Análise produtiva e econômica da cultura do mamoeiro fertirrigado submetido à diferentes doses de potássio no nordeste paraense.

Abstract

Papaya is a crop sensitive to water stress as well as being recognized as a very demanding crop in potassium, however there is still little research on potassium fertilization via irrigation water in the region where the research is carried out, in addition to both the water factor and the potassium element are correlated with productivity, fruit quality and economic aspects of the production system. In this perspective, this work aims to evaluate the effects of different doses of potassium via fertigation on the yield and quality of papaya fruits Carica papaya L. Cultivar THB. The experiment was implemented in an open field in August / 2018 and will extend until January / 2020, at the Experimental Farm of the Federal Rural University of the Amazon (UFRA), in the municipality of Igarapé-Açu, Northeast Paraense. The soil is classified as Dystrophic Yellow Argisol with medium sandy texture. The climate of the region is of the Amitype by the Köppen classification, hot and humid with average annual temperatures of 25 to 32° C and 2500 mm to 3000 mm of annual precipitation. Climatic data were collected using a portable automatic weather station (Vantage Pro2, Davis). The experimental design adopted was randomized blocks (DBC) with four treatments and four replications. The treatments consist of four doses of potassium (50, 100, 150 and 200% of the recommended). The irrigation system adopted is of the type located by drip, composed of a water tank of 5000 liters, installed near the area of the experiment, with a motor pump set of 1.5 hp., With the irrigation management performed by tensiometry . Each experimental plot, of 42 m2, consists of 7 plants distributed in the spacing of 2.0x2.0x4.0 m (double rows), of which three plants were used in the data collection. The collected data were submitted to ANOVA, Tukey test and regression analysis, the variables adopted were subdivided into two groups: 1- Production data represented by total productivity (PT), commercial productivity (PC), total number of fruits (NFT ) and number of commercial fruits (NFC); 2 - physical and chemical quality of the fruits that were represented by the variables length of fruit (CF), fruit diameter (DF), weight and fruit (PF), hydrogen potential of the pulp (pH), Total titratable acidity (ATT), total soluble solids (SST) and the relationship between total titratable acidity and total soluble solids (ATT / SST). The methodology used in this work to assess the economic feasibility was adapted from Reis (2007), Sousa (2017) and Mendonça et al (2009). It allows us to understand the level of profitability and the benefit-cost ratio. In this work, we applied the dose of 480 kg K2O ha-1 in an area of one hectare of fertirrigated papaya. It resulted in cash flow with a NPV of R$ 27,806.33, an IRR of 48.10% and B/C of 2.01. During the ten month harvest period, the papaya yield reached 57.1 t ha-1, fruit number was 162.3 thousand fruit ha-1, with the dose of 460.4 kg ha-1, the weight of the fruit reached was 418.6 g and the ratio between total soluble solids and titratable acidity reached 13.9. That total costs varied inversely with respect to profits. The best economic performance was identified when applying 480 kg of K2O ha-1 obtaining a total revenue of R $60,376.00 and profitability of R $ 32,404.64. Therefore, from the analysis carried out it is possible to state that the use of technologies in the drip irrigation system is a feasible option considering the area and the observed edaphoclimatic conditions.