Cashew Genetic Resources: A Global Perspective

Being an important commercial crop in the tropical regions of the world, cashew has its origins in the Amazonian region of South America. Out of the 20 species available in the genus Anacardium, cashew is only the commercially cultivated species, though some species have medicinal and ornamental value. Cashew is an evergreen tree that separately bears staminate and perfect flowers. It is predominantly cross-pollinated, and many wild bees have been reported to aid in pollination in addition to honey bees. Botanically, the real fruit of cashew is the nut, and cashew apple is the false fruit. From Brazil, the cashew has been spread to Africa and Asian countries mainly by the Portuguese travelers. Currently, a total of 9800 cashew accessions are conserved in world gene banks, and 35% of them are in Ghana, 9% in India, 8% in Thailand, and 6% in Brazil and Nigeria. In the center of origin, the cashew has two morphotypes – tall and dwarf. However, in other countries, mostly tall ones are predominant. In India, major area under cashew is in coastal areas though it is spreading recently into plain regions with red soil and comparatively high winter temperature. ICAR-Directorate of Cashew Research located in Karnataka state is the nodal center for cashew research in the country and conserves more than 500 accessions of cashew collected all over the world. The germplasm accessions have been conserved, characterized, and evaluated for various characters of interest. Core collections and germplasm database have been developed. Moreover, the accessions have been utilized to develop more than 40 improved genotypes in addition to various studies on biotechnological aspects. As far as Brazil is concerned, more than 600 accessions have been characterized and conserved along with wild species. Dwarf clones with high yield have been released for cultivation. In African and South Asian countries, many studies on utilization aspects of cashew germplasm are under progress. However, most of the countries except Brazil seem to have low to moderate diversity in their accessions. To broaden the genetic diversity, it is essential to introduce diverse material and improved varieties, and hybrids from other countries. A greater cooperation and dialogue are needed among all the countries for exchange of material and information related to various aspects of cashew genetic resources.