Production Potentials of Quality Tree Seeds from Orchards and Plantations in Tanzania

The availability of large quantities and high-quality planting materials is essential for the sustainability of tree planting and quality forest products. Since 1950, many countries in Africa have established several seed sources of genetically improved tree species. However, there is insufficient information on production potential, both in terms of quality and quantity of tree seeds from the established orchards and plantations, particularly in Tanzania. We assessed and compared seed production potential and germination capacity of four young (8–14 years) and mature (15–48 years) stands of plantations and seed orchards of Tectona grandis and Pinus patula located in different agro-climatic areas of Tanzania. Each seed source, 16 plots measuring 100 m 100 m, were randomly selected. Each plot, seeds were collected from 30 trees bearing seeds and possessing good characteristics. Results showed that matured stands of T. grandis and patula produced significantly heavier seeds with yields of 51.4 kg ha-1 and 926.1 kg ha-1, respectively, compared to young stands, which produced 28.3 kg ha-1 and 782.6 kg ha-1, respectively. The weight of seeds in orchards was significantly lighter (17.2 kg ha-1) than in plantations (62.5 kg ha-1) for P. patola. In contrast, for T. grandis, the weight of seeds in orchards was heavier (911.8 kg ha-1) than in plantations (796.9 kg ha-1). Seeds from P. patula and T. grandis orchards had significantly higher quality, with germination capacities of 64.5% and 25%, respectively, compared to seeds from plantations, with germination capacities of 51% and 23.2%, respectively. Trees in seed orchards perform better than those in plantations due to superior genetics, controlled breeding, optimal spacing, intensive management, and optimized growing conditions. Germination capacity of P. patula and T. grandis seeds collected from young seed orchards and plantation seed sources was significantly higher than that of mature seed orchards and plantation seed sources.