Evaluación de tres niveles de fertilización y su influencia en el crecimiento vegetativo en Cacao (Theobroma cacao L.) clon EETP 800, en La Estación Experimental El Padmi, Zamora Chinchipe

Ecuador is considered the quintessential producer of fine and aroma cocoa from the National type, whose flavor is recognized in the international market, due to its geographical conditions and its richness in biological resources. Nevertheless, cocoa production yields are low, due to the lack of research regarding fertilization and crop adaptation in different areas. Therefore, it is required necessary to test different levels of fertilization during the vegetative phase in Amazonian conditions. In this way, the objective of this study is to evaluate three levels of fertilization (0, 100, and 200 %) and their influence on the chemical conditions of the soil, morphology, physiology, and phenology of cocoa. Fertilization was calculated by an initial soil analysis and based on the nutritional requirements of cocoa in the vegetative stage. The study was carried out in the province of Zamora Chinchipe, in the experimental station "El Padmi" of the National University of Loja. The research was carried out for 5 months, on cocoa plants clone EETP 800 of 20 months of age, using a completely randomized design with three treatments and five replications. The variables studied were pH, electrical conductivity, plant height, shoot length, and crown diameter, which were evaluated every 20 days. Stomatal density, leaf anatomical structure, chlorophyll, number of metameres, leaf area, leaf area index, and phenology were measured at the end of the trial; the trunk cross-sectional area was measured at the beginning and end of the trial. According to the results, no significant differences were found in morphological variables such as height, ASTT, shoot length, number of metameres, crown diameter, AF, and IAF. Regarding chemical parameters of the soil, significant differences were found in pH, the control treatment (T1) registered values higher than 5 during the entire evaluation, while in electrical conductivity no significant results were obtained, however, all the values were less than 1 ds/m. On the other hand, in the physiological variables, differences were found in stomatal density, in the control treatment, a greater number of stomata was obtained: 1031.8 stomata per mm2. Finally, fertilization influences the phenological development of the cocoa crop, since the fertilized plants had an earlier reproductive phase with the appearance of flowers and fruit set, compared to the control plants that were still in full bloom. It concludes the results of this study allowed us to determine the effect of fertilization on the development of the cocoa crop with respect to the absorption of nutrients from the soil, as well as the behavior and adaptability of the EETP 800 clone under Amazonian conditions; this information allows us to provide crop management options for farmers in the area. Keywords: Theobroma cacao L., nutrition, phenology, physiology, and morphology