A abóbora é amplamente cultivada e consumida no Brasil, em especial na região Nordeste. O espaçamento entre e dentro da linha são cruciais para o desenvolvimento e produção da cultura. Com o objetivo de avaliar diferentes espaçamentos de plantio na produtividade de acessos e cultivar de abóbora, instalou-se um experimento no período de maio a setembro de 2010, no campo experimental da Embrapa Semiárido em Petrolina-PE. O delineamento experimental utilizado foi de blocos ao acaso, em esquema fatorial 5x3, compreendendo quatro acessos selecionados do Banco Ativo de Germoplasma de Abóbora (Acessos: A422, A612, A620 e A627) e a cultivar Jacarezinho como testemunha, e três espaçamentos entre plantas (4x1; 4x2 e 4x3 m), com quatro repetições. Maior produtividade foi obtida pelo acesso A612 (17,3 t ha-1), seguido pelo acesso A422 (15,2 t ha-1) e, o pior desempenho foi obtido pela cultivar Jacarezinho (12,2 t ha-1), sem diferenciar dos demais acessos. Para espaçamento entre plantas observou-se que as maiores produtividades foram verificadas no menor espaçamento (4x1 m) com 18,2 t ha-1, e menores produtividades no espaçamento de 4x3 m (11,9 t ha-1). O acesso A612 sobressaiu-se com maior massa fresca (3,5 kg fruto-1), não se diferenciando estatisticamente do acesso A422, que alcançou 3,2 kg fruto-1. A cultivar Jacarezinho e o acesso A620, com respectivos 1,9 e 2,0 kg fruto-1 obtiveram os menores valores para massa fresca do fruto, assim como maior número de frutos por planta com 4,7 e 4,6 frutos plantas-1, respectivamente.

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The aim of this study was to estimate the phenotypic divergence among fourteen pumpkins accessions of the cucurbits Germplasm Active Bank of Embrapa Semiárido, in order to support breeding program to these species. Nine morphoagronomic descriptors were analyzed by the principal components and by UPGMA techniques. In the analysis of principal components, the formation of three contrasting clusters was observed, each one composed of two accessions. There occurred also the formation of one core group composed of five accessions, being the accessions called 683 and 684 collected in Bahia and the other in Maranhão. The most divergent accessions were 620, 624 and 748. The variables of the greatest contribution to the genetic divergence were diameter, weight and average length of the fruit. In the UPGMA analysis, obtained from the symmetric matrices generated by the Mahalanobis distance for the nine descriptors, there was the formation of one core group, composed of ten accessions, whose similarity was 45.71%, with geographically divergent accessions presenting the greatest similarity. Three accessions were not clustered with others. The study identified phenotypic variability for the analyzed characters and the absence of relationship between place of collection and phenotypic diversity.

The estimation of genetic parameters allows for the selection of superior individuals for important traits in plant breeding. The objectives of the present study were to estimate and predict the gains in genetic parameters, as well as to select superior individuals for morphoagronomic and pulp quality characteristics in C. moschata. Ten progenies derived from accessions collected in the northeast of Brazil were evaluated for 17 morphoagronomic characteristics and chemical quality of the pulp, including total carotenoids and β-carotene. The low values of additive genetic variance denote the need for additional selection cycles for the evaluated characteristics. Heritability greater than 30% was observed for 13 of the 17 variables analysed, indicating success in selection. Likewise, accuracy values between 74 and 93% were obtained for 15 of the evaluated variables, demonstrating the existence of high genetic variance. Individual ranking was conducted for the variables fruit weight (FRW), soluble solid content (SSC), titratable acidity (TA), total carotenoid content (TCC) and β-carotene (β-Car), identifying five individuals of progeny 10 that were promising for advancement in selection for SSC, TCC and β-car. In ranking the simultaneous evaluations for all the characteristics and taking into account the formats piriform and 'moranga', two individuals of progeny 10, which coincided with the top ranking for SSC, CBT and β-car, were identified. This identification of more than one promising individual enhances the potential of the progenies evaluated for the development of commercial and productive lines in semi-arid conditions.

This study had the following objectives: to investigate the sexual expression in seven watermelon populations; to evaluate some population parameters and the genetic potential of a population (PCS) obtained by crossing and segregating for sexual expression and other traits. For verifying the sexual expression, populations were evaluated with respect to type of flower, under controlled conditions. Maternal and selfed progenies were obtained from the PCS population for field evaluation, considering: fruit yield per plant, fruit weight, number of fruits per plant, flesh colour and sugar content. On the basis of molecular marker data (RAPD), the outcrossing rate (t m and t s ), allelic frequencies (p i ) and the coefficient of inbreeding (F) were estimated for the PCS population. Results indicated that populations B9 and P14 are andromonoecious in which natural selfing occurs, giving rise to normal fruits. The remaining populations are monoecious. Population PCS practices a mixed mating system (t m = 0.765) and, having shown sufficient genetic variation and relatively low inbreeding depression, has high potential for breeding purposes. The importance of obtaining accurate estimates of the outcrossing rate is pointed out, specially because sexual expression and the mating system are genetically conditioned in watermelon populations.