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Linhares, Brazil

Vivas M.,State University of Norte Fluminense | Silveira S.F.,State University of Norte Fluminense | Cardoso D.L.,Laboratorio Of Melhoramento Genetico Vegetal | Pereira M.G.,Laboratorio Of Melhoramento Genetico Vegetal | And 2 more authors.
Bragantia | Year: 2012

Genetic resistance represents a sustainable alternative to control powdery-mildew in papaya crop. Diallelic crosses were performed among eight papaya genotypes, belonging to 'Solo' and 'Formosa' heterotic groups, four from each one with aiming to indicate possible hybrid combinations that contribute to reducing the severity of powdery-mildew on leaf. The 56 hybrid combinations (F1's and reciprocals) along with their parents were evaluated in a randomized complete block design with four replications. Powdery-mildew severity on leaves was measured in March and May 2010, respectively, at 11 and 13 months after planting. The general and specific combining ability were estimated from the severity data. Thus, considering the estimates of combining ability, the hybrids 'Maradol x Waimanalo', 'Maradol x Sunrise Solo 72/12', 'JS 12-4 x São Mateus', 'Sekati x Waimanalo', 'Sekati x Golden', 'Sekati x Sunrise Solo 72/12', 'Sekati x São Mateus', 'Waimanalo x São Mateus' e 'Golden x São Mateus' are the best combinations for the parents assessed to the severity of powdery-mildew. The results also show the possibility of obtaining hybrids with potential for reducing the severity of powdery-mildew, from crosses between genotypes of the groups 'Solo' and 'Formosa' and at crossings within the 'Solo' group. Source


Ramos H.C.C.,State University of Norte Fluminense | Pereira M.G.,State University of Norte Fluminense | da Silva F.F.,Instituto Federal Of Educacao | Viana A.P.,State University of Norte Fluminense | Ferreguetti G.A.,Caliman Agricola SA
Crop Breeding and Applied Biotechnology | Year: 2011

This study aimed to evaluate the genetic and seasonal influence on sex expression in segregating generations of papaya elite and backcrossed genotypes. In the four seasons of the 2005/2006 growing season, 200 hermaphrodite plants were evaluated. Of the eight studied traits, four were related to flowering and four to fruiting, i.e., to the percentage of normal, deformed, sterile, and total number of flowers, as well as the percentage of total, carpelloid, pentandric, and marketable fruits. Significant differences due to the genotype x season interaction were verified. Based on the genotypic determination coefficient and the variation index it was concluded that winter and spring are most appropriate for the selection of superior genotypes. Thus, selection in early stages of plant development is more successful, indicating that the physiological age may also be a factor involved in the expression of the above traits. Source


Vivas M.,State University of Norte Fluminense | da Silveira S.F.,State University of Norte Fluminense | Gonzaga Pereira M.,Laboratorio Of Melhoramento Genetico Vegetal | Lucia Cardoso D.,Laboratorio Of Melhoramento Genetico Vegetal | Antonio Ferreguetti G.,Caliman Agricola SA
Ciencia Rural | Year: 2013

Genetic resistance represents a viable alternative to control phoma-spot in papaya crop. However, basic studies are necessary to base the choice of genitors and hybrid combinations disease resistant. In this research, a diallel cross was conducted involving eight genotypes of papaya, four of the Solo group and four of Formosa group and it was estimated general and specific abilities of combination for the phoma-spot resistance. The treatments were evaluated in a randomized block design with four replications. The severity of phoma-spot in leaves was quantified in two ocasions: March and May of 2010. The genotypes Maradol JS12-N, Sekati e São Mateus show better general combining ability. The hybrids Maradol x Golden, Maradol x Sunrise Solo 72/12, JS12-N x Golden, JS12-4 x Waimanalo, Sekati x Waimanalo, Waimanalo x Golden, Waimanalo x São Mateus, Golden x Sunrise Solo 72/12 and Golden x São Mateus showed promising results for selection, with negatives values of specific combining ability for severity of phoma spot. Source


Vivas M.,Darcy Ribeiro North Fluminense State University | Silveira S.F.,Darcy Ribeiro North Fluminense State University | Pio-Viana A.,Laboratory of Plant Breeding | Amaral-Junior A.T.,Laboratory of Plant Breeding | And 2 more authors.
Crop Protection | Year: 2015

The absence of cultivars with satisfactory levels of genetic resistance justifies the search for genotypes incorporating disease-resistance genes in the papaya-breeding program. In this study, two field-plot experiments were carried out in the municipality of Linhares, Espirito Santo State, Brazil, to evaluate resistance to foliar diseases in a papaya germplasm collection. The variables incidence and severity of leaf diseases and black spot incidence and severity on fruits were considered for uni- and multivariate variance analyses. The Mahalanobis distance was calculated for each pair of genotypes, and the distance matrix was used for clustering methods. Papaya genotypes were grouped by the Tocher method and the hierarchical method of Un-weighted Pair Group with Arithmetic Mean (UPGMA) was used for dendrogram construction. Although no immune reaction was observed among the genotypes for any of the leaf diseases, the data analyses highlight the following genotypes as potential sources of resistance genes for use in a papaya breeding program: 'STZ 23 PL', 'Maradol', 'Maradol GL', 'JS 11', 'Americano', 'Caliman SG', 'Sekati', 'Sekati FLM', 'Waimanalo', 'Caliman AM', 'Papaya 46', 'Tailândia' and 'SH 12-06'. This is the first time multivariate analyses were employed to evaluate multiple disease resistance in a papaya crop. © 2015 Elsevier Ltd. Source


Vivas M.,State University of Norte Fluminense | da Silveira S.F.,State University of Norte Fluminense | Cardoso D.L.,State University of Norte Fluminense | Pereira M.G.,State University of Norte Fluminense | And 2 more authors.
Tropical Plant Pathology | Year: 2012

Diallelic crosses were performed between eight papaya genotypes belonging to the 'Solo' and 'Formosa' heterotic groups (four belonging to each group). The 56 hybrid combinations (F1's and reciprocals) along with their parents were evaluated in a complete randomized block design for resistance to black spot disease, caused by Asperisporium caricae. The severity of black spot in leaves and fruits was quantifed in two occasions, March and May 2010. When the genotype effect was signifcant, heterosis as well as general and specifc combining ability were estimated from the severity data. The genotypes 'JS12-N', 'Sekati', 'Golden' and 'Sunrise Solo 72/12' displayed better general combining ability for both characteristics. Twelve hybrids displayed promising results for selection, with low values of specifc combining ability for resistance to black spot leaves and fruits. The heterotic group did not affect hybrid performance or heterosis estimates. Heterosis in papaya for resistance to black spot may provide signifcant genetic gains from both inter-and intra-heterotic crosses, and especially from hybridizations involving genotypes of the 'Solo' group. © Brazilian Phytopathological Society. Source

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