ABSTRACT
Cassava serves as primary staple food of millions of people in the tropics and subtropics, and is used as a carbohydrate source in animal feed. Knowledge of agro-morphological characteristics and genetic relatedness is essential for an efficient recombination of varieties in a breeding program. The objective of the present study was to determine genetic relatedness and morpho-agronomic differentiation among Congolese cassava collection for breeding purposes. The morphological and agronomic characters were highly variable among accessions. Every accession could be differentiated from any other one. There were significant genotypes x location interactions for storage root yields. Root weights were positively correlated with the number of roots per plant. In general, all the improved varieties were tolerant or resistant to the Cassava Mosaic Virus (CMV) while the local (non-improved) varieties were susceptible. But the reaction to Cassava Bacterial Blight (CBB) confirmed that genetically improved accessions are susceptible and local varieties are resistant. Molecular analysis revealed that the accessions analyzed were genetically distant with 80% of genetic distance values estimated above 0.5. One local accession was an out-group that was separated from the main groupings with 100% degree of confidence. More importantly, there were no associations between genetic relationships and morphological similarities based on lobe shape, leaf colour, petiole colour, petiole orientation, and stem colour. Although the Congolese cassava genepool is small, there is enough variability to sustain a breeding program without new introductions of germplasms.
ABSTRACT
O objetivo do presente trabalho foi caracterizar os aspectos morfológicos e agronômicos de três acessos de jambu (Spilanthes oleracea L.) nas condições do Norte de Minas Gerais. O estudo foi desenvolvido em casa de vegetação, no período de abril a junho de 2009, no Instituto de Ciências Agrárias da Universidade Federal de Minas Gerais (ICA/UFMG), localizado na cidade de Montes Claros, Minas Gerais, Brasil. O delineamento experimental foi o inteiramente casualizado, com três tratamentos e oito repetições. Os tratamentos foram os acessos de jambu (1- Montes Claros/MG; 2- Pará, Norte do Brasil; 3- Cristália/MG). Dois meses após o transplantio, foram avaliados o comprimento da inflorescência (cm), o comprimento e a largura das folhas do terceiro nó de cada planta (cm) e a matéria fresca e seca da parte aérea e das inflorescências (g). Foram também caracterizadas a coloração dos caules e os tipos de inflorescências. A cor dos caules foi distinguida visualmente, variando de roxo intenso, acessos de Cristália e Montes Claros, a verde claro, acesso do estado do Pará. Os subtipos de inflorescência foram caracterizadas como simples ou geminadas e alongadas ou globóides. Observou-se que o acesso de Jambu, proveniente do estado do Pará, apresentou os melhores resultados para a maioria das características avaliadas. Esse acesso apresentou inflorescências dos tipos simples alongada,e, ocasionalmente, geminadas, tanto globóides como alongadas, enquanto os acessos de Cristália e Montes Claros apresentaram inflorescências simples globóides. Pode-se concluir que os três acessos são equivalentes comercialmente. Entretanto, para produção de sementes, recomenda-se o cultivo do acesso de jambu proveniente do estado do Pará.
The aim of this study was to characterize morphological and agronomic aspects of three Jambu (Spilanthes oleracea L.) accessions under the conditions of North Minas Gerais State, Brazil. The study was carried out in a greenhouse from April to June 2009 in the Institute for Agrarian Sciences of Federal University of Minas Gerais (ICA/UFMG), located in the city of Montes Claros, Minas Gerais, Brazil. The experimental design was completely randomized, with three treatments and eight replicates. Treatments were Jambu accessions (1- from Montes Claros City, Minas Gerais; 2- from Pará State, North of Brazil; 3- from Cristália City, Minas Gerais). Two months after transplanting, the inflorescence length (cm), the length and width of leaves of the third node of each plant (cm) and the fresh and dry matter of shoot and inflorescences (g) were assessed. The color of stems and the type of inflorescences were also characterized. Stem color was visually distinguished, varying from intense purple, Cristália and Montes Claros accessions, to light green, Pará State accession. Inflorescence subtypes were characterized as simple or geminated and elongated or globoid. Jambu accession from Pará State presented the best results for most assessed characteristics. This accession presented elongated simple and, occasionally, both globoid and elongated geminated inflorescences, while Cristália and Montes Claros accessions presented globoid simple inflorescences. It can be concluded that all three accessions are commercially equivalent. However, for seed production, cultivation of Jambu accession from Pará State is recommended.