Teores de elementos minerais em folhas de Celosia Argentea e Catharanthus Roseus sob estresse salino e adição de bioestimulante

Abstract

In periods of water scarcity in the Brazilian semi-arid region, it is common to use groundwater with electrical conductivity ranging from 2.0 to 6.0 dS/m for irrigation. However, the use of these waters affects plant development, causing negative effects on nutrient absorption and plant productivity. A strategy for this problem is the use of tolerant genotypes linked to techniques that reduce the effects of saline stress. In this sense, the use of biostimulant produced from seaweed extracts in agriculture can be an alternative as a technique to mitigate salt stress in plants. Thus, the present study aimed to evaluate the content of foliar mineral elements of ornamental plants Celosia argentea and Catharanthus roseus cultivated at different levels of electrical conductivity of irrigation water and concentration of seaweed extract. The experiment was carried out in a protected environment in 700 mL plastic pots filled with substrate in a randomized block design, arranged in subdivided plots, with the plots formed by two levels of electrical conductivity of irrigation water - ECa (0.5 and 2. 5 dS m-1), the subplots by four concentrations of seaweed extract (0, 400, 800 and 1200 mg L-1) and the subsubplots corresponded to two species of tropical ornamental plants (Catharanthus roseus and Celosia argentea). Leaf samples were collected to carry out the chemical analysis of the plant tissue, analyzing the variables: nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), sulfur (S), chlorine (Cl), sodium (Na), sodium/potassium ratio (Na/K) and soil electrical conductivity (ECes) at the end of the experiment. Nitrogen, phosphorus and potassium contents were influenced by salinity and biostimulant effects. There was an increase in N and K foliar contents with the increase in salinity and in the biostimulant for the species C. argentea. The effect of salinity negatively influenced the absorption of P. The species C. roseus showed greater sensitivity to saline stress. The contents of all mineral elements as well as the Na+/K+ ratio were influenced by the effects of the electrical conductivity of the irrigation water and the seaweed extract biostimulant. Leaf levels of N and K increased with increasing salinity and biostimulant for the species C. argentea; foliar contents of P, Ca and Mg were reduced with increasing salinity and biostimulant for both species. The species C. argentea showed greater tolerance to salinity, while the species C. roseus was more sensitive to salt stress.