Quantitative and qualitative responses of Euphorbia milii and Zamioculcas zamiifolia exposed to different levels of salinity and luminosity

Abstract

The Brazilian Northeast region has favorable climatic conditions for the development of fl oriculture; however, water
scarcity and salinization of part of its water sources act as an obstacle to this activity. In this context, the objective was to test the effects
of increasing levels of salinity in irrigation water on the quantitative and qualitative responses of ornamental species Euphorbia milii and
Zamioculcas zamiifolia, under different light conditions. The study was carried out using an experimental design in randomized blocks, in
a split-split-plot scheme, with fi ve replications. The plants were grown in 7 L pots, undergoing an initial period of acclimatization for 15
days with non-saline water so that their establishment would not be compromised; after this period, the plants were subjected to increasing
levels of salinity in the irrigation water (0.5; 2.0; 3.5; and 5.0 dS m-1) under four light intensities (full sun, 30%, 50% and 70% shading)
for 60 days. The variables analyzed were plant height, stem diameter, belowground and shoot biomass, salinity tolerance and qualitative
analysis. Shading had a greater impact on the qualitative variables of the plants than on the salinity tolerance based on quantitative
variables. The environment with 30% shading is the most favorable for the cultivation of E. milii when using water with low to moderate
salinity. Shading reduces direct radiation damage to Z. zamiifolia leaves and improves the visual quality of this species under high salinity.