Extended grain fill stabilizes malt quality across variable environments and nitrogen inputs

Barley (Hordeum vulgare L.) intended for malting must meet strict quality standards to qualify for premium prices. However, producers often struggle to meet these standards in semi-arid climates with increasing climate variability. This uncertainty can also complicate fertility management by causing actual yield potential to differ drastically from pre-season expected yields, leading producers to over- or under-fertilize. This often reduces grain quality, forcing the crop to be sold at lower feed prices. The stay-green trait may improve resilience and grain quality stability in barley by sustaining photosynthesis during grain filling through earlier heading and or delayed senescence. Our objective was to evaluate the impact of three barley cultivars, each differing in combinations of stay-green–associated quantitative trait loci (QTLs), on malt quality stability under four nitrogen (N) treatments across four locations from 2019 to 2023. Across N treatments and location-years, stay-green cultivars exhibited an 8.1% longer grain fill duration, which was associated with an 11.9% reduction in grain protein content and a 4.2% increase in plumpness. Results from this study demonstrate that barley cultivars possessing stay-green traits maintain malt quality under elevated N fertility and environmental stress in semi-arid regions.