ABSTRACT During experiment planning, determining the number of replicates for tested treatments is important because it directly affects the accuracy of the obtained results. This study was conducted to determine the number of measurements (repetitions) necessary to evaluate the yield traits and soluble solids in Cantaloupe and Gália melon hybrid trials. The study comprised twenty-one experiments, nine for evaluating eight Cantaloupe melon hybrids, and twelve for evaluating nine Galia melon hybrids, conducted in a randomized complete block design with three replicates each. Analysis of variance was performed, and repeatability and genotypic determination coefficients were estimated for each experiment. The use of three repetitions allowed identification of superior genotypes with 83.6 and 80.7% predictions of the real values for the yield and soluble solids, respectively, for Cantaloupe melons. Evaluating the trials with Galia melon using three repetitions allowed prediction of the true value of the genotypes with 86.1 and 98.6% accuracy for fruit yield and soluble solids, respectively. Therefore, the use of three replicates was determined to be sufficient for detecting superior genotypes both for fruit yield and soluble solid content, with more than 80% certainty for their true values.

RESUMO A acidez é um dos principais determinantes do sabor e qualidade dos frutos do meloeiro juntamente com açúcares e compostos voláteis. O objetivo deste trabalho foi estudar a herança do potencial hidrogeniônico (pH) e da acidez titulável dos frutos do meloeiro. Foram avaliadas em um delineamento em blocos casualizados com três repetições as gerações F1, F2 e os retrocruzamentos (RC1 e RC2) a partir dos genitores Védrantais (Cucumis melo subsp. melo var. reticulatus), com alto pH e baixo teor acidez total titulável, e AC-16 (C. melo subsp. melo var acidulus), com baixo pH e elevado teor de acidez titulável. A herança do pH e da acidez titulável em melão são complexas e cada uma envolve um gene maior com efeitos aditivos e de dominância associado a poligenes com efeitos aditivos.

ABSTRACT Acidity is one of the main determinants of the taste and quality of melon fruit, together with sugars and volatile compounds. The aim of this study was to investigate the inheritance of hydrogen potential (pH) and titratable acidity in melon fruit. A randomized block design with three replications was used to evaluate the F1 and F2 generations and backcrosses (RC1 and RC2) of the Védrantais melon (Cucumis melo subsp. melo var. reticulatus) with high pH and low titratable acidity, and of the AC-16 melon (C. melo subsp. melo var acidulus), with low pH and high titratable acidity. Inheritance of pH and titratable acidity in the melon is complex, and each involves a major gene with additive and dominance effects associated with polygenes with additive effects.

Abstract The aim of this study was to evaluate the genotypic performance of twelve Piel de Sapo melon hybrids in the Mossoró-Assú agricultural region, state of Rio Grande do Norte, Brazil, using mixed models. Adaptability and stability of the predicted genotypic values were studied by the Harmonic Mean of the Relative Performance of Genotypic Values (HMRPGV) procedure. The traits evaluated were yield (Mg ha-1) and soluble solids content (ºBrix). The genotype x environment interaction was significant for the two variables in all the hybrid groups evaluated, with predominance of the complex part of the interaction, and this makes the selection process more difficult. Considering the genotypic values predicted, the HMRPGV method allowed identification of hybrids with greater genotypic adaptability and stability. The experimental hybrids HP-09 and HP-06 were more promising for growing in the Mossoró-Assú agricultural region since they have high stability and adaptability, as well as high yield and soluble solids.

RESUMO Muitos fungos habitantes do solo acometem a lavoura meloeira, dentre estes, destaca-se o Myrothecium roridum que prejudica várias partes da planta, inclusive a semente. O presente trabalho estudou o efeito da inoculação de M. roridum sobre a germinação de sementes e crescimento de plântulas de acessos/cultivares de meloeiro, visando identificar genótipos com menor sensibilidade. O experimento foi realizado em delineamento inteiramente casualizados com quatro repetições em fatorial 38 x 2, em que o primeiro fator correspondeu aos acessos/cultivares, com 38 níveis, e o segundo, a inoculação, com dois níveis: com e sem inoculação. Foram avaliadas as características relativas à germinação (porcentagem e velocidade de emergência) e ao crescimento da plântula (altura, diâmetro do colo, peso seco da plântula e índice de área foliar). O fungo M. roridum afetou de forma negativa, a germinação, a velocidade de emergência e o desenvolvimento de plântulas dos acessos de meloeiro. Os acessos com menor sensibilidade ao fungo M. roridum foram A-6, A-8, A-19, A-22, A-39 e A-45.

ABSTRACT A large number of soilborne fungi affect melon crop, among which the species Myrothecium roridum is highlighted for attacking various parts of the plant, including the seed. The present study investigated the effect of Myrothecium roridum inoculation on seed germination and seedling growth of melon accessions/cultivars in order to identify the least sensitive genotypes. The experiment was carried out in completely randomized design with four replicates in 38 x 2 factorial arrangement, in which the first factor corresponded to the accessions/cultivars, with 38 levels, while the second factor, inoculation, had two levels: with and without inoculation. The evaluated traits were related to germination (emergence percentage and rate) and seedling growth (height, collar diameter, seedling dry weight and leaf area index). The fungus M. roridum negatively affected the germination, emergence rate and seedling development of melon accessions. The accessions with least sensitivity to the fungus M. roridum were: A-6, A-8, A-19, A-22, A-39 and A-45.

The aim of this study was to identify sources of resistance toMyrothecium roridumand Podosphaeria xanthii.Initially, 86 inbred lines of the crossing AM-04 x Goldex, 91 inbred lines of the crossing AM-12 x Rochedo, and 75 inbred lines of the crossing ACP x AF-646 were evaluated. The trials were carried out in a greenhouse in a randomized block design with five replications. Seventeen inbred lines were identified as resistant to M. roridum.These inbred lines, as well as the parents and seven differential cultivars (checks) were evaluated for the reaction to P. xanthii.Ten inbred lines were selected as moderately resistant to M. roridumand resistant to P. xanthii.

O presente trabalho teve como objetivo estimar a divergência genética entre linhagens Pele de Sapo e entre linhagens Honey Dew. Foram avaliadas dez linhagens de melão Pele de Sapo e dez linhagens de melão Honey Dew, em experimentos separados, conduzidos em blocos casualizados com três repetições. A divergência genética foi estimada pela distância de Mahalanobis. Foram utilizados os métodos de Tocher e UPGMA para o agrupamento das linhagens. Para as linhagens Pele de Sapo, constatou-se divergência genética com a formação de quatro e cinco grupos conforme os métodos de agrupamento de Tocher e UPGMA, respectivamente. Sugere-se cruzamento das linhagens PS-01, PS-05 e PS-7 entre si ou com as demais linhagens do grupo I. Para as linhagens Honey Dew, verificou-se a formação dos mesmos três grupos nos métodos de agrupamento de Tocher e UPGMA. O grupo II formado pelas linhagens OF-01 e OF-02; o grupo III pela linhagem OF-03 e o primeiro grupo pelas demais linhagens. Com relação às linhagens Honey Dew, recomenda-se os cruzamentos das linhagens OF-01 ou OF-02, com as demais linhagens avaliadas. A linhagem OF-03, com características semelhantes às linhagens OF-01 ou OF-02 pode ser cruzada com as linhagens do grupo I.

The objective of this work was to study the genetic divergence among lines of Pele de Sapo melon and among lines of Honey Dew melon. Ten lines of Pele de Sapo melon and ten lines of Honey Dew melon were evaluated, in separate experiments, both carried in a randomized block design with three replications. The divergence was estimated by the Mahalanobis distance. The methods of Tocher and UPGMA were used for the grouping of the lineages. For the lineages Pele de Sapo, genetic divergence was verified with the formation of four five groups according to the methods of grouping of Tocher and UPGMA, respectively. Must be made crosses among lines PS-01, PS-05 and PS-07 or between theses and other lines of group I. For the lineages of Honey Dew, the formation of the same three groups was verified in the methods of grouping of Tocher and UPGMA. The group II formed by lines OF-01 and OF-02; the group III by line OF-03 and first group by other lines. Considering Honey Dew lines, suggest crosses of lines OF-01 and OF-02 with other lines. The line OF-03 resembling to lines OF-01 and OF-02 must be crossed with the lines of group I.