G. Lykokanellos¹, D. Zoumadakis¹, N. Semkova², V. Ivanova²
1 Department of Agriculture, Laboratory of Floriculture – Landscape Architecture, University of Patras, 30200 Messolonghi, Greece
2 Department of Horticulture, Faculty of Horticulture, Agricultural University, 4000 Plovdiv, Bulgaria
(Manuscript received 21 May 2025; accepted for publication 3 September 2025)
Abstract. Shading significantly affects the growth, morphology, and flowering of Schlumbergera spp., commonly known as “Christmas cactus,” an epiphytic ornamental species native to the understory of Brazilian rainforests. This study evaluated the effect of four shading levels – 0% (control), 30%, 50%, and 70% – on the vegetative development, chlorophyll content and integrity, photosynthetic activity, and reproductive performance of Schlumbergera under controlled greenhouse conditions in Messolonghi, Greece, from August 2023 to February 2024. The experiment was conducted in a completely randomized design with three replications of ten plants per treatment. Weekly data were collected on shoot length, stem thickness and coloration, number of floral buds, and total flower count. Physiological assessments included net photosynthetic rate (µmol m⁻²s⁻¹) and chlorophyll absorbance at 665 and 648 nm. Results revealed that moderate shading (30% and 50%) significantly enhanced cladode compactness, chlorophyll a absorbance consistency, and floral induction (p < 0.01, Tukey’s HSD). Plants under 30% shading exhibited the highest chlorophyll a absorbance and the most homogeneous vegetative biomass, whereas the control group (0%) displayed photoinhibition symptoms despite elevated photosynthetic rates. Deep shade (70%) induced etiolation and poor floral development. These findings suggest that 30% shading significantly optimizes morpho-physiological performance in Schlumbergera and should be considered best practice for commercial greenhouse production.