ABSTRACT
Sorghum improvement deals with development of new crop cultivars, which are superior to existing cultivars for traits of interest including high yield, better quality, resistance to pests and diseases and specifi c usability traits (Reddy et al. 2011; Kumar et al. 2013). Availability of genetic variability for these traits, knowledge about their heritability and genetic control, and availability of effective screening methodologies/phenotyping tools are fundamental for success of any crop improvement program. In sorghum, a large collection of germplasm is available at the International Crops Research Institute for the Semi-Arid Tropics (ICRISAT) (~40,000 accessions) and other places with characterization information available for various morphological, agronomic and adaptive traits. Inheritance of major traits is well studied and phenotyping techniques are developed for effi cient selection/screening for major traits of interest. There is continuous exchange of material and information across different research groups. As a result, a large number of sorghum cultivars were developed and commercialized across the world for traits of interest. For example, during the period of 1976 to 2010, a total of 242 sorghum cultivars were released in 44 countries using the ICRISAT-bred sorghum material by private and public sector organizations (Kumar et al. 2011a). The list is quite exhaustive if we consider cultivars developed by other centers in all sorghum growing countries. Focused sorghum improvement programs backed by germplasm sources, information on heritability and gene action for traits of interest, screening techniques, established selection procedures, massive adaptive trials in partners’ locations and above all, collaborative research, contributed for the large scale development and commercialization of improved cultivars in some of the agro-ecosystems. This chapter deals with recent developments with regard to sorghum adaptation to different production systems, major biotic stresses affecting sorghum production, understanding genetic control of biotic stress resistance, screening techniques developed and progress made in cultivar development using this knowledge.
