William L. Rooney

Department of Soil & Crop Sciences, Texas A&M University, U. S.A.

7.1 Introduction

Sorghum (Sorghum bicolor L. Moench) is an important crop species in the United States and around the world. Because of its substantial heat and drought tolerance, sorghum pro­duction is traditional in semi-arid, subtropical and tropical regions. In addition to abiotic stress tolerance, sorghum is very responsive (in terms of productivity) to more favorable conditions. While primarily known as a cereal grain, sorghum is grown throughout the world as a forage, syrup and more recently, energy crop. In 2008, U. S. farmers harvested about 2.9 million hectares of grain sorghum (USDA NASS, http://www. nass. usda. gov/). Worldwide, the top 20 grain sorghum producing countries harvested 49 472 518 met­ric tonnes of grain in 2007 (FAOSTAT, http://faostat. fao. org/). Unfortunately, production statistics for the other types of sorghum (i. e., forage and sweet) are not reported.

With renewed national and international emphasis on sustainable bioenergy, interest in sorghum as a bioenergy crop has increased for several reasons [1]. Firstly, sorghum has an established production history as a crop in the United States and around the world. This history eliminates the time required for crop domestication, production and market develop­ment and reduces concerns regarding producer acceptance and adoption. Secondly, there is a well established seed industry that is knowledgeable regarding genetic improvement and proficient in seed production. Thirdly, the annual nature of the crop, while a detraction to some, increases the speed and efficiency at which sorghum can be genetically improved and deployed in a production environment. Finally, sorghum has evolved as a standard genetic model for improvement of bioenergy crops. Combined, these factors confirm that sorghum will play an important role in the development and evolution of dedicated energy crops.

Cellulosic Energy Cropping Systems, First Edition. Edited by Douglas L. Karlen. © 2014 John Wiley & Sons, Ltd. Published 2014 by John Wiley & Sons, Ltd.

Within this chapter, a brief summary of sorghum growth and development, composition, relevant production issues and genetic improvement approaches are discussed.