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Plant Science Today (PST)

Research Articles

Vol. 13 No. 3 (2026)

Optimising germination of Verbascum speciosum Schrad. seeds: Effects of temperature, salinity and pH for sustainable cultivation

DOI
https://doi.org/10.14719/pst.12575
Submitted
3 November 2025
Published
08-07-2026 — Updated on 25-09-2026
Versions

Abstract

Defining the germination niche of Verbascum speciosum Schrad., a medicinal pioneer species for semi-arid rangeland restoration, is crucial for sustainable propagation. This study evaluated the effects of temperature (10–25 °C), salinity (0–10 g L-1 NaCl) and pH (2–9) on seed germination using seeds from two Iranian populations, Zarand and Kohbanan, in Kerman Province. Seeds were incubated in darkness using sequential single factor experiments with 3 replicates and 90 seeds per treatment. Final germination percentage was analysed by one-way analysis of variance (ANOVA followed by Tukey’s honestly significant difference (HSD) test at p < 0.05. Germination showed a bell-shaped thermal response, peaking at 15 °C, with 93.6 ± 2.1 % in Zarand and 83.0 ± 3.5 % in Kohbanan, while germination was completely inhibited at 25 °C. Increasing salinity significantly reduced germination and delayed seed germination, with near-complete inhibition at NaCl concentrations of 7.5 g L-1 or higher. Germination occurred across a pH range of 3.5 to 9, with the highest germination at neutral pH 7, whereas extremely acidic conditions (pH 2) almost completely inhibited germination. These results indicate a narrow thermal optimum, moderate salinity sensitivity and broad pH tolerance in V. speciosum, supporting cool-season establishment in autumn microsites and providing practical guidance for restoration and cultivation in semi-arid rangelands.

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