Combining historical agricultural and climate datasets sheds new light on early 20thcentury barley performance

Barley ( Hordeum vulgare ssp. vulgare ) is cultivated globally across a wide range of environments, both in highly productive agricultural systems and in subsistence agriculture and provides valuable feedstock for the animal feed and malting industries. However, as the climate changes there is an urgent need to identify adapted spring barley varieties that will consistently yield highly under increased environmental stresses. In this research we combined recently released historical weather data with published early 20 th century Irish spring barley trials data for two heritage varieties: Archer and Goldthorpe , following an analysis first published by Student in 1923. Using linear mixed models, we show that interannual variation in observed spring barley yields can be partially explained by recorded weather variability. We find that whilst Archer largely yields more highly, Goldthorpe is more stable under wetter growing conditions, highlighting the importance of considering growing climate in variety selection. Furthermore, this study demonstrates the benefits of access to historical trials and climatic data and the importance of incorporating climate data in modern day breeding programmes to improve climate resilience of future varieties.