Agriculture Reference
In-Depth Information
needs to be distinguished from that due to genetic selection. However, limited
research has been undertaken on tree management for indigenous fruit trees
and this gap is noted throughout the present volume. Tchoundjeu
et al.
(2006;
Chapter 9, this volume) described the cultivation of grafted
Dacryodes edules
and
Irvingia gabonensis
on farmers' fields. Similarly, Akinnifesi
et al.
(2006a;
Chapter 8, this volume) also documented the cultivation and management of
planted indigenous fruit trees, including
U. kirkiana
,
S. birrea
,
Z. mauritiana
and
V. infausta
, by farmers in southern Africa. The effect of thinning through
the respacing of natural stands of
U. kirkiana
affected fruit yield parameters
(Mwamba, 1995). Thinning increased fruit load significantly in the first few
years following treatment, and also increased pulp content per fruit. However,
fruit colour and other hereditary traits were unaffected. Such results call for an
investigation into the optimum spacing for these new crops.
Combining the application of fertilizers with irrigation (fertigation) is one
way to achieve improved crop yield and quality in most horticultural tree crops,
e.g. mango. This will ensure that the adverse effects of nutritional deficiencies
on leaf metabolism and growth are overcome (Tomlinson, 1998). Correct
scheduling of irrigation and fertilizer application can help synchronize the
nutrient supply necessary for phenological development. In acidic soils, liming
has also been shown to be important for tree crops (Tomlinson and Smith,
1998). In managing peach palm (
Bactris gasipaes
) in Peru, application of NPK
fertilizer, weeding and timely elimination of excess shoots were found to have
ensured satisfactory performance (Cornelius
et al.
, 2006).
It is often assumed that the establishment and tending of indigenous fruit
trees is generally not different from that of the exotics. However, a recent study
in Malawi comparing the management requirements of
U. kirkiana
,
S. birrea
and
V. infausta
with mango has shown that the cultivation of miombo fruit trees
may not be exactly the same as conventional tree crops (F.K. Akinnifesi
et al.
,
unpublished). Mateke (2003) showed that application of fertigation had varied
effects on
V. infausta
,
S. birrea
and
S. cocculoides
. Fertilizer application,
manure and irrigation did not increase growth and survival in
U. kirkiana
and
S. birrea
, contrary to the widely held assumption that indigenous fruit trees can
be managed as cultivated tree crops. Single factors rather than their
combination may be more important at strategic periods, e.g. a light irrigation
during a period of prolonged drought or dry season. The poor response of
these indigenous fruit trees to fertilizer could be attributed to their adaptation to
infertile soils and unimodal rainfall regimes in their natural stands. However,
this cannot be generalized for all species and locations. Specific management
requirements may be necessary when introducing IFTs into a new area. In
some cases, micronutrients might be more important than macronutrients. This
suggests that research is needed in order to understand and develop
management packages for different IFTs.
In the floodplains of the Peruvian Amazon, the cultivation of camu camu
(
Myrciaria dubia
) was promoted by the government to increase its commercial
production for international and regional markets (Penn, 2006). Farmer
experimentation showed that success was linked to the fact that farmers
combined extension protocols with their own local agricultural practices (Penn,
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