Assessment of the influence of seed source on growth performance and reproduction phenology of Tetrapleura Tetraptera

A dissertation submitted to the Directorate of Research and Graduate Training in partial fulfilment for the award of Master of Science in Forestry and Biodiversity Management of Makerere University.

The decline of tropical forest areas and the potential extinction of valuable indigenous tree species like Tetrapleura tetraptera pose significant threats to biodiversity, carbon stock, and ecosystem services. This study addressed the lack of phenological knowledge about T. tetraptera, aiming to understand its growth performance, flowering and fruiting patterns, and the influence of seed source, for informed on-farm cultivation and conservation strategies. The study identified optimal ecological zones for understanding growth, flowering, and fruiting of T. tetraptera to support its cultivation. The specific objectives were to assess temporal patterns of flowering and fruiting; investigate the impact of seed source on growth performance; and determine the impact of seed source on flowering and fruiting of the species. The study was conducted in Kifu Forest Reserve in Mukono District, Central Uganda. The experiment was established with provenance plots of T.tetraptera from six ecological zones in a randomized complete block design with three replicates and 33 accessions per block. Data collection involved inventorying trees and assessing parameters, categorized into height growth, flowering and fruiting events. Data were analyzed using linear mixed-effect models in R version 4.3.0 for Windows. T. tetraptera showed a unique flowering pattern with two distinct peaks in April to June and October to December, both had the highest number of flowers, while the fruiting pattern was characterized by a major peak from June to December and a minor peak in January and February, with minimal fruiting in April. The seed source significantly influenced the growth performance with the moist evergreen and transition zones exhibiting the highest mean height, while the derived savannah showed the lowest mean height. The number of flowers in T. tetraptera varied across different ecological zones, with the moist evergreen zone having the highest mean number of flowers, while the transition zone had the lowest. Across all zones, sub-mature flowers were higher than young and mature flowers implying that T. tetraptera spends longer in the sub-mature flowering stage. The number of fruits varied across different ecological zones, with the transition zone, semi-deciduous, and moist evergreen zones having the highest mean number of fruits, while the derived savannah had the lowest. T. tetraptera from the semi-deciduous zone of Ghana produced more flowers and fruits and had greater mean height than that of Uganda.