Cultivo de jambu em sistema hidropônico: concentração iônica e aporte de nitrogênio em diferentes genótipos

Abstract

Jambu is an unconventional vegetable from the Amazon region, which has significant economic potential, due to the presence of epilantol, a substance that has numerous applications in industry. However, studies on jambu genotypes in hydroponic system with the input of nutrients in the nutrient solution are incipient. In this sense, this work aimed to evaluate the performance of jambu genotypes in hydroponics, with different ionic concentrations of the nutrient solution and nitrogen supply. Therefore, three experiments were carried out in a completely randomized design. In the first, the productive performance of eight jambu genotypes (UFR-1, UFR-2, UFR-3, UFR-4, UFR-5, UFR-6, UFR-7 and UFR-8) collected in different locations in the state of Pará. For the second, six ionic concentrations (25, 50, 75, 100 and 125% of the ionic strength) of the solution proposed by Hoagland & Arnon were applied. In these two, the growth, production and gas exchange of the plant were evaluated. For the third, six concentrations of nitrogen (11, 13, 15, 17, 19 and 21 mmol L-1 of N) in the nutrient solution were tested. It was evaluated the growth, yield, postharvest quality, photosynthetic pigments, spilantol concentration in jambu organs, as well as the feasibility of the SPAD index to assess the nitrogen status in jambu leaves and predict production. The genotypes showed different behavior between and within the same species in relation to the evaluated growth, productive and physiological characteristics. The genotypes of the species A. oleracea, in addition to the capacity to accumulate fresh mass of the aerial part, have a high potential for production of inflorescences, with the genotypes UFR-2 and UFR-4 standing out for their greater capacity in the production of fresh mass of the shoot aerial part and inflorescences, respectively. As for the effect of ionic concentrations in the nutrient solution, the 125% concentration of the formulation proposed by Hoagland & Arnon promoted greater growth and production of jambu plants. The contribution of nitrogen in the nutrient solution alters the growth, production and quality of jambu plants. Thus, supplies of 21 mmol L-1 of N in the nutrient solution resulted in a higher concentration of N in the leaves, which promoted greater production of aboveground and inflorescence biomass, photosynthetic pigments and spilantol content in plant organs. In addition, there was a linear and positive correlation between the SPAD index and the nitrogen content, total chlorophyll and the accumulation of biomass in jambu, presenting, therefore, potential to be used in the diagnosis of the nutritional status of N and in predicting production.