Perennialism and Weediness in the Saccharinae
The apparent contrast in demands for sustainability and productivity in modern agriculture may be reconcilable via the genetic difference in degree between perennialism and weediness. Effective use of genomic tools may soon allow precise metering of the g
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Perennialism and Weediness in the Saccharinae Russell W. Jessup
Abstract The apparent contrast in demands for sustainability and productivity in modern agriculture may be reconcilable via the genetic difference in degree between perennialism and weediness. Effective use of genomic tools may soon allow precise metering of the genetic components required to ensure perennial life status, minimize weediness, and maximize crop yields. The Saccharinae includes both model genomic species and leading food, feed, forage, fuel, and industrial crops upon which translational technologies can be evaluated and deployed. In particular, a balance between the high agricultural productivity demanded in order to minimize land requirements and perennial growth habits necessary to ensure sustainable cropping systems is sought. Keywords Perennialism • Weediness • Sorghum halepense • Saccharum spontaneum • Miscanthus • Microstegium • Rhizomes • Tillering • Polyploid
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Introduction
The world’s terrestrial biomes consist primarily of perennial plants in polyculture (Chiras and Reganold 2004), yet more than two-thirds of global croplands contain monocultures of annual crops. Such annual crops require intensive management, well-timed inputs, favorable weather during narrow time windows, and have shorter growing seasons and less-extensive root systems that provide diminished protection against soil erosion, water and nutrient leaching, subterranean carbon losses, and biotic/abiotic pressures (Glover 2005). Perennial plants are in contrast efficient soil,
R.W. Jessup (*) Department of Soil & Crop Sciences, Texas A&M University, 370 Olsen Blvd., 2474 TAMU, College Station, TX 77843-2474, USA e-mail: [email protected] A.H. Paterson (ed.), Genomics of the Saccharinae, Plant Genetics and Genomics: Crops and Models 11, DOI 10.1007/978-1-4419-5947-8_21, © Springer Science+Business Media New York 2013
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nutrient, and water managers consisting of substantial subterranean structures that have significant yet unutilized potential for repartitioning into aboveground grain and biomass. The North American flora consists of approximately 5,000 nonnative and 17,000 native higher plants (Morin 1995; Morse et al. 1995). Despite this influx of 23% alien species in four centuries of contact with other parts of the world, only between 67 and 104 plant taxa are responsible for 90% of the economic damage caused by weeds (Holm et al. 1997). Invasive species number approximately 550 worldwide and represent an even smaller component of the world’s estimated 250,000 species of flowering plants (Weber 2003). Williamson and Fitter (1996) proposed the “Tens Rule,” stating that on average one in ten introduced species will escape cultivation, one in ten of these will become naturalized as self-sustaining populations, and one in ten of these will become invasive. Weeds generally have a high level of phenotypic plasticity, perhaps derived from heterozygosity via polyploidy, that provides valuable adaptive flexibility. Although detailed studies are
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