Stability, across environments, of grain and alcohol yield, in soft wheat varieties grown for grain distilling or bioethanol production

Background: Soft-milling wheat has potential use for both grain whisky distilling and bioethanol production. Varietal comparisons over wide-ranging environments would permit assessment of both grain and alcohol yield potential and also permit the stability across environments, for these parameters, to be compared.

Results: For 12 varieties, analysis of variance showed highly significant effects of variety, site, season and fertiliser application on grain and alcohol yield. There were also significant interactions between these factors and, consequently, varieties varied in stability across environments as well as in mean values for the parameters assessed. Alcohol production per hectare was affected more strongly by variation in grain yield than alcohol yield, but increasing grain protein content reduced alcohol yield and, therefore, utility for grain distilling.

Conclusion: To maximise energy production, the best varieties for bioethanol would combine high and stable grain yield with slower reduction of alcohol yield as grain protein increases. For grain distilling, where the energy balance is less important, high alcohol yield will remain the key factor. Data derived using near infrared spectroscopy can be valuable in assessing stability of quality traits across environments.