Papaya (Carica papaya L.) is one of the main tropical fruits consumed in Brazil. The country is also one of the main papaya exporters, but one of the factors hindering its production lies on foliar diseases such as papaya black spot, which is caused by fungus Asperisporium caricae. This pathogen is widely distributed in the main producing regions of the Brazilian coastal area. Phylogeographic studies contribute to the knowledge about the genetic diversity and geographical distribution of genealogical lineages (haplotypes) and help better understanding the reproductive and evolutionary processes of closely related species or of a single species. Such information is useful in studies about phytopathogenic fungi because it enables identifying the most prevalent genealogical lineages in a given location, as well as inferring dispersal routes and providing information on the origin and frequency of exotic material introduction events. Results in this type of study can significantly help developing new disease control strategies. Literature still lacks studies on the Papaya x A. caricae pathosystem. Based on the phylogenetic and phylogeographic analysis applied to nucleotide sequences of the Internal transcribed spacer (ITS) gene, we herein address the genealogical and dispersal events recorded for this pathogen in order to better understand its evolution in, and adaptation to, Brazilian orchards. Three haplotypes were identified among the A. caricae isolates; their distribution was mostly related to the geographic distance between sample collection regions rather than to any reproductive or evolutionary processes presented by the species. The low variability among the herein studied isolates may result from the physiological specialization (survival exclusively associated with the host plant) and from the regional transport of contaminated fruits (with lesions and spores), besides the low contribution of reproductive events, which corroborate the lack of knowledge about the sexual stages of A. caricae.

This study described the main characteristics of the maize cultivars UENF MSV2210 and UENF MS2208. Adapted to the North and Northwestern regions of the state of Rio de Janeiro, they have a high agronomic performance and were developed for both silage and green maize production.

The aim of this study was to estimate the correlation coefficients and slicing the phenotypic correlations into direct and indirect effects by path analysis between morphoagronomic and bromatological traits in corn hybrids for silage. Nineteen topcross hybrids and five controls were assessed in a randomized block design with four replications in two environments (Campos dos Goytacazes and Itaocara, RJ), in the 2013/2014 agricultural year. Phenotypic correlations and path analysis were estimated between morphoagronomic (average plant height; average first ear height; average stem diameter; ear yield with husk at silage point; grain yield at silage point; green mass yield) and bromatological (dry matter; crude protein; neutral detergent fiber; lignin; crude fat and mineral matter) traits. The highest correlation estimates were obtained between dry matter and crude protein and between dry matter and neutral detergent fiber, with magnitudes of 0.97 and 0.98, respectively. The coefficient of determination was high, indicating that the assessed components explain much of the variation in the dry matter content. Path analysis showed that traits with highest direct effect on dry matter content were the yield of green mass, crude protein, neutral detergent fiber, crude fat, and mineral matter associated to high correlations of 0.96, 0.97, 0.98, 0.90, and 0.96, respectively. The results showed the possibility of obtaining significant gains through indirect selection

No abstract

The occurrence of the genotype × environment (G × E) interaction is one of the main factors that hinder the selection of adapted and stable genotypes. The genotype and G × E interaction (GGE) biplot methodology is an efficient process to detect corn (Zea mays L.) hybrids for silage and, consequently, will help in the recommendation of new and more stable hybrids in different environments in breeding programs. In this sense, this study aimed to evaluate and select corn hybrids for silage that simultaneously combine high yield and stability in different environments in the state of Rio de Janeiro, Brazil, via GGE biplot. Eleven corn hybrids, eight precommercial topcrosses and three commercial controls, were evaluated at three sites (Campos dos Goytacazes, Cambuci, and Itaocara, Rio de Janeiro) during two seasons: the 2017-2018 season and 2018-2018 off-season. The experiments were designed in completely randomized blocks with three replications. Individual and joint analyses of variance were performed and, after detecting significant interaction between genotype and environment, the adaptability and phenotypic stability of corn genotypes for silage were analyzed using the GGE biplot methodology. The GGE biplot analysis was efficient in interpreting the data and represented 83.68% of the total variation in the first two principal components. The use of the GGE biplot method allowed the recommendation of more productive, stable, and responsive hybrids for the state of Rio de Janeiro. The hybrid UENF MS2208 is indicated for cultivation in the state of Rio de Janeiro for combining high green biomass yield and stability. INTRODUCTIONCorn (Zea mays L.) is a crop that has importance in the socioeconomic, environmental, and cultural spheres worldwide and also in Brazil. It mainly is due to its potential use in human and animal food and biofuel production among others AEC, average environment coordinate; G × E, genotype × environment interaction; GGE, genotype and genotype × environment interaction; GMY, green biomass yield.