Agriculture Reference
In-Depth Information
species have not yet been fully developed. The quality of products depends on
good-quality planting material, and there is a strong need to carry on
production and processing activities in parallel so that good-quality raw
materials are available for processing and marketing so as to generate income
for household farms.
Recent work on intraspecific variation in indigenous fruits and other AFTPs
has shown that there is three- to sixfold variation in almost every trait
investigated, whether these traits are morphological, physiological and/or
chemical/physio-chemical. A participatory selection of superior germplasm has
been undertaken with diverse users across countries in southern Africa
(Akinnifesi
et al
., 2006), and improved cultivars have been established in fruit
orchards developed by clonal methods. A similar selection for ideotype
candidate trees was also reported in West Africa (Lovett and Haq, 2000). This
offers an opportunity for multi-trait selection and the development of market-
oriented ideotypes through domestication procedures based on the vegetative
propagation of superior trees, and the consequent development of cultivars.
3.2.2 Limitations in production systems
Agroforestry systems developed by researchers, such as alley cropping, have
been found to be limited in terms of adoption by farmers (Sumberg and Okali,
1988). Mixed systems with economic crops have been reported as a viable
alternative to slash-and-burn agriculture (Palm
et al
., 2005). Many of these are
agroforests that include a range of indigenous fruit trees (Kindt
et al
., 2004;
Schroth
et al
., 2004; Degrande
et al
., 2006). There are relatively few fruit-
tree-based farming systems that have been well researched, although the use of
indigenous fruit trees as an income-generating, shade-producing canopy for
cocoa is common in western and central Africa (Leakey and Tchoundjeu, 2001).
However, Hocking
et al
. (1997) reported economic yield depression from their
investigation in Bangladesh when they included trees in rice and wheat
production systems. They reported that there was a variable depression in rice
(
Oryza sativa
) and wheat (
Triticum aestivum
) yields, ranging from 16 to 40%,
when grown under the tree species
Acacia catechu
,
Artocarpus heterophyllus
and
Mangifera indica
. Similar studies are needed in agrosystems where
comparative costs and benefits can be assessed between the loss of crop yields
and the gain in tree products of high value, mainly fruits and fodder. Izac and
Sanchez (2001) compared the relative benefits of high yield in cash crops and
high profitability with high biodiversity in mixed systems. They also reported
that, in order to derive the greatest benefit from mixed systems, greater flexibility
is needed in the selection of crop species than in traditional farming. Gockowski
et al
. (1997), Gockowski and Dury (1999) and Palm
et al
. (2005) have reported
cost benefits from fruit trees and agroforests. However, in all cases there is a
need to consider environmental advantages in a cost-benefit analysis.
Agriculture in the tropical world, with a few exceptions, has suffered from a
lack of mechanisms to introduce, test and understand less important species.
However, when a number of such species were tested, the germplasm base was
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