Cereal yield trends in northern European conditions: Changes in yield potential and its realisation

In recent decades there has been steady reduction in the rate of increase in cereal yields worldwide. This paper aims to (1) characterise the changes in yield trends of spring (barley, oat and wheat) and winter cereals (rye and wheat) grown in Finland and (2) distinguish between plant breeding achievements and other potential contributors to changes in national yield trends and differences among crops. In this work we used long-term datasets from FAO (FAOSTAT, 2007) (1960–2005) and results from multi-location MTT Official Variety Trials (1970–2005). A mixed model technique was used to divide the yield trends in variety trials into two components: genetic improvements and environmental changes. All trends were characterised using 5 years moving averages. The study period was divided into three agronomically relevant sub-periods: (1) in 1960–1980 agriculture was mechanised and improved basic agricultural practices largely introduced, (2) in 1981–1994 intensified crop management practices were increasingly applied and (3) in 1995–2005 Finland had joined the European Union, which resulted in altered agricultural policies and markets. Plant breeding has successfully increased genetic yield potential of all cereal crops without any indication of reduced rates of improvement. Since 1995 the Finnish national yield trends declined for all crops except wheat, for which the trend levelled-off. The main reasons for this are: cereal production has become less intensive because of (1) application of an environmental programme aimed at increasing the sustainability of agriculture by reducing the environmental load it represents and (2) markedly decreased economic incentives to produce intensively as producer prices for cereals decreased and input prices remained unchanged. National yield trends did not decline because of lack of genetic improvement in yield potential. It is likely that future cereals yield trends will again respond to increasing demand for food, feed, biofuel production and global climate change.