Biomass and spilanthol content of hydroponic jambu as a function of nitrogen supply¹

Biomassa e teor de espilantol de jambu hidropônico em função do fornecimento de nitrogênio

ABSTRACT

Jambu (Acmella oleracea) is a typical culinary vegetable from Northern Brazil that has gained increased demand and recognition due to its sensory and bioactive properties attributed to the presence of spilanthol. Strategies for plant management have been explored; however, the influence of N supplementation on spilanthol biosynthesis in jambu in a hydroponic system is unknown. Thus, this study aimed to evaluate the effect of N on biomass production, photosynthetic pigments, leaf nitrogen concentration, and spilanthol content in jambu cultivated hydroponically. The plants were subjected to six concentrations of N in the nutrient solution (11, 13, 15, 17, 19, and 21 mmol L^-1), using a completely randomized design with four replications, each consisting of one plant. Fresh and dry biomass of inflorescence, shoot (leaves and stems), and root, N and pigment content in the leaves, and spilanthol content in different plant organs were evaluated. The N concentrations positively affected biomass production, photosynthetic pigments, leaf N concentration, and spilanthol content in jambu inflorescence, shoot, and root. The supply of 21 mmol L^-1 N in the nutrient solution resulted in a higher concentration of N in the leaves, leading to increased production of photosynthetic pigments, shoot biomass, and inflorescence. Conversely, a moderate supply of 17 mmol L^-1 N resulted in a higher synthesis of spilanthol in the organs of the jambu plant. Therefore, appropriate nitrogen supplies should be considered an indispensable tool for the nutritional management of jambu cultivated in hydroponic systems.

Key words:
Acmella oleracea; cultivation without soil; secondary metabolite; nutrition

HIGHLIGHTS:

Nutritional disorder due to low nitrogen supply does not stimulate spilanthol biosynthesis in jambu.

Spilanthol biosynthesis in jambu is stimulated by nitrogen supply.

Higher concentrations of spilanthol were identified in the inflorescences, followed by the shoot (leaf and stem) and root.