Capacidade de combinação de linhagens avançadas e cultivares comerciais de melancia

Abstract

Combining ability of advanced lines and marketable cultivars of watermelonThe 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.

COMBINING ABILITY OF FORAGE WATERMELON ( Citrullus lanatus var. citroides ) GERMPLASM

“…Souza, Dias and Queiróz (2013), who analyzed the combination ability of fruit traits for table watermelon, observed the same behavior for FC and PT, which was only NFP divergent with greater SCA than GCA. Table 2.…”

“…According to Souza, Dias and Queiróz (2013), genetic improvement is favored when the additive gene effect predominates because it permits the selection of groups or individuals who are superior and who will develop superior descendants. However, the non-additive gene effect permits promising hybrid combinations because the dominant interaction favors obtaining superior hybrids.…”

Heterose Em Híbridos De Melancia

“…A espessura de casca é uma característica importante para a resistência dos frutos ao manuseio e ao transporte, haja vista que, entre os cultivares utilizados no Brasil, aqueles de frutos com casca mais espessa são mais adequados ao tipo de transporte predominante no mercado interno: frutos a granel transportados em caminhões sem refrigeração, por longas distâncias (Souza et al, 2013). A espessura da casca maior garante maior resistência durante o transporte e maior durabilidade pós-colheita, além de diminuir os danos causados pelo ataque das brocas das cucurbitáceas (Diaphania spp.…”

“…Quando o interesse do melhorista refere-se ao desenvolvimento de híbrido, o estudo da heterose é fundamental para escolha das combinações mais promissoras (Souza et al, 2013), visto que os cultivares híbridos são mais vigorosos e promissores, uniformes e resistentes comparados aos não híbridos (Barros et al, 2010). O híbrido expressa heterose quando é superior à média dos genitores, podendo ser considerada heterose positiva quando uma característica avaliada em um híbrido é maior, ou heterose negativa quando a característica é menor (Borém e Miranda, 2013).…”

Watermelon general and specific combining ability

“…2018 with important genetic diversity sources were reported by AdjoumanI et al (2016), Gama et al (2013) and Gbotto et al (2016). However, to use such genetic resources, a better understanding of genotypes is necessary as regards their main agronomic traits available for the attainment of greater efficiency in the choice of parents and the use of the most adequate breeding techniques (Souza et al 2013).…”