ABSTRACT: Although root rot is one of the major diseases affecting Brazilian cassava (Manihot esculenta Crantz.), little is known about the diversity of root rot pathogens. In this study, diseased plants exhibiting root rot symptoms were collected from cassava-producing regions in five Brazilian states: Bahia, Sergipe, Paraíba, Maranhão, Tocantins, and Paraná. Seventy isolates were obtained and assigned to species complexes based on rDNA's ITS (internal transcribed spacer of the ribosomal DNA) region (ITS1, ITS2 and 5.8S). A total of seven species complexes was found belonging to the genus Fusarium (56/74), followed by Lasiodiplodia (8/74), Neoscytalidium (6/74), and Diaporthe/Phomopsis complex (2/74), Phytophthora, and Corallomycetella (1/74 each). These species were distributed differently according to sample locations and states, but overall, the F. solani species complex (FSSC) was the most prevalent. A number of phylogenetic lineages had not been previously reported as being associated with cassava-root rot disease, such as: F. graminearum (FGSC), F. incarnatum-equiseti (FIESC) and F. chlamydosporum (FCSC) complexes, and a phylogenetic lineage most closely related to P. phaseolorum. Results suggest the need to improve knowledge of the species associated with cassava, including multilocus phylogeny for a more specific characterization, and differences in the resistance background associated with these species, as a strategy to incorporate resistance to multiple pathogens in cassava breeding programs.

RESUMOObjetivou-se avaliar o potencial agronômico de híbridos e linhagens de mamoeiros sintetizados pela Embrapa Mandioca e Fruticultura, visando a identificar e a selecionar genótipos com boas características agronômicas, passíveis de exploração no programa de melhoramento genético e uso direto no sistema de produção de mamão. O trabalho foi conduzido em área do Setor de Campos Experimentais da Embrapa Mandioca e Fruticultura, em Cruz das Almas - BA. Foram avaliados 22 genótipos (oito linhagens, doze híbridos e duas testemunhas: Sunrise Solo e Tainung nº 1) em delineamento de blocos casualizados, com quatro repetições, contendo seis plantaspor parcela, totalizando 528 plantas no ensaio. Para a maioria dos caracteres, observaram-se diferenças significativas a 1% e 5% de probabilidade, exceto para diâmetro do caule (DC). A linhagem L60 e o híbrido H10.60 destacaram-se com as menores médias para a altura da planta (AP) e a altura de inserção dos primeiros frutos (AIPF), e não diferiram estatisticamente entre si. As linhagens L10 e L72, e os híbridos H10.26, H10.60 e H10.72 apresentaram maiores médias de números de frutos comerciais (NFC) que a testemunha Sunrise Solo. Para produtividade (PROD), observou-se ampla variabilidade entre os tratamentos, sendo que 75% dos híbridos e linhagens superaram as testemunhas. Mais de 50% dos genótipos apresentaram médias de sólidos solúveis (SS) superiores a 12°Brix. Com o objetivo de reunir características favoráveis para o desenvolvimento de novas variedades, as linhagens e os híbridos que apresentaram comportamentos satisfatórios para os principais caracteres foram: L60 e H10.60, para AIPF e AP; L10, L72, H10.26, H10.60 e H10.72, para NFC; L10, H10.72, H26.72, H33.56 e H36.45 para PROD; e L26, L36, H10.26, H10.60 e H60.72, para SS.

ABSTRACTThis study aimed to evaluate the agronomic potential of papaya hybrids synthesized by Embrapa Cassava & Fruits, to identify and select genotypes with good agronomic characteristics, exploitable in the breeding program and direct use in the papaya production system. This study was carried out in the Experimental Field Sector of Embrapa Cassava & Fruits, Cruz das Almas - BA. It was evaluated 22 genotypes (eight lines, twelve hybrids and two witnesses: Sunrise Solo and Tainung no 1) in a randomized block design with four replications of six plants perplot, totalizing 528 plants. For most characters significant differences were observed at 1% and 5% probability, except for stem diameter (SD). The line L60 and H10.60 stood out with the lowest averages for plant height (PH) and insertion height of the first fruits (IHFF), and were not statistically different. Lines L10 and L72, and the hybrids H10.26, H10.60 and H10.72 showed higher averages of numbers of commercial fruits (NCF) than the witness Sunrise Solo. For yield, it was observed wide variability among treatments, with 75% of lines and hybrids overcame the witnesses. Over 50% of the genotypes showed soluble solids (SS) averages above 12 ° Brix. Aiming to associate favorable characteristics for development of new varieties, lines and hybrids that showed satisfactory behavior to the main characters were: L60 and H10.60 to IHFF and PH; L10, L72, H10.26, H10.60 and H10.72, for NCF; L10, H10.72, H26.72, H33.56 and H36.45, for productivity (PROD), and L26, L36, H10.26, H10.60 and H60.72, for SS.