Assessment of Various Gibberellic Acid Concentrations on Seed Germination and Seedling Growth of Chilgoza (Pinus gerardiana Wall. ex D. Don)

Chilgoza (Pinus gerardiana) forests naturally exist on the highest elevations of the Himalaya Mountains in the provinces of Paktia, Kunar, Nangarhar, Nuristan, and Paktika in the southeast of Afghanistan. These natural chilgoza forests provide a sizable source of income for the people living in these areas. The spread and natural regeneration of chilgoza pine forests is declining in the natural environment as a result of overharvesting, erratic annual seed production, and prolonged dormancy; therefore, it is necessary to find an effective method to enhance seed germination and seedling growth. Different Gibberellic Acid (GA₃) hormone concentrations (50 ppm, 75 ppm, and 100 ppm), the removal of the seed coat, and control (untreated) treatments were used to conduct an experiment for this study. For each treatment, seedling growth parameters and the percentage of seeds that germinated were examined. The results showed that the T₄ treatment had the highest average length of seedling, shoot, and root, measuring 13.34 cm, 8.1 cm, and 8.4 cm, respectively; whereas the T₁ treatment had the shortest average lengths of seedling, shoot, and root, measuring 11.22 cm, 6.5 cm, and 6.2 cm, respectively. The greatest percentage of germination (78.66%) was observed in T₄ (100 ppm), whereas the lowest percentage (26%) was documented in T₁ (Control). The highest average number of leaves was recorded in T₄ (22.25) and the lowest in T₁ (15.02) treatment. The results indicated that treating chilgoza pine seeds in a 100 ppm solution of GA₃ for 24 hours enhances both the seed germination and sprouting seedling growth.