Eucalyptus cultivation in Brazil benefits from techniques such as mini cutting; however, adverse climatic conditions in the southern region of the country limit seedling production. This study evaluated the effects of LED lighting (blue, red, combined, and natural) and cultivation environments (greenhouse with and without heating, and conventional nursery) on the propagation of Eucalyptus dunnii. The experiment, conducted in Otacílio Costa, SC, followed a two-factor (4 × 4) design with biweekly data collection from March to September 2024. Variables analyzed included sprout productivity, rooting performance, phytosanitary status (powdery mildew incidence), physiological parameters (photosynthetic rate, stomatal conductance, transpiration), and nutritional content. The results showed that LED lighting and cultivation environments did not affect the incidence of powdery mildew. Rooting was enhanced during winter in the heated mini-tunnel system. Sprout productivity was highest in the mini tunnel (~360 sprouts/m² under red light in winter), while heated environments led to a reduction in sprout production. Physiological variables such as photosynthetic rate and stomatal conductance were improved in the heated mini-tunnel, and transpiration responded to the interaction between light spectrum and environment. The evaluated factors did not cause significant changes in the nutritional profile of the mini stumps. It is concluded that the mini tunnel, particularly when heated during winter, enhances rooting and physiological responses, while red LED light increases sprout productivity. Supplemental LED lighting proved to be a strategic tool for overcoming seasonal limitations in Eucalyptus propagation.

Our objective was to evaluate the effect of a commercial organic fertilizer and substrate conditioners on the production of Eucalyptus benthamii seedlings. Two experiments were conducted with different doses of organic fertilizer (0, 5, 10, 15, 20, and 25 kg m⁻³) and levels of hydrogel (0 and 3 kg m⁻³) and biochar (0 and 30%). In each experiment, plots were divided into two subplots, with one subplot receiving topdressing with mineral fertilizers. At the end of each experimental period, quality, root morphology, and physiological characteristics of the seedlings were assessed. When only the organic fertilizer was applied with substrate conditioners, seedlings exhibited limited growth, averaging 5.02 cm in height and 0.81 mm in stem diameter. Topdressing fertilization combined with higher organic fertilizer doses (20–25 kg m⁻³) enhanced key traits, such as height (up to 24.15 cm) and stem diameter (up to 2.39 mm). Hydrogel and biochar often reduced seedling quality and root development. Some interactions between factors affected certain root variables, but physiological characteristics remained largely unaffected. Overall, even when combined with a substrate conditioner, the commercial organic fertilizer is insufficient to produce high-quality seedlings. Neither hydrogel nor biochar is recommended under our experimental conditions. However, the commercial organic fertilizer shows potential when used with mineral fertilizers and further should be conducted to explore this possibility.