Morphophysiology of ornamental sunflower plant irrigated with saline water and application of silicon

Abstract

The use of saline water in agriculture is an alternative, especially in regions with water scarcity, such as the Brazilian Northeast semiarid. However, salt stress considerably reduces plant growth and development. In this sense, the objective was to evaluate the morphophysiological responses of the ornamental sunflower irrigated with saline water under application of silicon. The experimental design was entirely randomized conducted in a factorial 4 x 5 with 6 replicates, related to four electrical conductivity of the irrigation water (ECw): 0.5; 1.5; 2.5 and 3.5 dS m-1 five silicon rates: 0, 50, 100, 150 and 200 mg L-1, proceeding to the evaluation of: plant height, stem diameter, number of leaves, absolute and relative growth rates, initial fluorescence, maximum fluorescence, variable fluorescence, maximum efficiency of the photochemical process in FSII, potential quantum yield of photosystem II, stomatal conductance and instant efficiency in the use of water. The gradual increase of ECw reduces growth, chlorophyll fluorescence a and stomatal opening of the ornamental sunflower plants. The application of silicon above 100 mg L-1 promotes a decrease in ornamental sunflower stomatal conductance. It is recommended to irrigate ornamental sunflower plants with water of 0.5 dS m-1 associated with the application of 100 mg L-1 of silicon.