We present a harmonized database of national variety trials and official Value for Cultivation and Use (VCU) trials from the five Nordic countries, Denmark, Norway, Sweden, Iceland, and Finland, focusing on three key crops for that region: spring barley (Hordeum vulgare), red clover (Trifolium pratense), and potato (Solanum tuberosum). Yield is the primary phenotypic trait reported. The location of each trial is also reported, which enables analysis of how weather variability impacts crop performance.

Climate change will have a substantial impact on agriculture, requiring the development of new crop cultivars adapted for resilience to future stresses. Developing a new crop cultivar is a decades-long process, therefore climate change considerations must already be incorporated into breeding programs. National breeding programs have typically involved field trials in a single country, which has functioned satisfactorily during periods of stable climate variability. However, it is widely acknowledged that when field trial information across borders is made available, it can significantly aid plant breeding programs. Here, we present a pan-Nordic multi-environment database that consolidates national trial data and data from VCU trials for spring barley, red clover, and potato. The database harmonizes information on yield across diverse environments, enabling comparative analyses and cross-regional assessments. By providing a unified resource for the Nordic region, this dataset supports the development of more resilient crop varieties and facilitates data-driven breeding strategies under changing climatic conditions.