Agriculture Reference
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need to be understood. Regarding growth, preliminary results from an 8-year-
old provenance trial established in Gonsé, Burkina Faso, revealed significant
differences among provenances for tree height, collar diameter and transpiration
rates (J. Bayala, unpublished results). Further observations are expected on fruit
production.
Ber ( Ziziphus mauritiana )
Pareek (2001) has reported high genetic variability in the growth and
morphological characteristics of ber in India, and Diallo (2002) confirmed this in
Africa. Early results from provenance trials in Mali and Senegal indicated
significant differences in growth and biomass production among provenances.
Fruit production was just beginning, but early results suggested that it also varies
among provenances.
Improved cultivars are being produced from China, India and Thailand.
Cultivars such as Gola, Kaithli, Umran and Seb (from India) and Sotubata
(from Thailand) and various sweet Thais (from Thailand) are being tested in
the Sahel, along with the best accessions collected in Brazil, Burkina Faso,
Kenya, Mali, Niger and Senegal. In Burkina Faso, Ouedraogo et al . (2006)
investigated the effects of irrigation, rock phosphate and cultivars (Gola, Seb,
Umran and local as control) on growth and fruit production. At 18 months, the
introduced cultivars performed better than the local cultivar.
10.3.2 Genetic improvement of preferred fruit trees
Genetic improvement using selected clones has been initiated in the Sahel. The
selection of plus-trees and their clonal development may be faster means of
improvement and have greater impact than conventional breeding. However,
considering the trade-off between genetic gain and diversity, it is very important
to ensure that genetic diversity is not severely reduced in the clonal breeding
populations (Cornelius et al ., 2006). This is particularly important for on-farm
breeding populations, because farmers tend to select very few trees/clones to
establish fruit tree populations on the farm (Brodie et al ., 1997; Lengkeek, 2003).
Some plus-trees of Tamarindus indica , Vitellaria paradoxa and Ziziphus
mauritiana were selected by farmers and researchers in 2004-2005, and clones
were established in gene banks and regeneration plots. The initial collections
(more than 150 plus-trees) were made in parts of Burkina Faso, Mali, Niger and
Senegal for all three species, and also in the Tharaka district of Kenya for T.
indica . More collections are planned in the future to ensure that the breeding
population has a broad genetic base. The selected materials will be used for
further improvement programmes and for the production of vegetative plant
materials for large-scale propagation with collaborating farming communities.
Different ideotypes and selection criteria for the species were identified in a
participatory manner with farmers and researchers. The following selection
criteria were retained for the different fruit tree species:
A. digitata : leaf production during dry season, fruit pulp with higher vitamin
C content, high fibre production (Sidibé and Williams, 2002).
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