INFLUENCE OF DIFFERENT LIGHT INTENSITIES ON THE GERMINATION AND EARLY GROWTH OF Treculiaafricana

INFLUENCE OF DIFFERENT LIGHT INTENSITIES ON THE GERMINATION AND EARLY GROWTH OF Treculiaafricana

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               CHAPTER ONE

1.0  INTRODUCTION

1.1 GENERAL



Non-timber forest products (NTFPs) are wild plant and animal products harvested from forests,

such as wild fruits, vegetables, nuts, edible roots, honey, palm leaves, medicinal plants, poisons

and bush meat. They are all non-timber resources that are extractable from forests, which have

economic, cultural and social values and are utilisable in households (FAO, 1990). NTFPs add to

peoples’  livelihood  security,  especially  the  rural  dwellers  who  depend  on  them. Non-timber

forest products (NTFP) are also considered as any commodity obtained from the forest that does

not  necessitate harvesting  trees.  It  includes game  animals, fur-bearers, nuts and seeds, berries,

mushrooms, oils, foliage, medicinal  plants, peat, fuelwood, forage,  etc  (Emery et  al, 2001).

Millions of people – especially those living in rural areas in developing countries – collect these

products daily, and many regard selling them as a means of earning a living (Tinde van Andel,

2006).



Non-timber forest products (NTFPs) were long considered as minor forest resources. Economic

studies  of  forest  management  generally  ignored the  subsistence  these  resources  provide  local

populations.  Only recently has NTFPs attracted  the  attention  of  researchers,  particularly  those

concerned  with  tropical  forests  (Lescuyer,  1996). These  studies  have confirmed  that the forest

ecosystem generates other resources which also have economic values apart from the well know

timber that are popularly harvested (Karsenty and Maîtres, 1995).

For centuries, humans around the world have relied on products derived from forest species for

their survival and well-being. NTFPs harvesting and utilisation remains widespread throughout

the  world.  People  from  diverse  income  levels,  age  groups,  and  cultural  backgrounds  harvest

NTFPs for household subsistence, maintaining cultural and family traditions, obtaining spiritual

fulfilment,  maintaining  physical  and  emotional  well-being,  scientific  learning,  and  earning

income.  NTFPs  serve  as  raw  materials  for  industries  ranging  from  large-scale  floral  greens

suppliers  and  pharmaceutical  companies  to  micro-enterprises  centered  around  basket-making,

woodcarving,  medicinal  plant  harvesting  and  processing,  and  a  variety  of  other  activities.

Estimating  the  contribution  of  NTFPs  to  national  or  regional  economies  is  difficult  due  to  the

lack  of  broad-based  systems  for  tracking  the  combined  value  of  the  hundreds  of  products  that

make up the various NTFP industries.



In tropical forests, NTFPs can be an important source of income that can supplement farming or

other  activities.  A  value  analysis  of  Amazonian  rainforest  in  Peru  found  that  exploitation  of

NTFPs could actually yield higher net revenues per hectare than timber harvest of the same area,

while  still  conserving  vital  ecological  services. Their  economic,  cultural,  and  ecological  value

when  considered  in  aggregate  makes  managing  for  NTFPs  an  important  component  of

sustainable forest management and the conservation of biological and cultural diversity (Encarta,

2011).



Treculiaafricana (African breadfruit, African boxwood or Wild jackfruit) belongs to the mono

specific genus TreculiaDecne. Ex Trec which is one of the fifteen genera of plants belonging to

the  tribeArtocarpeae  in  the  Mulberry  family  (Moraceae) (Keay,  1989).  This  species  is  largely

                                            13


cultivated  within  the  rainforest  belt  of  West,  Central  and  East  Africa  (Keay,  1989).  It  is an

evergreen  forest  fruit  tree species (Onyekwelu  and  Stimm,  2008). The  plant  produces  large,

usually  round and compound  fruits  covered  with  rough  pointed  outgrowths  (Keay,  1989;

Onyekwelu and Stimm, 2008). 

Treculiaafricanahas  very  large  simple  and  alternate  leaves.  The  leaves,  which  are  about  30

(max. 50) x 14 (max 20) cm in dimension, are dark green in colour. The leaves are smooth above

with  tough,  paler  below  with  some  hiars  on  the  10-18  pairs  of  clear  veins  with  a  pointed  tip

(Rohwer, 1993; Orwa et al 2009). Treculiaafricana has compound, rounded, very large fruits,

on the trunk or main branches, containing many orange seeds, about 1 cm, buried in spongy pulp

of the fruit. The outer surface is covered with rough pointed outgrowths. The fruit attains 40 cm

in diameter and weighs 8-14 kg (Orwa et al 2009).



Based  on  detailed  field  observations,  3  varieties  have  been  recognized,  which  are: T.  africana

var. africana, T. africana var. inversa and T. africana var. Mollis
(Chris Chinaka, 1998). Their

taxonomic  differences  are  based  mainly  on  the  size  of  the  fruit  head  (infructence)  and  the

hairiness  of  branchlets  and  leaves.  There  is  a  striking  variation  in  the  number  of  fruit  heads

produced  by  trees  belonging  to  T.  african  var.  africana  (with  large  fruit  heads)  and  T.  African

var.inversa  (with  small  fruit  heads).  The  former  is  clearly  superior  in  the  weight  of  seeds

produced  while  the  latter  produces  more  fruit  and  also  produces  twice  as  many  branches

(Nwokolo, 1987; Omobuwajo et al., 1999; Orwa et al 2009).



Treculiaafricanaand  other  forest  food  plants  like Pentachlethramacrophylla (oil  bean  seed),

Dacryodesedulis are of high nutritional value which needs to be introduced or added to our food

materials consumed (Edet et al., 1985; Nwokolo, 1987). The importance attached to them is due

to the fact  that many of  them are usually  available at  strategic period of  the  year  when annual

crops that are difficult to store are unavailable or scarce (Okafor, 1978).



Despite  the  socio-economic  importance  of Treculiaafricana to  a  very  large  population  of  the

people of southern Nigeria, it is still a protected crop and a semi domesticated species. Increase

in human population and agricultural practices have put pressure on the forest thereby depleting

some  genetic  resources, Treculiaafricana being  a  good  example.  To prevent  total  loss  or

extinction of important forest food tree species, especially those that are endangered, they must

be cultivated more intensely (Baiyeri, 2003; Ugwunze, 2003).



While seed germination and plant growth are regulated internally, they are greatly influenced by

external  conditions  such  as  the  intensity  and  duration  of  light  and  temperature.  Aside  from  its

effect  through  photosynthesis,  light  influences  the  growth  of  individual  organs  or  of the  entire

plant in less direct ways. The most striking effect can be seen between a plant grown in normal

light and the same kind of plant grown in partial darkness or total darkness. The plant grown in

the partial dark or total dark will have a tall and spindling stem. The leaves fail to expand, and

both  leaves and stem, lacking  chlorophyll,  are pale  yellow. Such a plant is  said  to  be etiolated

(Dennis Holley, 2009)

Both  the  intensity  and  duration  (length)  of  light  may  have  different  and  characteristic  effects

upon plant growth and development. It has been found that the length of the daylight period may

have a striking effect upon vegetative growth and reproductive activities of plants. The reaction

of plants in relation to the length of the day is called photoperiodism(Dennis Holley, 2009)

This  study  is  carried  out  to investigate how Treculiaafricanaseeds  and  seedlings respond  to

various  light  intensities  and to  also  monitor  the  early  growth  characteristics  and  habits  of  the

seedlings of the species  under three different  light  intensities using three screen houses, which

are compared with the performance of seeds and seedlings of the species sown and planted under

open nursery condition as well as under forest canopy. 



1.2  STATEMENT OF PROBLEM

Despite the economic, nutritional, cultural and social importance of Treculiaafricana, especially to

rural dwellers that depend on them, ithas been greatly neglected, especially with respect to their

regeneration. The yield of current crop of trees is decreasing due to old age and the fact that it has

been harvested for decades. Thus, if the current practice of allowing T. africana to grow in the wild

is allowed to continue without deliberate silvicultural interventions, the probability of obtaining its

valued products on a sustained basis will be very low. Due to lack of care and old age, a lot of the trees of the species have died or are in the process of doing so, thus the species is classified among

the  endangered  tree  species  in  Nigeria  (FORMECU,  1999),  with a  high  possibility  of  going  into

extinction  in  the  near  future  except  something  is  done  to  increase  its  population.  Allowing  the

species to go into extinction will endanger the livelihood of millions of rural dwellers in Nigeria and

reduce  the  rich  biological  diversity  of  the  ecosystem.  Artificial  regeneration  and  subsequent

improvement  (domestication)  appears  to  be  a  very  viable  option  of  saving  the  species  from

extinction  and  ensuring  that  its  products  are  supplied  on  sustained  basis. The  need  to  rapidly

domesticate tropical forest food tree species has been stressed and is now one of the three pillars

of  the  International  Centre  for  Agroforestry  Research  (ICRAF)  program  (Leakey  and  Simons,

1998). 

Seed  germination  and  early  growth  of  forest  seedlings  is affected  by  some  factors  such  as  light

intensity, air, temperature, water, soil condition, etc. Except these factors or their combinations are

provided at the right time and in good quantity, seed germination and growth of seedlings may be

adversely affected. Till date, research work on the effect of light intensity of the germination of T.

africana
seeds and the early growth of its seedlings is scanty, which is the focus of this study. 



1.3  OBJECTIVES

The general objective of this study is to investigate the effect of different light intensities on seed

germination and early growth rate of Treculiaafricanaseedlings.

The specific objectives are:

      a.To investigate the germination potential of Treculiaafricana seeds under different

          light intensities.

      b.To assess the influence of light intensity on survival and early growth performance

          of Treculiaafricanaseedlings.



1.4 JUSTIFICATION

Research  on  domestication  of  forest  food  tree  species  is  still  at  a  preliminary  stage.  Specifically,

efforts  on  domestication  of T.  africana only  covers  seed  storage  and  germination,  vegetative

propagation, germplasm  collection,  priority  setting  exercise,  integration  into  agroforestry,

economic and nutritional importance, selection of multiple traits for potential cultivars, (Okafor,

1991; Leakey  and  Simons,  1998; Enibe,  2003; Leakey et  al.,  2003;  Kumar  and  Nair,  2004;

Onyekwelu  and  Fayose,  2007;  Onyekwelu  and  Stimm,  2008).  Till  date  no  known  work  on  the

effect  of  different  light  intensities  on  seed  germination  and  early  growth  rate  of T.  africana

seedlings  has been  carried  out,  though  it  has  been  established  that  light  intensity  affects  seed

dormancy  breakage,  seed  germination,  early  growth  performance,  etc  of  seedlings.  This

underscores the need for a study that will investigate the effect of various light intensities on the

germination and early growth rate of T. africanaseedlings, which is the focus of this study. It is

believed that this will aid the selection of the most appropriate light intensity that will facilitate

the highest and regular seed germination as well as the fastest growth rate. In this study, nursery

experiment with the seeds of T. africana will then be conducted to investigate the germination

and  early  growth  characteristics  of  the  seedlings  of  the  species  under  three  different  light

intensities using three screen houses. 



1.5 SCOPE OF STUDY


The research work was carried out at the nursery site of the Department of Forestry and Wood

Technology,  Federal  University  of  Technology  Akure,  Nigeria. Treculiaafricana fruit was

obtained from Forestry Research Institute of Nigeria from which the seeds were extracted. Four

hundred (400) seeds of Treculiaafricanaweres sown in each of the three screen houses which

allows  40%,  60%  and  100%  light  intensities. Also, 400  seeds  were sown in  open  nursery

condition (i.e. outside the screen house) as well as under forest canopy, which served as controls

1  &  2, respectively. Seed  germination as  well  as  early  growth characteristics of  the  seedlings,

such  as  survival,  collar  diameter,  height,  root  length,  number  of  leaves  and  biomass. were

monitored for Eighteen weeks.





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