Seed Quality and Seedling Production of Sequoia sempervirens, Sequoiadendron giganteum, and Pseudotsuga menziesii

Given the ecological significance and potential for afforestation and carbon sequestration of these species, this study contributes to optimizing nursery practices for successful regeneration and conservation efforts. Thus, this research assessed the physical and physiological seed quality and seedling production of Sequoia sempervirens, Sequoiadendron giganteum, and Pseudotsuga menziesii. For seed characteristics the following were tested: (I) Tetrazolium at concentrations: 0.0%, 0.1%, 0.5%, 1.0%; (II) moisture content and thousand-seed weight; (III) in-lab germination; and (IV) the classification of seeds’ viability through the use of a seed blower. Meanwhile, seedling production was tested: (I) five compositions of substrates and (II) doses of a controlled-release fertilizer (14-14-14): 0.0, 2.0, 4.0, 6.0, 8.0 g L−1, for S. giganteum. The seed evaluations revealed no significant effect of tetrazolium concentrations on determining their viability. The water content results classify all species as orthodox. All species’ seeds were classified as small according to the weight of a thousand seeds. A maximum of 41% germination was observed for both S. sempervirens and S. giganteum, this value was 56% for P. menziesii, attributed to non-viability and emptiness. The seed blower increased germination by more than 20% for S. giganteum and almost 40% for P. menziesii. Seedling production was affected by the substrates, and a dosage of 4.0 g L−1 of the controlled-release fertilizer is recommended for S. giganteum.