Selección de genotipos de cacao (Theobroma cacao L.) con resistencia a escoba de bruja (Moniliophthora perniciosa) en Los Ríos, Ecuador

espanolEl Programa de Mejoramiento del Cacao y el Cafe en el INIAP EET-Pichilingue ha estado estudiando, durante varios anos, los genotipos de cacao mas altos (Theobroma cacao L.) caracterizados por la resistencia genetica a las principales enfermedades, especialmente la escoba de brujas (Moniliophthora perniciosa) Factor limitante para su cultivo en varios paises de America Central y del Sur. El objetivo de la investigacion fue identificar y seleccionar los clones de cacao con una baja incidencia de la enfermedad de la escoba de brujas. Se probaron 21 genotipos (14) resultantes de Amazonas x Amazonas y (4) de Amazonas x Cruces Nacionales. Entre la poblacion derivada de cruces nacionales vs. nacionales, no se encontraron genotipos mostrando resistencia a la enfermedad. Ademas, se selecciono INIAPT 074 del cruce entre CCN 51 x B 60 y TIP 1 y TAP 6 como clones de control. Se evaluaron las siguientes caracteristicas: Numero de mazorcas sanas (MS), Peso fresco (PF), Numero de mazorcas enfermas (ME), Numero de escobas vegetativas (EBveg), Numero de escobas portadoras (EBcojin) y Numero de chirimoyas. Un analisis de componentes principales y un analisis de conglomerados se realizaron utilizando el metodo de Ward y se construyo un dendrograma para determinar la similitud entre las caracteristicas productivas y sanitarias. Se determino que los genotipos resultantes del cruce amazonico x amazonico: INIAPT 527, INIAPT 560 e INIAPT 526 presentaron menor incidencia de escobas y se identificaron como fuentes de resistencia genetica a Moniliophthora perniciosa. EnglishThe Cocoa and Coffee Improvement Program at INIAP EET-Pichilingue has been studying, for several years, higher cocoa genotypes (Theobroma cacao L.) characterized by genetic resistance to major diseases, especially to witch broom (Moniliophthora perniciosa), which is the main limiting factor for its cultivation in several Central and South American countries. The objective of the research was to identify and select those cocoa clones having a low incidence of witch broom disease. 21 genotypes were tested: (14) resulting from Amazonian x Amazonian and (4) from Amazonian x National crossings. Among the population derived from National vs. National crosses, no genotypes showing resistance to the disease were found. In addition, INIAPT 074 was selected from the cross between CCN 51 x B 60 and TIP 1 and TAP 6 were used as control clones. The following features were evaluated: Number of healthy pod (MS), Fresh weight (PF), Number of diseased pod (ME), Number of vegetative brooms (EBveg), Number of bearing brooms (EBcojin) and Number of cherimoya fruits (Fchir). A Principal Components Analysis and a cluster analysis were performed using the Ward method and a dendrogram was constructed to determine the similarity between productive and sanitary characteristics. Was determined that the genotypes resulting from the Amazonian x Amazonian crossing: INIAPT 527, INIAPT 560 and INIAPT 526 presented lower incidence of witch broom, and identified themselves as sources of genetic resistance to Moniliophthora perniciosa.