Evaluación de genotipos ecuatorianos de Capsicum spp. ante infestaciones de Bemisia tabaci

The genus Capsicum, native to tropical and subtropical America, belongs to the Solanaceae family, which includes commercially important vegetables such as chilies and green peppers. The silverleaf whitefly Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae), causes losses to vegetables including Capsicum species. Among the alternatives of pest control, an effective, economical, and environmentally compatible method is the resistance of the host plant. Infestation by B. tabaci was evaluated in 73 Capsicum genotypes, corresponding to the species C. annuum, C. baccatum, C. sinense, C. frutescens and C. pubescens from an Ecuadorian genebank. Eighty-four percent of the C. baccatum genotypes evaluated showed the highest population densities of B. tabaci, while all the genotypes of C. sinense and C. frutescens had the lowest values (p < 0.05). The non-preference of adults and the scarce oviposition of B. tabaci on genotypes of C. sinense and C. frutescens suggests resistance due to antixenosis. These results could guide breeding programs for the resistance of Capsicum species to B. tabaci infestations.El género Capsicum es nativo de América tropical y subtropical, pertenece a la familia Solanaceae e incluye ajíes y pimientos, que son hortalizas comercialmente importantes. La mosca blanca Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) ocasiona pérdidas en hortalizas incluyendo especies de Capsicum. Entre las alternativas de control de plagas, un método eficaz, económico y ambientemente compatible es la resistencia de la planta hospedera. Se evaluó la infestación por B. tabaci en 73 genotipos de Capsicum nativos de Ecuador, correspondientes a las especies C. annuum, C. baccatum, C. chinense, C. frutescens y C. pubescens, provenientes de un banco de germoplasma ecuatoriano. El 84% de los genotipos de C. baccatum evaluados mostraron las mayores densidades poblacionales de B. tabaci, mientras que los menores valores los tuvieron todos los genotipos de C. sinense y C. frutescens (p < 0.05). La no preferencia de adultos y la escasa oviposición de B. tabaci sobre genotipos de C. sinense y C. frutescens sugiere resistencia por antixenosis. Estos resultados podrían orientar programas de mejoramiento genético para la resistencia de especies de Capsicum ante infestaciones por B. tabaci

Effect of organic and chemical fertilization on the onion crop (Allium cepa L.)

The bulb onion (Allium cepa L.) is a vegetable widely cultivated and in high demand in national and international markets. Due to the risks that the indiscriminate use of agrochemicals represents for human health and the environment, the present study aimed to make a comparative analysis of the effects of organic vs chemical fertilization currently used in the cropping of red hybrid bulb onion (Eureka). Three organic fertilizers (Zumsil®, ComCat® and EcoFungi®) were compared to three chemical fertilizers (15-15-15®, Muriate of Potash® and Nitrofoska®). The response variables were: plant height at 30 and 60 days after transplanting (DAT), length, diameter and average weight of bulbs, yield in tons per hectare and the relationship between height at 30 and 60 DAT. The experiment was carried out under a completely randomized design with four replicates, seven treatments and 28 experimental units. The statistics used include an analysis of variance and a Canonical Biplot that allowed to obtain groups of variables and to determine their correlation with each one of the treatments. Additionally, a marginal analysis of dominant treatments was performed. Positive response of variables was strongly associated with organic fertilizers. From the economic point of view, the ComCat® organic fertilizer represented an ecological alternative with excellent benefits for the producer. This research is in line with the trends for agrochemical-free foods