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Not AvailableCastor being a perennial, cross-pollinated, sexually polymorphic crop with high environmental 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, development of a two-line breeding system and standard seed production technology led to successful commercial exploitation of heterosis. 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 linkages among the traits. However, information on genetics of major morphological characters is scattered in several old publications. Conventional 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.Not Availabl

Past, present and future of organic nutrients

Slowing crop yield increases despite high fertiliser application rates, declining soil health and off-site pollution are testimony that many bioproduction systems require innovative nutrient supply strategies. One avenue is a greater contribution of organic compounds as nutrient sources for crops. That plants take up and metabolise organic molecules ('organic nutrients') has been discovered prior to more recent interest with scientific roots reaching far into the 19th century. Research on organic nutrients continued in the early decades of the 20th century, but after two world wars and yield increases achieved with mineral and synthetic fertilisers, a smooth continuation of the research was not to be expected, and we find major gaps in the transmission of methods and knowledge