Classical Genetics, Cytogenetics, and Traditional Breeding in Castor Bean

Abstract

Castor being a perennial, cross-pollinated, sexually polymorphic crop with high environ- mental sensitivity, initial plant breeding efforts were restricted to plant height and duration. Domestication of a wild, perennial crop to an annual crop of medium plant height and duration is the first success. Further, develop- ment of a two-line breeding system and standard seed production technology led to successful commercial exploitation of hetero- sis. Being a monotypic genus, diversification of parental base is restricted to intra-generic, intraspecific, or inter-varietal hybridization. Phenotypic expression is highly plastic and varies with locations and seasons. Majority of the morphological characters are monogenic, independently assorted with very limited link- ages among the traits. However, information on genetics of major morphological characters is scattered in several old publications. Con- ventional breeding methods were successful in developing about 40 high-yielding hybrids and varieties with inbuilt resistance to major pests and diseases. An effort is made in the present chapter to consolidate the information on genetics and breeding methods followed in India and elsewhere.