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Cashew exhibits genetic variability with respect to size and shape of the tree, colour of the apple (yellow, orange or red), disease resistance and fruit-bearing capacity (Aliyu and Awopetu, 2007). Different haploid numbers have been reported: n = 15 (Machado, 1944), n = 21 (Darlington and Janaki, 1945; Aliyu and Awopetu, 2007), n = 12 (Khosla et al., 1973) and a polymorphic chromosome number 2n = 24, 30, 40 and 42 (Deckers et al., 2001). Flow cytometry studies for ploidy analysis (Olawale, 2012) showed limited accuracy as phenolics interfered with nuclear isolation.

Knowledge of the inheritance of agronomic traits is limited due to several factors, including its outcrossing nature, long juvenile phase, long generation time of homozygous parental lines as well as subsequent filial generations (Cavalcanti and Wilkinson, 2007). In addition, other factors, i.e. low seed set due to disproportionate number of male to hermaphrodite flowers and immature fruit loss, affect controlled pollinations (Bhaskara Rao, 1998). Breeding of cashew is largely dependent on traditional methods of trait selection using phenotypic parameters such as size and weight of the nut. Crop yield is largely dependent on the number of female flowers, length of panicle, fruit set and fruit loss.

Most cashew orchards rely on seedling propagules. As a result, cashew production practices more closely resemble agroforestry than horticulture (Nadagauda et al., 2005). Ultrahigh planting density, drip irrigation and fertigation (Soman et al., 2014), crop management using optimized NPK fertilization, intercropping and organic management of cashew are reported as strategies for enhancing productivity (Jeeva, 2013).