Effects of Provenance and Seed Size on Germination, Seedling Growth and Physiological Traits of Gmelina arborea, Roxb

摘要

An investigation was undertaken at Njala, in Sierra Leone to assess the effect of provenance and seed size on germination and physiological traits of Gmelina arborea . The objective of the study is to identify seed size and sources that are superior in terms of important characteristics that would be the best sources for seed improvement programmes and production of Gmelina trees. Seeds of Gmelina were collected in 2014 from four geographically distinct provenances in Sierra Leone. The experiment was 4 x 3 factorial laid in a randomized complete block design with four replications four levels of provenance (seed origins), North, South, East and West and three levels of seed sizes – Small, Medium, and Large. The results showed that both germination percentage and germination rate of Gmelina were significantly affected by seed size. The large and medium seed sizes from different provenances had significantly higher germination percent and germination rate than the small seed size. Highly significant (P < 0.001) differences were observed in germination percentages among the different seed sizes at 2 and 3 weeks after planting (WAP). The large seed size which had the highest germination percentage at 2 WAP (66.4%) and 3 WAP (78.1%) followed by the medium size seeds at both 2 WAP and 3 WAP (61.4% and 74% respectively). Results of the correlation analysis showed a strong positive correlation (r = 0.91) between seedling height and total biomass. Similarly, a positive correlation was observed between shoot dry weight and total biomass (r = 0.72) while as the correlation of root dry weight and total biomass was very weak (r = 0.45). Provenance significantly affected shoot dry weight and total biomass of Gmelina seedlings. Seedlings from seeds obtained from the East and Southern regions consistently had higher shoot dry weight and total biomass than seeds obtained from the North and Western regions.It can be concluded that seed size is a major parameter for predicting germinabilty and seedling establishment of Gmelina . The best seed sizes to use by tree planters and other stakeholders were the large sized seeds because of their fast germination and seeds from the east and south will promote early maturity of Gmelina arborea for purposes such as pulp paper production, timber and fuel wood.