International Journal of Wood Science, Technology and Forestry (IJWSTF) ISSN: 1725-3497, Vol. 6(1), pp. 111-150, October, 2021.  © Advanced Scholars Journals

Full length Research paper

 Assessing the effects of six organic and inorganic treatments on germination and incremental growth of three tree species

A thesis presented

 in partial fulfilment of the requirements for the award of Doctor of Philosophy (PhD) forestry

Department of Forestry Faculty of Life and Earth Sciences,

Bircham International University

Dr. Gbessay Ehlogima Sam Momoh

Doctor of Philosophy (PhD) forestry

4th June, 2021

"I do hereby attest that I am the sole author of this thesis and that its contents are only the result of the readings and research I have done’’.




 This is to certify that Gbessay Ehlogima Sam Momoh in the Department of Forestry in the Faculty of Life and Earth Sciences of Bircham International University has fulfilled the requirements prescribed by the University for the award of the PhD degree. The thesis titled ‘Assessing the effects of six organic and inorganic treatments on germination and incremental growth of three tree species’ was carried out under my direct supervision. No part of this thesis has been submitted for the award of any diploma or degree prior to this date.

Professor William Martin

Faculty of Life and Earth Sciences

Date:17th June, 2021


The purpose for this two-track research initiative was to substantiate misconceptions about organic and inorganic manure through perception survey and secondly, to test the effects of the six organic and inorganic treatments on the germination and growth of the three tree species. Growth. Three tree species were identified for this research intervention based on the respective functions of these species in revenue generation, relative growth rate, easy availability, climate change mitigation, sinking of carbon emission, meeting social, furniture and construction needs etc. These species include, Terminalia ivorensis, Gmelina aborea and Theobroma cacao. Terminalia ivorensis, a native species in Sierra Leone is hard to germinate. It is good for timber and many people use it for furniture and construction work. It can cure many ailments and diseases. Gmelina aborea is an alien species, regarded by many to be domineering and evasive. Those interviewed considered it to have the tendency of dominating the entire landscape of Sierra Leone in the next 50 years. It has medicinal values. Theobroma cacao was introduced in the South/East of Sierra Leone as a commercial tree crop. The seeds are sold and exported for the production of cholate. Rural people locally pound it in to powder and use it as substitute for tea or coffee. The leafs, roots, stem and bark also have medicinal values. The combination of three different treatments (ordinary soil, sawdust and fertilizer) resulted in six different treatments which were used to achieve the experimental research initiative. For each treatment, 50 viable seeds of each tree species were nursed at the same time. Thus 900 seeds were nursed (50 seeds x 3 tree species x six treatments). The resultant effect of these three treatments gave rise to the following six organic and inorganic treatments:


i)       ordinary soil alone;

ii)       organic manure alone;

iii)       powdery sawdust alone;

iv)      burnt sawdust mixed with ordinary soil;

v)      powdery sawdust mixed with ordinary soil and

vi)      fertilizer mixed with ordinary soil;

The social survey revealed that people’s perception of organic and organic manure has effect on the consumption of products from these treatments. There is the need to address these misconceptions if development in this field is to be enhanced. Germination and incremental growth rate comparison was done at two different levels (within and across species under the six treatments). The research revealed that all the six treatments can support seed germination and expedite seedling growth. Ordinary soil can support plant germination and incremental growth in nurseries if it is fertile. The research proved that powdery sawdust can trigger and expedite seeds germination and incremental seedling growth rate. This was also true for sawdust mixed with other treatments. Yellowish colouration of the leafs were noticed with powdery sawdust alone two weeks after germination but this was not so with sawdust combined with other treatments. Terminalia ivorensis a native species of Sierra Leone took 27 days to germinate. For burnt sawdust mixed with ordinary soil and organic manure alone, it took 18 days to germinate.  For fertilizer mixed with ordinary soil, the seeds germinated within 18 days. However, only few of the seeds germinated. On average, the seeds took 21 days to germinate with a germination rate of 47%. In terms of incremental growth under ordinary soil powdery sawdust and sawdust mixed with ordinary soil. Terminalia ivorensis seedlings under organic manure treatment witnessed the highest increment in height with stem increasing by 7.8mm, the leaf length by 5.1mm and leaf width by 2.3mm within 20 days compared to the rest of the other treatments. Thus, the daily incremental growth rate calculated for Terminalia ivorensis under this treatment was 0.41mm per day. Gmelina aborea under the five treatment manifested positive results in terms of germination and incremental growth rate except fertilizer. On average, it took 8 days for the seeds to germinate under all the treatments at a germination rate of 53%. For the ordinary soil, burnt sawdust, organic manure mixed with ordinary soil, the seeds took 7 days to germinate but for powdery sawdust and sawdust mixed with ordinary soil, the seeds took 10 days to germinate. The highest increment was recorded under ordinary soil treatment as at 9.8mm stem height, 4.5mm leaf length and 4.3mm leaf width. By using the incremental growth rate formula, Gmelina aborea increased by 1.4mm per day. Theobroma cacao, a commercially valuable tree species seeds nursed witnessed mortality after the first date of nursing. This was attributed to poor pre-germination treatment of the seeds (removed from pods, travel long distance and seed not carefully handled). A fresh seeds was collected from communities near the nursery site. On average, the seeds in the six treatments took 11 days to germinate at 52% germination rate. For the ordinary soil, burnt sawdust, organic manure mixed with ordinary soil and sawdust mixed with ordinary soil, the seeds took 11 days to germinate but for powdery sawdust and inorganic (fertilizer), the seeds took 13 days to germinate. The highest increment in stem height of 31.9mm was recorded under powdery sawdust at 31.9mm. The leaf length and width increased by 16.3mm and 6.7mm respectively. The incremental growth rate was calculate to be 0.31mm per day.