Sorghum Breeding

Abstract

Sorghum [Sorghum bicolor (L.) Moench] is the fifth most important cereal crop after wheat, rice, maize, and barley across the world. It is mostly cultivated in the arid and semi-arid tropics for its better adaptation to drought, heat, salinity, and flooding. It is the main staple food for the poorest and most food-insecure people of the world. In sorghum, commercial exploitation of heterosis has been possible owing to availability of a stable and heritable CMS mechanism enabling large-scale, economic hybrid seed production and sufficiently high magnitude of heterosis across a range of production environments for economic characters. The greater contribution of hybrids to yield, compared to improve and landrace varieties, has been demonstrated in almost every situation/condition. The hybrids besides being superior for grain yield and other traits of interest are stable across environments. In India, many improved high yielding hybrids and varieties of kharif, rabi, forage, and sweet sorghum, suitable to different zones/states, have been released for cultivation, which resulted in higher production and productivity. Trait-based approach for the genetic improvement of sorghum has been adopted by use of cutting-edge technologies of plant biotechnology and molecular biology to develop genotypes with improved performance under stress during crop growth and enhanced quality of the produce with extended shelf life of seed, grain, and novel sorghum products. Genomics has made rapid advances during the past decade. The sorghum genome has been sequenced, and important gene transcripts and regulatory mechanisms are being deciphered on a large scale worldwide.The genetic diversity in sorghum provides an opportunity to search for new genes and alleles that are responsible for conferring desirable phenotypes. Genome profiling using molecular markers would provide a large number of DNA markers. Genomic selection programs would pave way for effective utilization of sorghum germplasm for crop improvement. The chapter on sorghum starts with introduction to the crop, history, its origin, evolution, and distribution of species and forms, wild relatives, and plant genetic resources. Information on floral biology, emasculation, and pollination techniques, insight into molecular cytogenetics and breeding, and genetic studies on qualitative and quantitative traits are exhaustively covered for the benefit of users. Breeding objectives including yield, quality characters, biotic and abiotic stresses, exploitation of heterosis, and development of hybrids and varieties through conventional and non-conventional breeding including genomics-assisted breeding are given exclusively for the students and sorghum researchers to serve as reference and use in crop improvement.KeywordsGenetic resourcesGermplasmHybridizationPurity maintenanceVarietal developmentGenomics