The Difficulty of Chadian Forest Tree Seed Germination: Overcoming Physical Dormancy

الملخص

High-quality tree seeds are essential for restoring degraded forests and achieving natural resource regeneration objectives. Chad faces challenges such as food and nutrition insecurity, low-income levels, and declining natural resources due to rapid population growth. Reforestation of degraded lands could help address these issues. Chad has committed to reforesting 500,000 ha of deforested land by 2026. Chad's forest and woodland seed value chains have underdeveloped markets and few private sector actors. The study found that physical dormancy is a known mechanism for Acacia species, but the flame treatment method is less well-known. Sand burial could break dormancy associated with physical and mechanical dormancy and hardseededness class 1 species. Washing cycles are effective for seeds with physical/abraded and combinational dormancy with treatment. The study provided the first validated protocols for germinating important dryland species with physical dormancy, which is mostly legumes with erect seeds with small projections. The use of specific methods for removing the hard seed coat is crucial in Savanna-Mosaic of Chad for seedling and nursery establishment. The optimal method depends on the tree species and should be used carefully during the rehabilitation phase of reserved forests in Southern Chad. The germination of forest tree seeds can be affected by physical dormancy, root trajectory, and early radicle desiccation. Opening the hard seed coat artificially can lead to high germination rates, but imposed dormancy should be removed carefully. Mechanical removal of the seed coat increased the germination percentage of E. guineensis, while immersion in hot water resulted in low germination.