Speaker
Description
Crop yields are determined by the selected genotypes (G), the applied crop management (M) and the environmental conditions (E) the crop is exposed to, i.e., especially the local soil and seasonal weather conditions. After decades of continuous yield increases in European and German crop production systems, a plateauing of on-farm crop yields is reported in several studies for different regions in recent years. As genotypes, management and weather conditions change simultaneously over time it is difficult to clearly attribute yield changes to one or the other factor including climate change. However, to be able to develop effective climate change adaptation strategies, it is crucial to understand the underlying causes and disentangle the yield effects of changes in G × E × M.
Cereals are highly relevant for agricultural production and food security covering about 50% of European and German cropland. In this study, we hence utilize German-wide yield data to assess trends of on-farm and experimental cereal yields over the last three decade. We assess yield developments of the major cereal crops winter wheat (Triticum aestivum L.), winter triticale (×Triticosecale), winter rye (Secale cereale) hybrid and population varieties as well as spring barley and winter barley (Hordeum vulgare) two-row and six-row varieties. We build on the value for cultivation and use (VCU) trial data, provided by the federal plant variety office. In these trials, each variety is tested for three years for its (additional) VCU at multiple sites throughout Germany before being released to the European market. We further utilize on-farm yield data from the official national census. We apply trend analysis to comparatively assess yield development under experimental vs. on-farm conditions. We further use mixed linear models including regression components for dissecting genetic and non-genetic trends. In this way the contribution of new varieties can be separated from other non-genetic effects, especially changes in management and environment, i.e., climate.
We find that on-farm yields of all major cereals are leveling-off in recent years, with triticale yields showing the most negative trend development and barleys showing the least downturned trend. Comparing these trends to the experimental yields we find a widening yield gap between practical on-farm yields and experimental attainable yields. Dissecting the genetic and non-genetic component of the yield trend, we find no plateau for the genetic yield trend, highlighting the continuous increase in genetic yield potential in cereals. However, we find a strong negative downturn of the non-genetic trend of cereal yield development in the last 10 to 15 years. As crop management in the experimental VCU trials was constant over the past decades, this negative non-genetic trend clearly depicts the strongly negative effect of changes in environmental conditions, i.e., weather conditions, in the last decade.
This study provides novel insights on recent G × E × M developments and their effect on cereal yield trends in Germany. While breeding progress per-sists, climatic conditions acted increasingly negative on cereal yield development in Germany during the last decade.
| Keywords | yield gap assessment; on-farm yields; experimental yields; genetic trend; non-genetic trend |
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