The central Andean region in South America is considered the primary center of diversity of Capsicum species. From August – November 2018 a wilting and root rot of bell pepper plants was observed w...

Seed viability of domesticated and cultivated Capsicum species: Capsicum annuum L., Capsicum baccatum L., Capsicum chinense Jacq., Capsicum frutescens L., and Capsicum pubescens Ruiz and Pav. was tested by the tetrazolium method. The seeds were soaked in three tetrazolium salt solutions of 1, 0.5 and 0.2%, and temperature conditions of 30 - 35 C for 3 h. The percentage of seeds stained in relation to the total number of seeds was evaluated. To estimate germination, the seeds were subjected to chemical treatments with gibberellic acid (GA3) at doses of 0, 100, 200, 300, and 400 mg L-1 at room temperature for 24 h. The germination rate was estimated, while plant height was evaluated at 10, 20 and, 30 days after sowing (DAS). Capsicum seed viability fluctuated between 52.44% and 97.11%. The highest percentage of viability was obtained with the 1% dose of tetrazolium (81.63%), while the 0.2% dose resulted in the lowest average value (63.7%). In addition, C. annuum, C. baccatum and C. chinense showed high staining patterns, while most of the observed patterns in C. frutescens corresponded to non-viable seeds. After GA3 application, average seed germination was 100% in C. chinense; 75.6% in C. baccatum; 73.32% in C. annuum; and 61.5% in C. frutescens. However, the application of GA3 did not cause an additional effect on the germination of Capsicum seeds. The highest plant height at 30 DAS was observed in accessions of C. annuum (9.08 cm), while C. chinense presented the lowest value (4.49 cm).

"Topito" sweet pepper is considered one of the main vegetables in the colombian Caribbean region due to tradition and daily consumption in at least six of the seven continental departments of the Atlantic coast. Development of research lines for genetic improvement to obtain increased production cultivars are highly relevant. To determine the morphological and agronomic variability of the sweet pepper germplasm collection in the colombian Caribbean to use it for genetic improvement, a characterization with 45 qualitative and quantitative descriptors for Capsicum spp. in 125 accessions for the colombian Caribbean was carried out. A complete randomized design was used for nine plants. Data analysis was done through Ward's classification method using Gower's distance. Results showed polymorphism in 19 qualitative characteristics, with 67.9% variability. Data mixed analysis allowed to separate Capsicum genus species of the collection; likewise, collection phenotypic variability has potential for using in genetic breeding programs for desirable characters such as fruit quality, plant architecture and production.

Con el objetivo de determinar las diferencias morfo-agronómicas y de calidad, y la diversidad genética entre 14 variedades de arroz de América Latina con sus respectivas líneas de origen, se estableció un estudio (Bloques completos al azar, con 28 genotipos, tres repeticiones y dos siembras en el tiempo), en el cual se midieron 25 variables morfo-agronómicas y de calidad de grano. El análisis molecular se hizo mediante un arreglo de 96 marcadores tipo SNP de alta capacidad de discriminación para arroces Indica. El análisis estadístico se hizo combinando los datos de las dos siembras porque no hubo diferencias estadísticas entre ellas. Además, se analizaron en conjunto los datos moleculares con los morfo-agronómicos y de calidad, usando el índice de Gower para generar una matriz de similitud. Mediante el programa SAS se analizaron los datos agronómicos y moleculares tanto en forma independiente como en conjunto. Los resultados mostraron que, de las 14 variedades, ocho se agruparon con su línea de origen y hubo una variedad que se agrupó con una línea hermana de su ancestro. Los resultados fueron consistentes cuando el análisis de datos se hizo independientemente o combinado. Dada la amplia diversidad encontrada dentro de las variedades y que ninguna fue homocigota al 100 % no se pudieron establecer los perfiles genéticos distintivos de ellas, por lo que se debe hacer la purificación de las variedades para establecer su huella genética.

El Grupo de Investigación Mejoramiento Genético Vegetal Tropicales de la Universidad del Magdalena posee varias introducciones de maíz originarias del Caribe colombiano; se seleccionaron 13, las cuales fueron donadas por la Universidad Nacional de Colombia sede Palmira, con pasaporte del departamento del Magdalena. Las introducciones se caracterizaron para estudiar la variabilidad fenotípica. La siembra se realizó en el Centro de Desarrollo Agrícola y Forestal de la Universidad del Magdalena, ubicada en la ciudad de Santa Marta; bajo un diseño de bloques completos al azar con tres repeticiones; se sembraron 20 plantas por introducción y se evaluaron 5 de ellas por unidad experimental y se estudiaron 28 caracteres morfológicos. Se realizó un análisis de varianza, de frecuencias, de componentes principales, discriminante y de agrupamiento. Este mostró diferencias significativas entre introducciones para la mayoría de las variables, lo que se considera un indicador de diversidad. Los análisis de componentes principales y de agrupamiento, diferenciaron a las muestras en cinco conjuntos; al interior de los grupos se presentó una diferencia gradual y continua de caracteres. Los genotipos mostraron similitud genética con la introducción 91, el mayor distanciamiento genético se dio con el híbrido comercial Synko. El agrupamiento de las introducciones por municipio, mostró la tendencia de ubicar el desplazamiento de las introducciones, desde el municipio de Fundación como punto de partida.

Root rot caused by the oomycete Phytophthora cinnamomi (Pc) is the main phytosanitary limitation in avocado production in many regions of the world. Management of this disease has been based on epidemiological studies and integrated crop management, where resistant rootstocks are considered one of the main options. This study aimed to evaluate the resistance levels of six avocado genotypes from the Colombian Germplasm Avocado Collection (CCGA) to Pc under nursery conditions, as these genotypes are known to be promising for use as rootstocks. Each genotype was propagated by cloning and evaluated with and without the pathogen in conformity with epidemiological, physiological, and histological parameters in a randomized complete block experimental design with three replicates per treatment, with each replicate being represented by three plants as an experimental unit. The area under the disease progress curve (AUDPC) and the apparent rate of infection (rAUDPC) discriminated against four levels of genetic resistance to the pathogen. The AUDPC in inoculated plants of each genotype was related to the degree of root necrosis (RN), with significant reductions in photosynthetic capacity, stomatal conductance (gs), and biomass loss in root and foliage in the most susceptible genotypes. Histological analysis of roots confirmed the ability of Pc to invade and damage roots in different avocado genotypes. At the same time the formation of tyloses was identified as a mechanism of histological response to infection. The selections CCGA0143, CCGA0080, CCGA0122, and Duke-7 are proposed as elite genotypes resistant to Pc, due to reduced root damage and etiological performance to infection under nursery conditions.