Improving the sustainability of malting barley production: Prospects for perennial and annual growth habit varieties

Malted grains—principally barley (Hordeum vulgare L.) —are essential raw materials for brewing. There is an increasing demand for more sustainable crop production practices. At the same time, climate change makes it imperative to identify new production zones, systems, and crops. These demands and imperatives have stimulated interest in converting staple cereal crops, including barley, from annual to perennial growth habit. Most effort has been devoted to wheat (Triticum aestivum L.), and the most progress made in domesticating a perennial relative of wheat. These results prompt the questions: what are the prospects for developing perennial malting barley and is developing perennial malting barley the most direct path to sustainability? Malting barley is a challenge for growth habit conversion due to stringent quality parameters and the extensive infrastructure required for production, processing, and distribution. We discuss four possible paths to achieving the conversion from annual to perennial growth habit while maintaining expected levels of malting quality and agronomic performance: direct domestication, wide hybridization, manipulation of the vernalization and photoperiod sensitivity genes, and mapping annual and perennial forms of ryegrass (Lolium multiflorum L., and L. perenne. L, respectively) as a basis to identify genes conferring perenniality. We conclude that any one of these approaches would require significant, long-term investment. Until such investment is forthcoming, we conclude that there are more cost-effective, short-term solu-tions—notably no-till, multiple cropping, and increased emphasis on fall-seeded barley—that could enhance the sustainability and viability of annual malting barley production.