Tolerância à salinidade em espécies ornamentais tropicais cultivadas sob aplicação de extrato de algas

Abstract

The use of a seaweed extract-based biostimulant can mitigate the harmful effects of salt stress on tropical ornamental species with different degrees of tolerance to salinity. Given the above, the objective was to evaluate the responses in growth, dry mass accumulation, leaf morphology and the physiological indices involved in salinity tolerance in tropical ornamental species cultivated under salt stress and application of algae extract. The experiment was carried out from June to August 2021, carried out in the experimental area of the Agrometeorological Station, belonging to the Department of Agricultural Engineering of the Federal University of Ceará. The experimental design was in randomized blocks, arranged in sub-subdivided plots, the plots being formed by three levels of electrical conductivity of the irrigation water - ECw (0.5, 2.5 and 4.5 dS m-1), classified as low, moderate and high salinity, respectively, the subplots by four concentrations of algae extract (0, 400, 800 and 1200 mg L-1) and the subplots corresponded to two species of tropical ornamental plants: Catharanthus roseus and Celosia argentea. Aspects of vegetative growth, dry mass accumulation, leaf morphology, physiological indices and sensory and visual characteristics of the species were evaluated. Salinity negatively affects the morphophysiological characteristics and visual quality of both species, mainly C. roseus. ECw of up to 2.5 dS m-1 favors better visual quality and greater purchase preference in the species C. argentea. The use of increasing concentrations of seaweed extract (Ascophyllum nodosum) does not attenuate the effects of salt stress on the growth and leaf morphology of ornamental species C. argentea and C. roseus. However, the intermediaries concentrations of the algae extract (400 mg L-1) promote partial mitigation of salt stress in the physiological indexes of the species evaluated in the study.