Cindy M. Cox

Increased food and ecosystem security via perennial grains

Perennial grains hold promise, especially for marginal landscapes or with limited resources where annual versions struggle. Despite doubling of yields of major grain crops since the 1950s, more than one in seven people suffer from malnutrition (1). Global population is growing; demand for food, especially meat, is increasing; much land most suitable for annual crops is already in use; and production of nonfood goods (e.g., biofuels) increasingly competes with food production for land (2). The best lands have soils at low or moderate risk of degradation under annual grain production but make up only 12.6% of global land area (16.5 million km2) (3). Supporting more than 50% of world population is another 43.7 million km2 of marginal lands (33.5% of global land area), at high risk of degradation under annual grain production but otherwise capable of producing crops (3). Global food security depends on annual grains—cereals, oilseeds, and legumes—planted on almost 70% of croplands, which combined supply a similar portion of human calories (4, 5). Annual grain production, though, often compromises essential ecosystem services, pushing some beyond sustainable boundaries (5). To ensure food and ecosystem security, farmers need more options to produce grains under different, generally less favorable circumstances than those under which increases in food security were achieved this past century. Development of perennial versions of important grain crops could expand options.

Prospects for Developing Perennial Grain Crops

Abstract Perennial plants, growing in mixtures, make up most of the worlds natural terrestrial biomes. In contrast, monocultures of annual crops are sown on more than two-thirds of global cropland. Grain and oilseed crops are the foundation of the human diet, but to date there are no perennial species that produce adequate grain harvests. Yet perennial plant communities store more carbon, maintain better soil and water quality, and manage nutrients more conservatively than do annual plant communities, and they have greater biomass and resource management capacity. These advantages provide a base from which to begin hybridization and selection for increased resource allocation to developing seeds, a decades-long process that must overcome or circumvent genetic complications. Breeding programs aimed at developing perennial grain crops have been initiated in wheat, sorghum, sunflower, intermediate wheatgrass, and other species.

Progress in breeding perennial grains

Annual cereal, legume and oilseed crops remain staples of the global food supply. Because most annual crops have less extensive, shorter-lived root systems than do perennial species, with a correspondingly lower capacity to manage nutrients and water, annual cropping systems tend to suffer higher levels of soil erosion and generate greater water contamination than do perennial systems. In an effort to reduce soil degradation and water contamination simultaneously - something that neither no-till nor organic cropping alone can accomplish - researchers in the United States, Australia and othercountrieshavebegunbreedingperennialcounterpartsofannualgrainandlegumecrops.Initialcyclesofhybridization, propagation and selection in wheat, wheatgrasses, sorghum, sunflower and Illinois bundleflower have produced perennial progenieswithphenotypesintermediatebetweenwildandcultivatedspecies,alongwithimprovedgrainproduction.Further breeding cycles will be required to develop agronomically adapted perennial crops with high grain yields.

Agriculture: Plant perennials to save Africa's soils

Integrating perennials with food crops could restore soil health and increase staple yields, say Jerry D. Glover, John P. Reganold and Cindy M. Cox.