Lessons From 20 Years of Studies of Wheat Genotypes in Multiple Environments and Under Contrasting Production Systems

Abstract

Identifying opportunities and limitations for closing yield gaps is essential for setting right the efforts dedicated to improve germplasm and agronomic practices. This study analyses genotypes × environments interaction (G × E), genetic progress, and grain yield stability under contrasting production systems. For this, we analyzed datasets obtained from three Swiss trial-networks of winter wheat that were designed to evaluate genotypes under organic farming conditions, conventional management with low-inputs (150 kg nitrogen (N) ha −1 with no fungicide application) and conventional management with high-inputs (170 kg N ha −1 with fungicide application). The datasets covered the periods from 1998 to 2018 for organic and conventional management with low-inputs and from 2008 to 2018 for conventional management with high-inputs. The trial-networks evaluated each year an average of 36 winter wheat genotypes that included released varieties, advanced breeding lines, and lines for registration and post-registration in Switzerland. We investigated within each trial-network the influence of years, genotypes, environments and their interactions on the total variance in grain yield and grain N concentration using variance components analyses. We further applied mixed models with regression features to dissect genetic components due to breeding efforts from non-genetic components. The genotype as a single factor or as a factor interacting with the environment or the year (G × E, G × year, and G × E × year) explained 13% (organic), 20% (conventional low-inputs), and 24% (conventional high-inputs) of the variance in grain yield, while the corresponding values for grain N concentration were 29%, 25%, and 32%. Grain yield has stagnated since 1990 for conventional systems while the trend under organic management was slightly negative. The dissection of a genetic component from the grain yield trends under conventional management showed that genetic improvements contributed with 0.58 and 0.68 t ha −1 y −1 with low-and high-inputs, respectively. In contrast, a significant genetic source in the grain yield trend under organic management was not detected. Therefore, breeding efforts have been less effective on the wheat productivity for organic farming conditions than for conventional ones.

Wheat nitrogen, phosphorus, potassium, and sulfur uptake dynamics under different management practices

“…The concept of intensification has been used for both crop-specific and cropping systems (Andrade et al, 2017) approach. Similar to our research, other studies have evaluated management intensification strategies in wheat (Herrera et al, 2020;R.P. Lollato, Ruiz Diaz, et al, 2019;Mohamed et al, 1990;Quinn & Steinke, 2019;Roth et al, 2020;B.…”

“…Russell et al, 2020). For example, Herrera et al (2020) evaluated genotypes and environments interaction and grain yield stability under different production systems such as organic F I G U R E 6 Shoot nutrient concentration of (a) N, (b) P, (c) K, and (d) S as affected by biomass during the growing season for standard (SM) and intensive (IM) management systems with (SM + Fung.) or without (IM-Fung.)…”

Agronomic and genetic assessment of organic wheat performance in England: a field-scale cultivar evaluation with a network of farms

“…Furthermore, when this latter work considered breadmaking cultivars only, no significant correlation was found in organic sites between cultivar age and grain yield either, whereas a significant breeding progress was found in non-organic sites. Similar conclusions were reached more recently in Central European environments by Herrera et al (2020) who, in addition, observed that the genetic effect on wheat yield trends over 20 years was significantly positive in 'conventional high-input' and 'conventional low-input' management system, but not significant in 'organic management'. Longer straw in historic cultivars can be associated with increased root proliferation (Bai et al 2013, Barraclough 2010, particularly in terms of seedling root growth (Wojciechowski et al 2009).…”

Wheat grain and straw yield, grain quality, and disease benefits associated with increased management intensity

“…Germplasm selection is an important consideration for farmers, as is the level of management intensity and inputs. A Swiss study examining 20 yr of winter wheat data shows that genetics explains more variation under a high‐input management approach than a low‐input or organic approach (Herrera et al., 2020), suggesting that high‐input management can optimize yields across varieties and enhance knowledge about variety yield potential. In Midwest states like Wisconsin, soft red winter wheat is commonly grown, which has higher yield potential than hard red winter wheat (Lollato, Roozeboom, Lingenfelser, Lemes da Silva, & Sassenrath, 2020), so additional inputs may be worthwhile if they lead to higher yields.…”