DESENVOLVIMENTO DA vinagreira (Hibiscus sabdariffa L.) SOB DIFERENTES FONTES DE POTÁSSIO

Abstract

The roselle plant (Hibiscus sabdariffa L.) is a traditional family farming culture in Maranhão. Being considered an unconventional vegetable cultivated by traditional communities, especially quilombolas, and thus characterized as cultural and gastronomic component. However, there is little information on potassium fertilization for this crop in Brazil. The objective of this work was to evaluate the roselle productive performance, submitted to different seasons of harvests and potassium sources, considering the variables of growth, production and soil fertility. The experimental field stage was implemented from June to October 2018, under conditions of a dystrophic Yellow Latosol typical soil of São Luís - MA. This step was carried out in random blocks with five repetitions per treatment, being: a) for the variables plant height, lateral branches number, lateral branches average length, plant neck diameter and lateral branches dry mass, in an arrangement factorial between seven potassium sources, potassium chloride and potassium polysulfate in different proportions and six harvest ages (30, 45, 60, 75, 90, 105 DAT); b) for the variables dry mass and potassium content of the aerial part, evaluated exclusively at 105 DAT, a factorial arrangement was adopted between seven potassium sources and three periods of harvest (30 and 75; 40 and 90; 60 and 105 DAT) ; c) and for soil fertility variables (pH, K +, P, Ca2 +, Mg2 +, H + Al and S), a simple randomized block design was adopted considering only the seven potassium sources at 105 DAT. The results showed that there were significant effects between the ages of the plant and the variables height, number and average length of the lateral branches, neck diameter and lateral branches dry mass of plant, considering the quadratic mathematical model. The later harvest period (60 and 105 DAT), provided greater dry mass accumulation, with lower potassium content in the aerial part of plant. And among the soil fertility variables, evaluated at 105 DAT, there was only influence of potassium sources on the available potassium content, it is concluded that potassium polysulfate, applied exclusively or associated with potassium chloride, is an alternative for potassium fertilization considering the roselle production development and the residual effect of the fertilization on soil and the harvest period, represented by 60 and 105 DAT, that provided a better productive performance of crop.

KEYWORDS: potassium fertilization, harvest, Hibiscus sabdariffa L., potassium polysulfate