Key message Over the last 32 years, a large gain in grain yield (24 %) was achieved in official German variety trials, and despite considerable loss in protein concentration (−7.9 %), winter wheat baking quality was partially improved over the last 32 years. On-farm gain in grain yield (32 %) exceeded gain in trials, but at yield level about 25 dt ha −1 lower. Breeding progress was very successfully transferred into both progress in grain yield and on-farm baking quality. AbstractLong-term gains in grain yield and baking quality of 316 winter wheat varieties from German official trials were evaluated. We dissected progress into a genetic and a non-genetic part to quantify the contribution of genetic improvement. We further investigated the influence of genotype and environment on total variation by estimating variance components. We also estimated genetic and phenotypic correlation between quality traits. For trial data, we found a large gain in grain yield (24%), but a strong decline in protein concentration (−8.0%) and loaf volume (−8.5%) relative to 1983. Improvement of baking quality could be achieved for falling number (5.8%), sedimentation value (7.9%), hardness (13.4%), water absorption (1.2%) and milling yield (2.4%). Grain yield, falling number and protein concentration were highly influenced by environment, whereas for sedimentation value, hardness, water absorption and loaf volume genotypes accounted for more than 60% of total variation. Strong to very strong relations exist among protein concentration, sedimentation value, and loaf volume. On-farm yields were obtained from national statistics, and grain quality data from samples collected by national harvest survey. These on-farm data were compared with trial results. On-farm gain in grain yield was 31.6%, but at a mean level about 25 dt ha−1 lower. Improvement of on-farm quality exceeded trial results considerably. A shift to varieties with improved baking quality can be considered as the main reason for this remarkable improvement of on-farm baking quality.Electronic supplementary materialThe online version of this article (doi:10.1007/s00122-016-2810-3) contains supplementary material, which is available to authorized users.

Key messageYield progress in major German crops is generated mostly due to genetic improvement over the last 30 years. Comparison of trial-station with on-farm yield reveals considerable gaps that are widening over time.AbstractYield progress of newly released varieties for 12 crops from official German trials over the period 1983 until 2012 was analysed to assess their value for cultivation and use (VCU). We paid special attention to dissect progress into a genetic and a non-genetic (agronomic) trend in order to quantify the contribution made by new varieties and by agronomic factors. In this study, we apply mixed models including regression components for genetic and agronomic trends. Ageing effects, depending on the difference of the actual testing year and the first year of testing of a particular variety, were estimated from the difference of fungicide and non-fungicide-treated trial pairs. Significant yield losses were found in all cereal crops due to assumed ageing effects. We compared national on-farm with official VCU trial yields with particular focus on whether gaps are widening over time. Results indicated a significant widening over time. In order to facilitate comparisons of results across crops, we calculated percent rates based on 1983 yield levels obtained from regression estimates. Most of the yield progress was generated by genetic improvement, and was linear showing no levelling-off. Ageing and selection effects need to be taken into account, because they may lead to overestimation of genetic trends. This study showed that contribution of agronomic factors is of minor importance in overall yield progress.Electronic supplementary materialThe online version of this article (doi:10.1007/s00122-014-2402-z) contains supplementary material, which is available to authorized users.

Long-term yield trends have genetic and non-genetic components which may be dissected by a linear mixed model with regression terms. Disease-resistance breakdown must be accounted for in the interpretation. Long-term yield trends of crop varieties may be studied to identify a genetic trend component due to breeding efforts and a non-genetic trend component due to advances in agronomic practices. Many such studies have been undertaken, and most of these inspect trends either by plotting means against years and/or by some kind of regression analysis based on such plots. Dissection of genetic and non-genetic trend components is a key challenge in such analyses. In the present paper, we consider mixed models with regression components for identifying different sources of trend. We pay particular attention to the effect of disease breakdown, which is shown to be confounded with long-term genetic and non-genetic trends, causing an over-estimation of genetic trends based on long-term yield trial data. The models are illustrated using German multi-environment trial data on yield, mildew and Septoria leaf blotch susceptibility for winter wheat and yield, mildew and net blotch susceptibility for spring barley.

Key messageGrain yield of hybrid varieties and population varieties in official German variety trials increased by 23.3 and 18.1%, respectively, over the last 26 years. On-farm gain in grain yield (18.9%) was comparable to that of population varieties in variety trials, yet at a level considerably lower than in variety trials. Rye quality is subject to large year-to-year fluctuation. Increase in grain yield and decline of protein concentration did not negatively influence quality traits.AbstractPerformance progress of grain and quality traits of 78 winter rye varieties tested in official German trials to assess the value for cultivation and use (VCU) were evaluated during 1989 and 2014. We dissected progress into a genetic and a non-genetic component for hybrid and population varieties by applying mixed models, including regression components to model trends. VCU trial results were compared with grain yield and quality data from a national harvest survey (on-farm data). Yield gain for hybrid varieties was 23.3% (18.9 dt ha−1) and for population varieties 18.1% (13.0 dt ha−1) relative to 1989. On-farm yield progress of 18.9% (8.7 dt ha−1) was considerably lagging behind VCU trials, and mean yield levels were substantially lower than in field trials. Most of the yield progress was generated by genetic improvement. For hybrid varieties, ear density was the determining yield component, whereas for population varieties, it was thousand grain mass. Results for VCU trials showed no statistically significant gains or losses in rye quality traits. For on-farm data, we found a positive but non-significant gain in falling number and amylogram viscosity and temperature. Variation of grain and quality traits was strongly influenced by environments, whereas genotypic variation was less than 19% of total variation. Grain yield was strongly negatively associated with protein concentration, yet was weakly to moderately positively associated with quality traits. In general, our results from VCU trials and on-farm data indicated that increasing grain yield and decreasing protein concentration did not negatively affect rye quality traits.Electronic supplementary materialThe online version of this article (doi:10.1007/s00122-017-2865-9) contains supplementary material, which is available to authorized users.

Genotypic, environmental and genotype by environmental variability of 30 different crops was evaluated by estimating variance components from trial series in 16 years. Yield data from official German variety trials for cultivation and use (VCU) were analysed over the period from 1991 to 2006. The natural dominant part was pure environmental variation. Genotype, genotype by environment and plot error are smaller and of the same magnitude. Interaction of genotypes with locations is larger than with years. Compared with variance component estimates of crops from a study involving 16 crops from former West German VCU trials between 1975 and 1986 overall variability of yielding performance was lower in the recent study for all components except for location. Precision of variety comparisons over locations and years is higher in recent VCU trial systems when assuming equal dimensioning of testing resources. Lower values for genotype by environmental variances, especially for the genotype by year component lead to lower standard errors for variety comparisons.Key words: variance components -genotype by environment variability -value for cultivation and use -yield performance Newly bred varieties must be evaluated for their value of cultivation and use (VCU) prior to commercial production. Important traits are yielding performance, quality and disease resistance. More than 900 varieties from about 30 different species enter the trials every year and are tested for 2 or 3 years at up to 25 locations spread over their main growing areas in Germany. The number of varieties entering the first trial year ranges from just a few to over 100, depending on the crop. About 50% of the varieties are withdrawn by the breeder after the first testing year. Another 20-25% leave trials after the second year. Finally only about 25-30% reach the last testing year. For some crops, e.g. cereals, the varieties are grouped to form separate trial series for each testing year, and are grown at 14-25 locations. For other crops, either all varieties are included in one trial series for all testing years, e.g. grasses, or in two series with the first testing year in one series and the second and third together in a separate series. Locations may not be completely identical for each trial series within a period. For some crops only a few locations are the same. This leads to rather unbalanced data sets.The object of testing is to assess the relative genetic potential of the new varieties to release only the best fraction for commercial use at the end of each testing period. However, only the phenotypic performance can be observed in field trials. The genetic value is hidden by variation caused by genotype by environment interaction effects. In this investigation, the phenotypic variation of yielding performance is analysed by considering variance component estimates of individual crops. It is important to know the relative magnitude of the variance components when planning VCU trials. Efficient allocation of trial resources is required to reach a go...