Yanqi Wu

Introduction

Switchgrass (Panicum virgatum L.) is an economically important, warm- season, erect-growing, perennial and widely adapted species in Panicum s. s., which is a taxonomically recognized genus of about 100 specific taxa on the basis of data collected in recent molecular phylogenetic investigations and morphological characteristics (Aliscioni et al. 2003). The North American species is an important component of tallgrass prairies and a common resident in many other habitats on the continent. It is a natural forage species of many herbivorous animals evolved and raised in North America. Since the 1920s, switchgrass has been used to establish plantings for soil conservation, grazing and forage production in mono stands or mixtures with other compatible species (Vogel 2004). For the past two decades, switchgrass has received increasingly more attention in research due to its potential as a bioenergy feedstock crop.

The US Department of Energy sponsored a program, "Herbaceous Crops Research" (HECP) in the late 1980s to perform herbaceous crop screening trials (Wright and Turhollow 2010). The trials of 34 herbaceous species including switchgrass, sorghum and other plants were conducted at multiple sites of different soils and climates in Alabama, Virginia, Indiana,

Department of Plant and Soil Sciences, Oklahoma State University, Stillwater, OK 74078. Email: yanqi. wu@okstate. edu

New York, Ohio, Iowa and North Dakota. Switchgrass along with several other species was recommended for further research as an herbaceous crop, due to its reliable biomass yield across the tested locations, low cultural requirements of water and nitrogen, productivity potential on marginal lands, and favorable characteristics to the environment. In 1991, with a comprehensive and prudent consideration of scientific merits, environmental attributes and DOE funding situations, switchgrass was selected as a sole model herbaceous bioenergy crop (Wright and Turhollow 2010).

Genetic improvement and development of new cultivars through classic breeding, along with sustainable best management practices through agronomic research is the foundation for the development of switchgrass as a dedicated biomass crop (McLaughlin and Kszos 2005). This chapter is attempted to describe and discuss progress in switchgrass improvement using classic genetics and breeding, focusing on target bioenergy traits, basic information of inheritance and cytogenetics, germplasm pools and collections, and breeding and selection methods and the potential to develop hybrid cultivars in switchgrass.