RESUMO O objetivo deste estudo foi caracterizar e avaliar populações híbridas e segregantes, provenientes de cruzamentos entre acessos de Cucurbita moschata, com potencial oleaginoso, e cultivares que apresentam o gene para crescimento do tipo moita (Bush), visando à obtenção de genótipos com elevado teor de óleo nas sementes e com crescimento da planta do tipo moita. O delineamento experimental utilizado foi o de blocos casualizados, com três repetições. Cada repetição foi constituída por cinco plantas dos acessos BGH-7319 e BGH-7765, dos cultivares Piramoita e Tronco Verde e dos híbridos F1 (BGH-7319 x Piramoita, BGH-7319 x Tronco Verde, BGH-7765 x Tronco Verde), sendo consideradas as três plantas centrais das parcelas como úteis. Para cada uma das três populações F2 (‘População 1 F2’, ‘População 2 F2’, ‘População 3 F2’), 30 plantas foram avaliadas. Foram utilizados 28 descritores fenotípicos, sendo nove relativos à fase vegetativa das plantas, 12 referentes aos frutos e sete às sementes. Os dados foram submetidos à análise de variância e as médias dos tratamentos contrastadas com as médias das testemunhas, a 5% de probabilidade, pelo teste Dunnett. Na predição do potencial das populações para obtenção de linhagens superiores, foi utilizada a metodologia de Jinks & Pooni (1976). O híbrido BGH-7319 x Tronco Verde destaca-se para os caracteres massa de sementes por fruto, massa de cem sementes, comprimento, largura e espessura da semente, sendo considerada promissora quanto ao teor de óleo nas sementes. A ‘População 2 F2’ derivada do cruzamento entre os genitores BGH-7319 e Tronco Verde foi considerada a mais promissora para planta com crescimento do tipo moita.

ABSTRACT The objective of this study was to characterize and evaluate hybrid and segregating populations of crosses between accessions of Cucurbita moschata, with oil potential, and cultivars that possess the gene of dwarfism (bush), aiming at obtaining genotypes with high seed oil yield and reduced plant architecture. The experimental design was in randomized blocks with three replicates. Each replicate consisted of five plants of the BGH-7319 and BGH-7765 accessions, of the cultivars Piramoita and Tronco Verde and the F1 hybrids (BGH-7319 × Piramoita, BGH-7319 × Tronco Verde, BGH-7765 × Tronco Verde), considering the three central plants of the plots as useful. Thirty plants for each of the three F2 populations ('Population 1 F2', 'Population 2 F2', 'Population 3 F2') were evaluated. Twenty-eight phenological descriptors were applied, nine of which were related to the vegetative phase of the plants, 12 referring to the fruits, and seven to the seeds. The data were subjected to analysis of variance and the means of the treatments were compared with the means of the controls at 5% of probability by Dunnett’s test. In predicting the potential of populations to obtain superior strains, the methodology of Jinks & Pooni (1976) was used. The hybrid BGH-7319 × Tronco Verde stood out for the characteristics of seed mass per fruit, mass of 100 seeds, and seed length, width, and thickness, being promising for the oil content of the seeds. The 'Population 2 F2', derived from the crossbreeding between BGH-7319 and Tronco Verde was to the most promising for plant with shrub-type growth.

ABSTRACT: Artificial neural networks (ANN) are computational models inspired by the neural systems of living beings capable of learning from examples and using them to solve problems such as non-linear prediction, and pattern recognition, in addition to several other applications. In this study, ANN were used to predict the value of the area under the disease progress curve (AUDPC) for the tomato late blight pathosystem. The AUDPC is widely used by epidemiologic studies of polycyclic diseases, especially those regarding quantitative resistance of genotypes. However, a series of six evaluations over time is necessary to obtain the final area value for this pathosystem. This study aimed to investigate the utilization of ANN to construct an AUDPC in the tomato late blight pathosystem, using a reduced number of severity evaluations. For this, four independent experiments were performed giving a total of 1836 plants infected with Phytophthora infestans pathogen. They were assessed every three days, comprised six opportunities and AUDPC calculations were performed by the conventional method. After the ANN were created it was possible to predict the AUDPC with correlations of 0.97 and 0.84 when compared to conventional methods, using 50 % and 67 % of the genotype evaluations, respectively. When using the ANN created in an experiment to predict the AUDPC of the other experiments the average correlation was 0.94, with two evaluations, 0.96, with three evaluations, between the predicted values of the ANN and they were observed in six evaluations. We present in this study a new paradigm for the use of AUDPC information in tomato experiments faced with P. infestans. This new proposed paradigm might be adapted to different pathosystems.

Resumo: O objetivo deste trabalho foi avaliar genitores com potencial de hibridação para o pré-melhoramento do tomateiro (Solanum lycopersicum) quanto à resistência à requeima. Foram utilizados seis acessos de tomateiro (BGH-2102, BGH-2117, BGH-2127, BGH-2130, BGH-2332 e BGH-2343) como genitores resistentes e 15 híbridos F1 originários destes genitores. Utilizou-se o delineamento de blocos ao acaso, com três repetições. As plantas foram inoculadas com uma mistura de esporângios de Phytophthora infestans, agente etiológico da requeima, na concentração de 5x103 esporângios mL-1. A área abaixo da curva de progresso da doença foi utilizada para avaliar a resistência. Realizou-se a análise dialélica, tendo-se considerado o efeito de genótipos como fixo. Estimou-se a capacidade geral e específica de combinação dos acessos. O padrão de resistência dos genitores e da maioria dos F1 foi o mesmo que o das testemunhas resistentes. Foram observados: variabilidade genética aditiva entre os genitores, predominância de efeitos gênicos não aditivos e desvios de dominância bidirecional no controle do caráter. A frequência de alelos favoráveis e divergentes para resistência à requeima é maior nos acessos BGH-2117, BGH-2127 e BGH-2343.

Abstract: The objective of this work was to evaluate parents with hybridization potential for pre-breeding of tomato (Solanum lycopersicum) for resistance to late blight. Six tomato accessions (BGH-2102, BGH-2117, BGH-2127, BGH-2130, BGH-2332, and BGH-2343) were used as resistant parents and 15 F1 hybrids originated from these parents. The design was a randomized complete block with three replicates. The plants were inoculated with a mixture of Phytophthora infestans sporangia, the etiological agent of late blight, at a concentration of 5x103 sporangia mL-1. The area under the disease progress curve was used to evaluate resistance. Diallelic analysis was performed, considering the effect of genotypes as fixed. The general and specific combining ability of the accessions was estimated. The resistance pattern of the parents and of most of the F1 was the same as that of the resistant controls. The following were observed: additive genetic variability among the parents, predominance of nonadditive gene effects, and bidirectional dominance deviations in the control of the trait. The frequency of favorable and divergent alleles for late blight resistance is higher in the BGH-2117, BGH-2127, and BGH-2343 accessions.

O objetivo deste trabalho foi selecionar acessos resistentes à pinta-preta (Alternaria tomatophila) por meio da análise de agrupamento das curvas de progresso da doença em tomateiro (Solanum lycopersicum). Foram avaliados 134 acessos de tomateiro do Banco de Germoplasma de Hortaliças da Universidade Federal de Viçosa (BGH-UFV), no delineamento de blocos ao acaso, além das testemunhas suscetíveis 'Débora' e 'Santa Clara'. As plantas foram inoculadas com uma mistura de conídios de diferentes isolados de Alternaria spp. e avaliadas regularmente quanto à severidade da doença a cada três dias após a inoculação, no total de seis avaliações. Ajustou-se o modelo logístico aos dados de severidade da pinta-preta, e as estimativas obtidas para a incidência final da doença (B1) e a taxa de progresso da doença (B3) foram submetidas à análise de variância multivariada (Manova). As médias dessas estimativas, para cada acesso, foram submetidas à análise de agrupamento. Foram formados 24 grupos distintos com base no agrupamento das curvas de progresso da doença, o que possibilitou identificar os acessos BGH-2143, BGH-2235, BGH-2270 e BGH-2118 de tomateiro como potenciais fontes de resistência à pinta-preta.

The objective of this work was to select accessions resistant to early blight (Alternaria tomatophila) through cluster analysis of the disease progress curves in tomato (Solanum lycopersicum). One hundred and thirty-four tomato accessions from the Banco de Germoplasma de Hortaliças of Universidade Federal de Viçosa (BGH-UFV) were evaluated in a randomized complete block design, as well as the susceptible controls 'Débora' and 'Santa Clara'. The plants were inoculated with a mixture of spores from different Alternaria spp. isolates and evaluated regularly regarding disease severity every three days after inoculation, totalizing six evaluations. The logistic model was adjusted to data on early blight severity, and the estimates obtained for final disease incidence (B1) and rate of disease progression (B3) were subjected to multivariate analysis of variance (Manova). The means of these estimates, for each access, were subjected to cluster analysis. Twenty-four distinct groups were formed based on disease-progress curve clusters, which allowed the identification of the BGH-2143, BGH-2235, BGH-2270, and BGH-2118 accessions as potential sources of resistance to early blight.