Seed germination and greenhouse growth of Thymelaea hirsuta seedlings as affected by substrate type and fertilization

Thymelaea hirsuta (L.) is a perennial, evergreen shrub suitable for xeriscaping due to its tolerance to drought and poor rocky soils.
However, its propagation is difficult because of low seed germination capacity and the inability of stem cuttings or microshoots produced in vitro to root.
Aiming to its introduction into the horticultural industry, seed germination was studied, as well as the growth of the produced seedlings in greenhouse conditions under different substrates and fertilizations.
Seeds, placed for germination in a 1:1 (v/v) peat-perlite substrate, at 20°C and 16-h photoperiod, germinated at a higher percentage (32%) after chemical scarification by immersion in concentrated H₂SO₄ for 20 min compared to seeds without pre-treatment (0.5%). Seedlings were acclimatized (95% survival) for one month in greenhouse conditions and then transplanted individually into 0.3-L pots for further two-month growth, in 1:1 peat-perlite, fertilized monthly with 2 g L^‑1 Nutrileaf 60 (5% plant loss). A second transplantation followed in 1.3-L pots, in three different substrates, i.e., 1:1 or 2:1 peat-perlite or 1:1:1 peat-perlite-soil (v/v) and two fertilization doses were applied monthly, i.e., 2 or 4 g L^‑1 Nutrileaf 60. Three months after the second transplantation, seedlings transferred to 1:1 peat-perlite and fertilized with 4 g L^‑1 were the tallest.
More lateral shoots developed from seedlings in 1:1 or 2:1 peat-perlite, regardless of fertilization dose.
Lateral shoot length and canopy diameter were greater in 1:1 peat-perlite with 4 g L^‑1fertilization or in 2:1 peat-perlite regardless of the fertilization dose.

I International Symposium on Protected Cultivation, Nettings and Screens for Mild Climates

A.N. Martini, M. Maragou, M. Papafotiou

chemical scarification, peat, perlite, native xerophytic ornamental plant

https://doi.org/10.17660/ActaHortic.2025.1437.55