Plant growth and micronutrient contents of yellow passion fruit subjected to organic fertilization

The utilization of organic fertilizers to enhance plant growth has witnessed a surge in recent years. This is attributed to the beneficial effects of organic matter on intensely cultivated soils, coupled with the high costs of mineral fertilizers for farmers. Here, we conducted an experiment to assess the impact of organic compound doses on the growth and nutritional status of passion fruit. The experiment was conducted in a greenhouse at the Universidade Federal Rural da Amazônia, in Belém, Pará State, Brazil. The experimental design was completely randomized with five treatments and four replications. Each experimental plot comprised a vase with a volume of 3.6 dm3 of soil and a yellow passion fruit seedling (Passiflora edulis f. flavicarpa Deg.). Five rates of organic fertilizer (0%, 15%, 30%, 45%, and 60%) were tested out of the total volume of the substrate. The organic fertilizer (pH = 6.9, N = 15.2 g kg-1, and C = 109.7 g kg-1) was prepared by mixing 10% chicken manure, 20% duck manure, 15% cassava bark, 15% cassava leaf, 15% bean straw, 15% rice husk, and 10% corn cob. The optimal results of stem diameter, number of leaves, and total dry mass were achieved with a dose of 60% of the organic fertilizer at 97 days. The content and accumulation of micronutrients in the foliar tissue of yellow passion fruit plants followed the descending order: Fe˃B˃Mn˃Zn˃Cu. It is recommended a dose of 60% of organic fertilizer to be used for the production of yellow passion fruit seedlings in the edaphoclimatic conditions of the Brazilian eastern Amazon.