Agriculture Reference
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squamosa , because they were the highest-ranking species in Ghana, and Coula
edulis , Tetrapleura tetraptera and Spondias mombin , because they were
believed to be important across the region, even though they did not rank
particularly high in the farmer preference survey.
Screening on basis of researchability
D. edulis and I. gabonensis rated highest on researchability in the survey of
researchers (Table 1.3), as they did in the farmer preference survey. Both
species are known to have a high level of genetic variability, and the knowledge
base concerning them is high relative to the other species. Both have short
reproduction cycles; they can each bear fruit within 5 years ( I. gabonensis only
through vegetative propagation). C. albidum ranked fifth, receiving low to
medium ratings on germplasm availability, knowledge base, and the level of
Table 1.3. Weights of criteria on researchability and mean scores of tree species on criteria.
Level of
Uniqueness
genetic
Knowledge
Germplasm
Speed of
of research
Total
Ordinal
Criteria
variability a
base b
availability c
reproduction d
efforts e
score f
score
Weight g
3
2
2
2
1
Mean scores h
Dacryodes edulis
3.0
2.0 1
2.2 1
3.0
2.3
25.7
High
Irvingia gabonensis
2.8
1.7 1
2.0 1
3.0
2.7
24.5
High
Spondias mombin
2.3
1.25
1.7 1
3.0
3.0
21.8
Medium
Tetrapleura tetraptera
2.4
1.25
1.7 1
2.0
3.0
20.1
Medium
Chrysophyllum albidum
2.0
1.25
1.0 1
3.0
3.0
19.5
Medium
Artocarpus communis
1.5
1.3 1
1.0 1
3.0
3.0
18.1
Medium
Coula edulis
2.5
1.25
1.5 1
1.0
3.0
18.0
Medium
Annona squamosa
1.0
1.0 1
1.0 1
3.0
3.0
16.0
Low
Garcinia kola
1.5
1.3 1
1.6 1
1.0
3.0
15.3
Low
Ricinodendron heudelotii
1.0
1.4 1
1.25
2.0
2.8
15.1
Low
a Includes number of provenances, phenotypes and differences in fruit size, quality and
growth rates.
b Includes all information available on the species, including knowledge about sexuality,
flowering/fruiting habits, pests and diseases. Indicators include number of publications and
number of researchers working on it.
c Indicates whether collections have taken place, numbers of accessions in gene banks, ease
of collection, fruiting frequency, and storeability of seed.
d 0-5 years = 3, 6-10 years = 2, 11+ years = 1. Through vegetative or other methods of
propagation.
e Considers whether other research groups are already working on the domestication of the
species and whether there is a risk of duplication of effort.
f Each criterion score is multiplied by the weight of the criterion to arrive at a weighted
criterion score.
g As determined by the priority-setting team.
h 3 = high, 2 = medium, 1 = low. Twelve researchers rated the species but not all rated each
species on each criterion.
 
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