Viabilidade agronômica de substratos orgânicos alternativos para a produção de mudas de maracujazeiro-amarelo

Abstract

The use of organic inputs in agricultural substrates is an alternative to reduce production costs and improve the development of plants, such as the yellow passion fruit (Passiflora edulis Sims f. Flavicarpa Deg,) with prominence for being advantageous among fruit trees and still having considerable socioeconomic importance in the Amapá. Thus, the objective was to evaluate the agronomic viability of the use of alternative organic residues in the production of yellow passion fruit seedlings aiming at subsidies to the culture in the Amapá. The experiment it was developed at the Universidade Federal do Amapá, Campus Mazagão, Mazagão, AP, with 8 substrates or formulations, being: S1 - Biomix commercial substrate; S2 - bovine manure; S3 - bubaline manure; S4 - decaying açaí; S5 - organic compound based on açaí seed; S6 - 50% soil + 50% bovine manure; S7 - 50% soil + 50% bubaline manure; and, S8 - 50% soil + 50% crushed fresh açaí seed. The experimental design was completely randomized, with 4 replications and 2 experimental units per plot. Yellow passion fruit seeds 'Sol' were used, sown in polyethylene bags with capacity of 3 dm3 of substrate, at a depth of 2 cm, with 2 seeds per container, in equidistant holes. At 35 and 56 days after sowing, the leaf area of the plants (AF) (cm2) and the total dry mater (FST) (g) were determined, using the data between samples to determine the rate of apparent assimilation (TAA) (g cm2 day 1); with the data of the final evaluation, the specific leaf area (AFE) (cm2 g-1), the leaf weight ratio (RPF) and the part root shoot (R/PA) were also calculated. The levels of photosynthetic pigments, chlorophyll a, chlorophyll b, total chlorophyll and total carotenoids were also evaluated. Greater AF and FST were observed in treatments with pure bovine manure or mixed with the soil and also with pure bubaline manure. The highest averages of AFE and RPF were obtained with compost based on açaí seed, indicating changes in the photosynthetic leaf apparatus of the plants, despite having lower growth, in which the plants had higher amounts of photosynthetic pigments in the leaves, as occurred with the plants on the commercial substrate. It was evident that bovine and bubaline manure isolated or composing the cultivation substrate provide better vegetative performance of yellow passion fruit seedlings, with a direct positive influence on the leaf area of the plants. Yellow passion fruit seedlings develop changes in the physiological growth indices and in the synthesis of photosyntheti pigments when the substrate composition is not adequate and/or nutritionally sufficient for the plants. The mix of soil and bovine or bubaline manure is agronomic and economically efficient for the production of quality yellow passion fruit seedlings