Resistência de híbridos de Coffea canephora Pierre ex Froehner às raças II e XXXIII de Hemileia vastatrix Berk. et Br

• Ano de defesa: 2011
• Autor(a) principal: Souza Neto, Pedro Nery de
• Orientador(a): Zambolim, Laércio
• Banca de defesa: Zambolim, Eunize Maciel , Oliveira, Antônio Carlos Baião de
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Viçosa
• Programa de Pós-Graduação: Mestrado em Fitopatologia
• Departamento: Etiologia; Epidemiologia; Controle
• País: BR
• Palavras-chave em Português: Ferrugem do cafeeiro; Conilon; Melhoramento genético
• Palavras-chave em Inglês: Coffee rust; Conilon; Breeding
• Área do conhecimento CNPq: CNPQ::CIENCIAS AGRARIAS::AGRONOMIA::FITOSSANIDADE::FITOPATOLOGIA
• Link de acesso: http://locus.ufv.br/handle/123456789/4400

Coffee is one of the main commodities in the world and has, historically, a great importance for the Brazilian agriculture. It is estimated in 2011 that Brazil will produce 43.54 million bags of beneficiated coffee. Coffea canephora Pierre ex Froehner accounts for nearly 26.1% of this amount. Coffee leaf rust caused by the fungus Hemileia vastatrix Berk. et Br. is considered the main disease of robusta coffee. The clones 02 and 83 have been used in the breeding program of C. canephora of the Instituto Capixaba de Pesquisa, Assistência Técnica e Extensão Rural (Incaper). These clones are part of the constitution of clonal varieties released by the Incaper. The clone 02 is one of the genetic material most commonly cultivated in the Espirito Santo state although it is very susceptible to coffee leaf rust. The clone 83 is resistant to the disease. Among the methods available to control the disease, genetic resistance is the best alternative economically. The aim of this work was to characterize the level of resistance of clones 02, 83 and 39 hybrids from the crossing "clone 83 x clone 02" to races II (v5) and XXXIII (v5, v5 or v7, v7.v9) of H. vastatrix. These genotypes are planted at the Fazenda Experimental Bananal do Norte/Incaper, which is located in Cachoeiro do Itapemirim-ES. The resistance to H. vastatrix was tested using coffee leaf disks. The test was carried out following a completely randomized design with three replicates of 16 leaf discs each. The experiment was done in February and April 2011. The resistance components evaluated for each genotype were: incubation period (PI), latent period (PL), percentage of disks with symptoms (DS), percentage of disks with sporulation (DE); percentage of sporulated area (AE) and uredospore production per area (UA). Through cluster analysis was possible to classify the genotypes into four levels of resistance (resistant, moderately resistant, moderately susceptible and susceptible). It was adopted as a measure of dissimilarity the standardized Euclidean distance, and the agglomerative technique the complete linkage. Regarding to resistance to race II in the hybrids obtained from crosses between clones 83 and 02, four (11.1%) were classified as susceptible, fourteen (38.9%) as moderately susceptible, and nine (25%) as moderately resistant and nine (25%) were resistant. The clone 83, used as resistant parent, was classified as moderately resistant and clone 02 (susceptible parent)were classified as moderately susceptible. Regarding the resistance of hybrids to race XXXIII, three (7.9%) were classified as susceptible, sixteen (42.1%) as moderately susceptible, fourteen (36.8%) as moderately resistant and five (13.2%) as resistant. Clone 83 was classified as moderately susceptible to race XXXIII and clone 02 as moderately resistant. It was observed that clones 02 and 83 have horizontal resistance to the disease and the level of its resistance vary according to race inoculated. Part of the hybrids tested also showed variation in resistance level according to the race inoculated. The resistance component that best explained the variation in the levels of resistance was DE. Four hybrids showed vertical resistance to races II and XXXIII. Possibly these hybrids have the resistance factor SH6, because they were resistant to race XXXIII, which has the virulence factors v5,7 or v5,7,9. In conclusion it was found hybrids of C. canephora that can be used for breeding programs aiming at the qualitative and quantitative resistance to coffee leaf rust.