In the present paper genetic relationships of twenty varieties of cashew are described on the basis of morphological characters and RAPD (Randomly Amplified Polymorphic DNA) markers. Results obtained for the phenotypic characters based on similarity coefficient were divided into four clusters with 70% similarity. By means of similarity coefficients (S G ), cluster I was found to consist of twelve varieties. Cluster II consisted of a single variety, NRCC-1, cluster III consisted of six varieties and cluster IV had only one variety, Vridhachalam-2. The analysis started by using RAPD markers that allowed us to distinguish 20 varieties. A total of 80 distinct DNA fragments ranging from 0.2 to 3.0 kb were amplified by using 11 selected random 10-mer primers. Genetic similarity analysis was conducted for the presence or absence of bands in the RAPD profile. Cluster analysis clearly showed that 20 varieties of cashew grouped into two major clusters based on similarity indices. The first major cluster comprised one minor cluster. The other major cluster was divided into two sub-minor clusters, one sub-minor cluster having three varieties and the other sub-minor cluster was represented by 15 varieties. Among the 20 varieties, Ullal-3 and Dhana (H-1608) showed the highest similarity indices (87%). It was noted that Vengurla-2 and Vengurla-3 were not grouped into a single cluster but Vengurla-4 has 82% similarity to Vengurla-3. The variety Vengurla-2 has very close similarity (85%) with variety Vridhachalam-3 (M-26/2). The analysis of genetic relationships in cashew using morphological traits and RAPD banding data can be useful for plant improvement, descriptions of new varieties and also for assessment of variety purity in plant certification programmes.

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Genetic diversity among 20 cashew hybrids and their eight parents were assessed using 15 RAPD primers which resulted 1742 alleles with an average of 62.21alleles per genotype. RAPD profiles revealed 94 polymorphic bands out of total 107 scorable bands resulting 87.85% polymorphism. On an average 7.66 bands were produced with a range of 4-15 amplicons per primer. The maximum number (14) of polymorphic bands (210 to 3250bp) was produced by primer OU-34 with high polymorphic information content (PIC) and resolving power (Rp) values. Cashew hybrids H 6 and D 19 maintained very high level of average genetic dissimilarity with rest of the test genotypes. The above hybrids comprising the most divergent genetic group (Cluster-I) had shown significantly above average productivity and these could enrich the cashew gene pool for further genetic improvement for nut quality and yield per se. Besides, the genotype-specific bands identified in the present study are useful for identification of cashew genotypes.

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