barley breeding. The parallelisms between flowering time allelic variation between the two most cultivated Triticeae species (barley and wheat) are also outlined. This work is mostly based on previously published data, although we added some new data and hypothesis supported by a number of studies. This review shows the wide variety of allelic effects that provide enormous plasticity in barley flowering behavior, which opens new avenues to breeders for fine-tuning phenology of the barley crop. ; This research was supported by the contract "Iberia region hybrid barley variety development and understanding effects of adaptation genes in hybrids", between CSIC and Syngenta Crop Protection AG, which included funding for MFC PhD scholarship, and by grants AGL2016-80967-R and PID2019-111621RB-I00 (Ministry of Science and Innovation of Spain), SUSCROP ERA-NET project BARISTA, PCI2019-103758, and the Government of Aragón (group A08_20R). ; Peer reviewed

3 Pags.- 2 Figs. This is an open access article distributed under the terms of the Creative Commons CC BY license, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. ; Dixon et al. (2020) report a novel role for the TB1 transcription factor gene in wheat, controlling plant height. This gene and its orthologues have long been known to affect branching in a number of crops and plant species. Its involvement in the determination of plant height opens up new avenues for the modification of this key trait, which affects multiple agronomic aspects of annual crops, from emergence to harvest index. ; The authors receive strategic funding from the Government of Aragón, research group A08-17R, the Spanish Ministry of Science and Innovation [AGL2016-80967-R], the UK Biosciences and Biotechnology Research Council [BB/P016855/1], the National Sciences Foundation [1127112], and the European Molecular Biology Laboratory. ; Peer reviewed

19 Pags., 6 Tabls., 8 Figs. ; Background and Aims The possibility of using tree materials in early phenological stages, such as dormant buds and flowers, for the prognosis of Fe deficiency occurring later in the year has been studied in peach and pear trees. Methods Thirty-two peach trees and thirty pear trees with different Fe chlorosis degrees were sampled in different commercial orchards. In peach, samples included flower buds, vegetative buds, bud wood, flowers and leaves at 60 and 120 days after full bloom (DAFB). In pear, samples included buds, bud wood, flowers and leaves at 60 and 120 days DAFB. Leaf chlorophyll was assessed (SPAD) at 60 and 120 DAFB. Sampling was repeated for 3–5 years depending on the materials. Mineral nutrients measured were N, P, K, Ca, Mg, Fe, Mn, Zn and Cu. Results The relationships between the nutrient concentrations in the different materials and leaf SPAD were assessed using four different statistical approaches: i) comparison of means depending on the chlorosis level, ii) correlation analysis, iii) principal component analysis, and iv) stepwise multiple regression. In all cases, significant associations between nutrients and SPAD were found. The best-fit multiple regression curves obtained for the multi-year data set provided good prediction in individual years. Conclusions Results found indicate that it is possible to carry out the prognosis of Fe chlorosis using early materials such as buds and flowers. The relationships obtained were different from those obtained in previous studies using a single orchard. The different methods of analysis used provided complementary data. ; Study supported by the Spanish Ministry of Science and Innovation (MICINN; projects AGL2006-1416 and AGL2009-09018, co-financed with FEDER), and the Aragón Government (group A03). HEJ was supported by a FPI-MICINN grant. ; Peer reviewed

17 Pags.- 3 Figs.- 2 Tabls. © 2020 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license. ; Early vigor has been proposed as a favorable trait for cereals grown in drought-prone environments. This research aimed at characterizing early stage shoot and root growth of three Spanish barley landraces compared with three modern cultivars. Genotypes were grown in an automated phenotyping platform, GrowScreen-Rhizo, under well-watered and drought conditions. Seminal and lateral root length, root system width and depth were recorded automatically during the experiment. Drought induced greater growth reduction in shoots (43% dry weight reduction) than in roots (23% dry weight). Genotypic differences were larger under no stress, partly due to a more profuse growth of landraces in this treatment. Accession SBCC146 was the most vigorous for shoot growth, whereas SBCC073 diverted more assimilates to root growth. Among cultivars, Cierzo was the most vigorous one and Scarlett had the least root dry weight of all genotypes, under both conditions. Root growth was redirected to lateral roots when seminal roots could not progress further in dry soil. This study reveals the presence of genetic diversity in dynamics of early growth of barley. The different patterns of growth observed for SBCC073 and SBCC146 should be explored further, to test if they affect field performance of barley in drought-prone environments. ; This research was supported by the Transnational Access capacities of the European Plant Phenotyping Network (EPPN, grant agreement no. 284443) funded by the FP7 Research Infrastructure Programme of the European Union, and by the Spanish Ministry of Science and Competitiveness (MINECO, including FEDER funds) projects AGL2013-487656-R, AGL2016-80967-R and and RFP2012 00015-00-00. RB was supported by a scholarship from CIHEAM, and from a travel grant (Chercheurs en formation a l'étranger) from the Ministry of Higher Education and Scientific Research of Algeria. ; Peer reviewed

42 Pags., 7 Tabls., 3 Figs. and supplementary materials. The definitive version is available at: http://link.springer.com/journal/11295 ; Marker–trait associations based on populations from controlled crosses have been established in peach using markers mapped on the peach consensus map. In this study, we explored the utility of unstructured populations for association mapping to determine useful marker–trait associations in peach/nectarine cultivars. We used 94 peach cultivars representing local Spanish and modern cultivars from international breeding programs that are maintained at the Experimental Station of Aula Dei, Spain. This collection was characterized for pomological traits and was screened with 40 SSR markers that span the peach genome. Population structure analysis using STRUCTURE software identified two subpopulations, the local and modern cultivars, with admixture within both groups. The local Spanish cultivars were somewhat less diverse than modern cultivars. Marker–trait associations were determined in TASSEL with and without modelling coefficient of membership (Q) values as covariates. The results showed significant associations with pomological traits. We chose three markers on LG4 because of their proximity to the endoPG locus (freestone–melting flesh) that strongly affects pomological traits. Two genotypes of BPPCT015 marker showed significant associations with harvest date, flavonoids and sorbitol. Also, two genotypes of CPPCT028 showed associations with harvest date, total phenolics, RAC, and total sugars. Finally, two genotypes of endoPG1 showed associations with flesh firmness and total sugars. The analysis of linkage disequilibrium (LD) revealed a high level of LD up to 20 cM, and decay at farther distances. Therefore, association mapping could be a powerful tool for identifying marker–trait associations and would be useful for marker-assisted selection in peach breeding. ; This study was funded by the Spanish MICINN (Ministry of Science and Innovation) grants AGL-2008-00283 and RFP 2009-00016 and co-funded by FEDER and the Regional Government of Aragón (A44). C. Font was supported by a JAE-Pre fellowship from CSIC (Consejo Superior de Investigaciones Científicas) which enabled her to visit Washington State University, USA, to undertake a preliminary study of association genetics. ; Peer reviewed

8 pages, 4 figures, 3 tables. ; A trial to assess the effects of applying several Fe-containing formulations on Fe-deficient (chlorotic) peach leaves was carried out under field conditions. Solutions consisting of an Fe-containing compound (FeSO4·7H2O, Fe(III)–citrate, Fe(III)–EDTA, Fe(III)–DTPA or Fe(III)–IDHA) and one of five different surfactant treatments (no surfactant, an organo-silicon, an ethoxylated oil, a non-ionic alkyl polyglucoside and a household detergent) were applied to one half of the leaf via dipping, first at the beginning of the trial and then after 4 weeks. The re-greening of treated and untreated leaf areas was estimated with a SPAD apparatus, on a weekly basis, during 8 weeks. At the end of the experimental period, leaves were detached, and tissue Fe, N, P, K, Ca, Mg, Mn, Zn and Cu concentrations were determined in Fe-treated and untreated leaf areas. Treatment with Fe-containing solutions always resulted in leaf chlorophyll (Chl) increases, which however significantly depended on the Fe-source, the surfactant-type and the combination between both formulation components. Untreated leaf zones experienced a Chl increase only in some cases, and this depended on the type of surfactant used. Iron application significantly increased the Fe concentration of treated and untreated leaf areas, especially with some formulations. Foliar treatment with Fe-containing solutions induced significant changes in the concentration of several nutrients as compared to those found in Fe-deficient peach leaves, with changes being similar in treated and untreated leaf areas, although in some elements the extent of the changes was of a different magnitude in both materials. This indicates that some leaf mineral composition changes typical of chlorotic leaves are dependent on leaf Fe concentration rather than on leaf Chl levels. Results obtained are relevant to help understand the factors involved in the penetration and bioavailability of leaf-applied Fe, and to assess the potential of foliar Fe fertilization to control Fe deficiency in fruit trees. ; Study supported by the Spanish Ministry of Science and Education (Projects AGL2004-0194 and AGL2006-01416, co-financed with FEDER), the European Commission (ISAFRUIT project, Thematic Priority 5-Food Quality and Safety of the 6th Framework RTD Programme, Contract no. FP6-FOOD-CT-2006-016279), and the Aragón Government (group A03). V. Fernández was on a CSIC "I3P" post-doctoral contract co-financed by the European Social Fund. ; Peer reviewed

15 p., 6 fig., 4 tab. Copyright © 2014 Loscos, Igartua, Contreras-Moreira, Gracia and Casas. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms. ; Flowering time in plants is a tightly regulated process. In barley (Hordeum vulgare L.), HvFT1, ortholog of FLOWERING LOCUS T, is the main integrator of the photoperiod and vernalization signals leading to the transition from vegetative to reproductive state of the plant. This gene presents sequence polymorphisms affecting flowering time in the first intron and in the promoter. Recently, copy number variation (CNV) has been described for this gene. An allele with more than one copy was linked to higher gene expression, earlier flowering, and an overriding effect of the vernalization mechanism. This study aims at (1) surveying the distribution of HvFT1 polymorphisms across barley germplasm and (2) assessing gene expression and phenotypic effects of HvFT1 alleles. We analyzed HvFT1 CNV in 109 winter, spring, and facultative barley lines. There was more than one copy of the gene (2–5) only in spring or facultative barleys without a functional vernalization VrnH2 allele. CNV was investigated in several regions inside and around HvFT1. Two models of the gene were found: one with the same number of promoters and transcribed regions, and another with one promoter and variable number of transcribed regions. This last model was found in Nordic barleys only. Analysis of HvFT1 expression showed that association between known polymorphisms at the HvFT1 locus and the expression of the gene was highly dependent on the genetic background. Under long day conditions the earliest flowering lines carried a sensitive PpdH1 allele. Among spring cultivars with different number of copies, no clear relation was found between CNV, gene expression and flowering time. This was confirmed in a set of doubled haploid lines of a population segregating for HvFT1 CNV. Earlier flowering in the presence of several copies of HvFT1 was only seen in cultivar Tammi, which carries one promoter, suggesting a relation of gene structure with its regulation. HvCEN also affected to a large extent flowering time. ; This work was funded by the Spanish Ministry of Science and Innovation (MICINN), within the project AGL2010-21929; multiplication of plant materials was funded by project RFP-00015-00-00; all authors were supported by Aragon government project A06. ; Peer reviewed

18 Pags.- 6 Figs.- 3 Tabls. © 2021 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license. ; Roots are important for crop adaptation, particularly in dryland environments. We evaluated root development of 37 durum wheat genotypes (modern cultivars and landraces) in the field at the adult plant stage, through a shovelomics approach. Large genotypic variability was found for root traits. Differences between the landraces and modern cultivars were the main driver of this variation, with landraces showing higher plant vigor for roots and shoots. Nonetheless, genotypic variation within groups was also observed, related to different models of root growth, largely independent of total root length. These two models represented root growth were oriented either to occupy more soil volume, or to occupy less soil volume with increased density. The field results were then compared with root data previously collected in seedlings using a filter paper-based method, to assess whether early root anticipated adult root features. Field plants showed a narrower root angle than seedlings. In particular, landraces presented a narrower root angle than cultivars, but only at seedling stage. Potentially useful correlations were found between the two growth stages for root length and number. ; This research was funded by grants AGL2016-80967-R (Ministry of Science and Innovation of Spain), and the Government of Aragón (group A08_20R). R.B. was funded by a scholarship of the Programme National Exceptionnel (PNE 2018/2019) funded by the Algerian Ministry of Higher Education and Scientific Research. A.C. was funded by FPI contract BES-2017-082746, from the Spanish Ministry of Science and Innovation. The APC was funded by grant PID2019-111621RB-I00 (Ministry of Science and Innovation of Spain). ; Peer reviewed

31 Pags., 4 Tabls., 1 Fig. Available online 15 September 2013. The definitive version is available at: http://link.springer.com/journal/11032 ; Advances in plant breeding through marker-assisted selection (MAS) are only possible when genes or quantitative trait loci (QTLs) can contribute to the improvement of elite germplasm. A population of recombinant inbred lines (RILs) was developed for one of the best crosses of the Spanish National Barley Breeding Program, between two six-row winter barley cultivars Orria and Plaisant. The objective of this study was to identify favourable QTLs for agronomic traits in this population, which may help to optimise breeding strategies for these and other elite materials for the Mediterranean region. A genetic linkage map was developed for 217 RILs, using 382 single nucleotide polymorphism markers, selected from the barley oligonucleotide pool assay BOPA1 and two genes. A subset of 112 RILs was evaluated for several agronomic traits over a period of 2 years at three locations, Lleida and Zaragoza (Spain) and Fiorenzuola d'Arda (Italy), for a total of five field trials. An important segregation distortion occurred during population development in the region surrounding the VrnH1 locus. A QTL for grain yield and length of growth cycle was also found at this locus, apparently linked to a differential response of the VrnH1 alleles to temperature. A total of 33 QTLs was detected, most of them for important breeding targets such as plant height and thousand-grain weight. QTL × environment interactions were prevalent for most of the QTLs detected, although most interactions were of a quantitative nature. Therefore, QTLs suitable for MAS for most traits were identified. ; This work was supported by the Spanish Ministry of Science and Innovation (MICINN), who funded this work with the scholarship BES-2008-009623 (EM), and the projects AGL2010-21929, GEN2006-28560- E and RTA2009-00006-C04. The James Hutton Institute receives grant in aid from the Scottish Government's Rural and Environment Science and Analytical Services Division. ; Peer reviewed

18 Pags.- 7 Figs.- 4 Tabls. © 2021 Puglisi, Delbono, Visioni, Ozkan, Kara, Casas, Igartua, Valè, Piero, Cattivelli, Tondelli and Fricano. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). ; Multi-parent Advanced Generation Inter-crosses (MAGIC) lines have mosaic genomes that are generated shuffling the genetic material of the founder parents following pre-defined crossing schemes. In cereal crops, these experimental populations have been extensively used to investigate the genetic bases of several traits and dissect the genetic bases of epistasis. In plants, genomic prediction models are usually fitted using either diverse panels of mostly unrelated accessions or individuals of biparental families and several empirical analyses have been conducted to evaluate the predictive ability of models fitted to these populations using different traits. In this paper, we constructed, genotyped and evaluated a barley MAGIC population of 352 individuals developed with a diverse set of eight founder parents showing contrasting phenotypes for grain yield. We combined phenotypic and genotypic information of this MAGIC population to fit several genomic prediction models which were cross-validated to conduct empirical analyses aimed at examining the predictive ability of these models varying the sizes of training populations. Moreover, several methods to optimize the composition of the training population were also applied to this MAGIC population and cross-validated to estimate the resulting predictive ability. Finally, extensive phenotypic data generated in field trials organized across an ample range of water regimes and climatic conditions in the Mediterranean were used to fit and cross-validate multi-environment genomic prediction models including G×E interaction, using both genomic best linear unbiased prediction and reproducing kernel Hilbert space along with a non-linear Gaussian Kernel. Overall, our empirical analyses showed that genomic prediction models trained with a limited number of MAGIC lines can be used to predict grain yield with values of predictive ability that vary from 0.25 to 0.60 and that beyond QTL mapping and analysis of epistatic effects, MAGIC population might be used to successfully fit genomic prediction models. We concluded that for grain yield, the single-environment genomic prediction models examined in this study are equivalent in terms of predictive ability while, in general, multi-environment models that explicitly split marker effects in main and environmental-specific effects outperform simpler multi-environment models. ; This research was carried out in the framework of the iBarMed project, which has been funded through the ARIMNet2 initiative and the Italian "Ministry of Agricultural, Food and Forestry Policies" under grant agreement "DM n. 20120." ARIMNet2 has received funding from the EU 7th Framework Programme for research, technological development and demonstration under grant agreement no. 618127. The work was also supported by YSTEMIC_1063 (An integrated approach to the challenge of sustainable food systems: adaptive and mitigatory strategies to address climate change and malnutrition: From cereal diversity to plant breeding), a research project funded by Italian "Ministry of Agricultural, Food and Forestry Policies" in the frame of the Knowledge Hub on Food and Nutrition Security. ; Peer reviewed

Advances in plant breeding through marker-assisted selection (MAS) are only possible when genes or quantitative trait loci (QTLs) can contribute to the improvement of elite germplasm. A population of recombinant inbred lines (RILs) was developed for one of the best crosses of the Spanish National Barley Breeding Program, between two six-row winter barley cultivars Orria and Plaisant. The objective of this study was to identify favourable QTLs for agronomic traits in this population, which may help to optimise breeding strategies for these and other elite materials for the Mediterranean region. A genetic linkage map was developed for 217 RILs, using 382 single nucleotide polymorphism markers, selected from the barley oligonucleotide pool assay BOPA1 and two genes. A subset of 112 RILs was evaluated for several agronomic traits over a period of 2 years at three locations, Lleida and Zaragoza (Spain) and Fiorenzuola d'Arda (Italy), for a total of five field trials. An important segregation distortion occurred during population development in the region surrounding the VrnH1 locus. A QTL for grain yield and length of growth cycle was also found at this locus, apparently linked to a differential response of the VrnH1 alleles to temperature. A total of 33 QTLs was detected, most of them for important breeding targets such as plant height and thousand-grain weight. QTL × environment interactions were prevalent for most of the QTLs detected, although most interactions were of a quantitative nature. Therefore, QTLs suitable for MAS for most traits were identified. ; This work was supported by the Spanish Ministry of Science and Innovation (MICINN), who funded this work with the scholarship BES-2008-009623 (EM), and the projects AGL2010-21929, GEN2006-28560-E and RTA2009-00006-C04. We thank Malcolm Macaulay and Richard Keith fortheir assistance with genotyping software and Marvin analysis respectively. The James Hutton Institute receives grant in aid from the Scottish Government's Rural and Environment Science and Analytical Services Division.

Barley landraces from the western Mediterranean area have not been thoroughly exploited by modern breeding. This study aims at assessing the agronomic value of a core collection of lines derived from landraces of Spanish origin and to compare them with sets of successful old and modern cultivars. The agronomic performance of a set of 175 barley genotypes, comprising 159 landrace-derived lines and 26 cultivars, was evaluated in a series of 10 field trials, carried out over 3 years and several locations. The most relevant trait of the landraces was higher grain yield at low production sites than cultivars, which may be related with better ability to fill the grain under stressful conditions. On the other hand, lateness, excessive plant height and lodging were negative traits frequently found in the landraces. Large genotype-by-environment interaction (GEI) for grain yield was detected, related partly with differences between germplasm groups, probably indicating local adaptation. GEI was also associated with the interaction of heading time and powdery mildew resistance with temperature. ; This research was funded by project RTA01‐088‐C3, granted by the Instituto Nacional de Investigación y Tecnología Agraria y Alimentación (INIA), of the Spanish Ministry of Science and Technology, and co‐funded by the European Regional Development Fund, and by the Aragon regional government, through the funding of research group A06. Samia Yahiaoui was supported by a scholarship from the Agencia Española de Cooperación Internacional (AECI), of the Spanish Ministry of Foreign Affairs.

31 Pags.- 3 Tabls.- 2 Figs.- Additional Supporting Information may be found in the online version of this article (1 Fig., 4 Tabls.). The definitive version is available at: http://onlinelibrary.wiley.com/journal/10.1111/(ISSN)1439-0523 ; Barley landraces from the western Mediterranean area have not been thoroughly exploited by modern breeding. This study aims at assessing the agronomic value of a core collection of lines derived from landraces of Spanish origin and to compare them with sets of successful old and modern cultivars. The agronomic performance of a set of 175 barley genotypes, comprising 159 landrace-derived lines and 26 cultivars, was evaluated in a series of 10 field trials, carried out over 3 years and several locations. The most relevant trait of the landraces was higher grain yield at low production sites than cultivars, which may be related with better ability to fill the grain under stressful conditions. On the other hand, lateness, excessive plant height and lodging were negative traits frequently found in the landraces. Large genotype-by-environment interaction (GEI) for grain yield was detected, related partly with differences between germplasm groups, probably indicating local adaptation. GEI was also associated with the interaction of heading time and powdery mildew resistance with temperature. ; This research was funded by project RTA01-088-C3, granted by the Instituto Nacional de Investigación y Tecnología Agraria y Alimentación (INIA), of the Spanish Ministry of Science and Technology, and co-funded by the European Regional Development Fund, and by the Aragon regional government, through the funding of research group A06. Samia Yahiaoui was supported by a scholarship from the Agencia Española de Cooperación Internacional (AECI), of the Spanish Ministry of Foreign Affairs. ; Peer reviewed

11 Pags.- 3 Figs.- 3 Tabls. © 2021 Crop Science Society of China and Institute of Crop Science, CAAS. Production and hosting by Elsevier B.V. on behalf of KeAi Communications Co., Ltd.This is an open access article under the CC BY-NC-ND license ; Response to vernalization and photoperiod are the main determinants controlling the time to flowering in temperate cereals. While the individual genes that determine a plant's response to these environmental signals are well characterized, the combinatorial effect on flowering time of allelic variants for multiple genes remains unresolved. This study investigated the genetic control of flowering-time in a biparental population of spring barley, derived from a wide cross between a late-flowering European and an early-flowering North-American cultivar. While the major flowering time genes are not segregating in the Beka × Logan cross, large variation in flowering was observed. We identified five QTL, with both parents found to contribute early alleles. The catalog of QTL discovered aligns with several candidate genes affecting flowering time in barley. The combination of particular alleles at HvCEN, HvELF3 and HvFT1 in Logan are responsible for the earliness of this cultivar. Interestingly, earliness for flowering could be further enhanced, with Beka found to contribute three early alleles, including a QTL co-locating with a HvFD-like gene, suggesting that there are diverse aspects of the flowering-time pathway that have been manipulated in these two cultivars. Epistatic interactions between flowering-time QTL or candidate genes were observed in field data and confirmed under controlled conditions. The results of this study link photoperiod-dependent flowering-time genes with earliness per se genes into a single model, thus providing a unique framework that can be used by geneticists and breeders to optimize flowering time in barley. ; This work was supported by the Spanish Ministry of Economy and Competitiveness (grant numbers AGL2010-21929 and AGL2013-48756-R), the Spanish Ministry of Economy and Competitiveness, the Agencia Estatal de Investigación, and the European Regional Development Fund (grant number AGL2016–80967-R), and Government of Aragon (Research Group A08_20R). ; Peer reviewed