ABSTRACT The bacterial canker, caused by Xanthomonas citri pv. viticola, is the most important bacterial disease of grapevines cultivated in tropical areas. The objectives of this study were to select grape hybrids resistant to bacterial canker based on genotypic values and to evaluate the response of seedless grape hybrids to artificial infection with bacterial canker. Two experiments were conducted. The field experiment (Experiment I) was conducted with 569 hybrids, evaluated for symptoms of bacterial canker, in the absence of an experimental design, using a single individual of each genotype. Experiment II was conducted in a greenhouse, where ten seedless grape hybrids were evaluated in terms of incubation period, incidence, severity, and area under the progress curve of bacterial canker disease incidence, in a completely randomized design. The use of the residual maximum likelihood/best unbiased linear prediction methodology allowed the selection of 40 grape hybrids with lower genotypic values for resistance to bacterial canker. The CPATSA 49.25 and CPATSA 49.86 hybrids showed greater resistance to bacterial canker in all epidemiological parameters evaluated under greenhouse conditions.

Abstract The aim of the present study was to identify grape parent varieties that lead to greater frequency of seedless genotypes in the progenies and to understand the relationships between the seedless trait and other fruit traits. A group of 200 hybrids (F1) originating from 38 crosses among cultivars of Vitis vinifera L. and interspecific hybrids were evaluated in Juazeiro, Bahia, Brazil, over six consecutive crop seasons (2018 to 2021). The progenies were placed in three classes based on seedlessness: completely seedless (class 1), seed traces or soft seeds (class 2), and with seeds (class 3). The mean dry matter of the seeds in each class was 0 mg, 2.3 mg, and 25.7 mg respectively, which corresponded to 40 genotypes (20%) in class 1, 52 genotypes (26%) in class 2, and 108 (54%) in class 3. The interspecific cross ‘BRS Isis’ and ‘Marroo Seedless’ stood out through favoring high frequency of seedless individuals in the progeny (47.5%). The traits associated with berry size (length, diameter, and weight) had high positive correlations with each other. The results obtained make an important contribution for table grape breeding aiming at the development of new table grape cultivars.

Resumo O objetivo do presente trabalho foi identificar genitores que proporcionem maior frequência de genótipos apirenos nas progênies, bem como compreender as relações entre a característica apirenia e outras características do fruto. Foram avaliados 200 híbridos (F1) originados de 38 cruzamentos entre cultivares de Vitis vinífera L., e híbridos interespecíficos, em Juazeiro, Bahia, durante seis safras consecutivas (2018 a 2021). As progênies foram classificadas em três classes quanto à apirenia: completamente sem sementes (classe 1), presença de traço ou semenseparates macias (classe 2) e com sementes (classe 3). A massa fresca média das sementes, em cada classe, foi de 0mg, 2,3mg e 25,7mg, respectivamente, o que correspondeu a 40 genótipos (20%) na classe 1, 52 genótipos (26%) na classe 2 e 108 (54%) na classe 3. O cruzamento interespecífico ‘BRS Isis’ e ‘Marroo Seedless’ destacou-se por favorecer elevada frequência de indivíduos sem sementes na progênie (47,5%). As características associadas ao tamanho de baga (comprimento, diâmetro e massa) apresentaram correlações positivas e elevadas entre si. Os resultados obtidos fornecem subsídios importantes para o planejamento de cruzamentos, avaliação das progênies e seleção de híbridos visando ao desenvolvimento de novas cultivares de uvas de mesa.