ABSTRACT
The use of biostimulants may mitigate the deleterious effects of salt stress on plant growth and physiological variables. Thus, the present study aimed to evaluate the growth, physiology, organic solutes, and visual characteristics of two tropical ornamental species (Celosia argentea and Catharanthus roseus) cultivated with brackish waters and treated with Ascophyllum nodosum extract. The experiment was performed in greenhouse conditions. The experimental design was a complete randomized block arranged in a split-plot scheme. The plots comprised three levels of electrical conductivity of the irrigation water (ECw - 0.5, 2.5, and 4.5 dS m-1), the subplots four concentrations of algae extract (0, 400, 800, and 1200 mg L-1), and the sub-subplots two tropical ornamental herbaceous species [C. argentea and C. roseus]. The salinity of the irrigation water negatively affects the morphological and physiological characteristics of the two species studied, mainly C. roseus. Irrigation with water up to 2.5 dS m-1 favored visual quality and increased the purchasing preference for C. argentea. The use of intermediate concentrations (400 mg L-1) of algae extract (A. nodosum) promoted partial mitigation of the effects of salt stress on biomass production and leaf gas exchange, especially for C. argentea, but these positive responses decreased or disappeared with the intensification of salt stress and the increase in algae extract concentration.
Key words:
Ascophyllum nodosum
; irrigation; ornamental plants; photosynthesis; salt stress
HIGHLIGHTS:
Salinity negatively affects the morphophysiology of Catharanthus roseus.
Salinity up to 2.5 dS m-1 favors the visual quality of Celosia argentea.
Extract of seaweed Ascophyllum nodosum partially mitigates the harmful effects of salt stress.
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Vertical bars represent the standard deviation (n=4); ** and * - Significant at p ≤ 0.01 and p ≤ 0.05, respectively, by the F-test. Lowercase letters differentiate the salinity levels using the Tukey’s test (p ≤ 0.05)
Vertical bars represent the standard deviation (n=4); ** and * - Significant at p ≤ 0.01 and p ≤ 0.05, respectively, by the F-test. Lowercase letters differentiate the salinity levels using the Tukey test (p ≤ 0.05)
Vertical bars represent the standard deviation (n=4); ** and * - Significant at p ≤ 0.01 and p ≤ 0.05, respectively, by the F-test. Lowercase letters differentiate the salinity levels using the Tukey test (p ≤ 0.05)