Optimizing Germination and Seedling Vigor in Verbascum thapsus L.: Synergistic Effects of Temperature, Media Composition, and Sowing Depth in Controlled Germination

Author(s)

Ammar Majid AL ZEARA , Betul AKIN , Sanaa Khalaf Ghabish AL HAFEDH ,

Download Full PDF Pages: 01-12 | Views: 14 | Downloads: 4 | DOI: 10.5281/zenodo.15801128

Volume 9 - June 2025 (06)

Abstract

This study, conducted at the Plant Tissue Cultures Laboratory of Kütahya Dumlupınar University's Biology Department, optimised germination protocols for the medicinal plant Verbascum thapsus L. using a completely randomised block design with four replicates. ANOVA and Tukey's HSD test (α = 0.05) were used for data analysis. Three experimental approaches were employed: standard Petri dish germination, tissue culture-based germination (MS medium), and stratified substrate sowing. Seeds were exposed to varying temperatures (16/22 °C, 25°C), media compositions (pH 5.0–6.5; agar 0.6–0.8%; GA₃ 0–50 ppm), and sowing depths (0.1–2.0 cm) to assess germination parameters and seedling quality. Results indicated that 25°C was superior to 16/22 °C, enhancing both germination rates (58.33%) and seedling vigor index (SVI: 443.38). Optimal MS medium composition was pH 6.0 with 0.6% agar and 25 ppm GA₃ (93.33% germination), with higher GA₃ inhibiting growth. Acidic pH (5.0) promoted root elongation (9.77 cm) but reduced germination. Stratified sowing showed drastically reduced germination (78.89% to 7.78%) and SVI (618.50 to 6.64%) with increasing depth; surface-sown seeds (0.1 cm) exhibited the shortest mean germination time (4.65 days) and best seedling development. Optimal conditions were found to be 25°C with pH-adjusted (5.0–6.0), low-agar (0.6–0.7%) MS medium, combined with shallow sowing. Deep sowing (>0.3 cm) significantly impaired germination and seedling emergence. The study concludes that V. thapsus propagation is maximised under 20–25°C, shallow sowing (≤0.3 cm), and MS medium with pH 6.0–6.5, 0.6–0.7% agar, and 10–25 ppm GA₃. These findings provide valuable insights for improved cultivation and suggest future research should validate these protocols in field conditions and investigate soil-microbial interactions.

Keywords

Verbascum thapsus, Germination Temperature, Tissue Culture, Sowing Depth, Seed vigor.

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