The combining ability analysis is an important tool to estimate parameters used for superior genotype selection in breeding programs. Besides aiding in the choice of the best parents and promising hybrids, this technique enables the characterization of the nature and magnitude of gene expression related to agronomic traits of interest. This study aimed to estimate the effects of general combining ability (GCA) and specific combining ability (SCA) in a partial diallel cross of watermelon genotypes. The assay was carried out at the Experimental Station of Embrapa Rondônia, in Machadinho do Oeste, Rondônia state, Brazil. The parents were organized in two groups, the first being composed by three advanced lines: Cpafro 34.305, Cpafro 74.105 and Cpafro 45.202; and the second, by three cultivars: 'Charleston Gray', 'Sugar Baby' and 'Omaru Yamato'. Parents and hybrids were evaluated with regard to 11 agronomic traits. The study followed a randomized blocks design, with three replications, and seven plants per plot, spaced by 3.0 m between rows and 1.0 m between plants. The effects of GCA were superior than those of SCA to most traits, evidencing the predominance of the additive interaction on the control of those characters. Favorable GCA effects were verified on many parents, 'Sugar Baby' and 'Charleston Gray' being the most promising to intra-population breeding strategies aiming to develop smaller and larger fruit varieties, respectively. On the basis of the SCA effects, Cpafro 74.105 x Charleston Gray (large fruits) and Cpafro 74.105 x Sugar Baby (small fruits) were the best combinations, presenting more potential to commercial cultivation.
Citrullus lanatus; genetic breeding; diallel analysis; additive effects
