Rainfall and temperature impacts on barley (Hordeum vulgare L.) yield and malting quality in Scotland

Barley is one of the most important cereals worldwide and is a key crop for Scotland's agriculture due to its use in distilleries to produce whisky. Climatic variability, especially significant changes in rainfall patterns are a present challenge for barley production. Thus, the objectives of this study were: i) to evaluate the performance of a crop model to simulate water and N stresses in spring barley in the east of Scotland; ii) to quantify the impacts of rainfall and temperature on barley grain yield and quality; and iii) to understand how grain nitrogen concentration varies in relation to climate variability. Three field experiments were undertaken at the James Hutton Institute near Dundee, UK. The 2018 experiment consisted of two levels of N (0 N and 120 N) and two levels of water (rainfed and irrigated). Data from two experiments were used as additional evaluation. The Decision Support System for Agrotechnology Transfer (DSSAT v4.7) model was used to evaluate the crop performance. The evaluation of the crop model using the different years, locations and water by nitrogen stress levels, using the same cultivar (Concerto), showed that the cultivar parameters were well calibrated. There was a weak negative and non-significant (p = 0.14) relationship between air temperature and simulated yield, but a strong (p < 0.05) positive relationship between growing season rainfall and simulated yield. During the spring barley growing season (Apr-Aug), the last two decades were drier than the long-term average, with May (time of expansive growth) having about 25 mm less rainfall than the long-term average. The results of this study highlight how rainfall is more important than the temperature for the production of spring barley in Scotland. Our simulated results showed that the premium grain for distilling is reached 41 out of 45 years investigated in this study.