|VAN TASSEL, D.|
|Holland, Jim - Jim|
Submitted to: Critical Reviews in Plant Sciences
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/15/2001
Publication Date: 2/1/2002
Interpretive Summary: Grain production is necessary for human survival, yet current methods of grain production are associated with unsustainable rates of topsoil erosion. A new approach to maintaining grain production while minimizing topsoil erosion is the development of perennial grain crops. Preliminary experiments in wheat and a few other crops indicate that perennial grain crops with adequate yield levels could be developed, if a larger, more concerted effort were made. This paper reviews the potential and the difficulties of perennial grain crop development, and indicates the most likely routes for the creation of perennial forms of modern grain crops.
Technical Abstract: One-third of the planet's arable land has been lost to soil erosion in recent decades, and the pace of this degradation will increase as the limits of our food-production capacity are stretched. The persistent problem of worldwide soil erosion has rekindled interest in perennial grain crops. All of our current grain crops are annuals; therefore, plant breeders must develop an array of new perennial grains - grasses, legumes and others - before erosion-free methods of producing food can be tested. Fortunately, many perennial species can be hybridized with related annual crops, allowing us to incorporate genes of domestication much more quickly than did our ancestors who first selected the genes. Some grain crops - rye, rice, and sorghum - can be hybridized with close perennial relatives to establish new gene pools. Others - wheat, oat, maize, soybean, and sunflower - must be hybridized with more distantly related perennial species and genera. Some perennial species with relatively high grain yields - intermediate wheatgrass, wildrye, lymegrass, eastern gamagrass, Indian ricegrass, Illinois bundleflower, Maximilian sunflower, and probably others - are candidates for direct domestication without interspecific hybridization. To ensure diversity in the field and foster further genetic improvement, breeders will need to develop deep gene pools for each crop. Discussions of breeding strategies for perennial grains have concentrated on allocation of photosynthetic resources between seeds and vegetative structures. But perennials will likely be grown in a more diverse agro-ecosystems and require arrays of traits very different from those usually addressed by breeders of annuals.