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Selection of superior genotypes of cashew (Anacardiun occidentale l.



Selection of superior genotypes of cashew in Guinea-Bissau 

A project entitled "Selection of superior genotypes of cashew 
(Anacardiun occidentale l.) in Guinea-Bissau and development of in 
vitro techniques for their propagation", lead by Dr. Raul Sardinha 
and Ana Bessa of the Institute de Investigação Científica Tropical, 
Portugal in partnership with other scientific institutions in 
United Kingdom, Portugal and Guinea-Bissau, was carried out under 
the European Union (D.G.XII) STD2 scientific programme.
The cashew is now the main export cash crop for Guinea-Bissau (GB), 
reaching an annual value of about 30 000 ton (1992). The commercial 
value of the nuts is a quality related characteristic: size, 
configuration, density and sanitarian status that may taint 
characteristic taste. In GB the tree is currently being extensively 
planted by seed without proper selection of propagation material. 
Being a free pollinated species and in the absence of seed orchards 
or clonal plantations for seed production there is no guaranty  on 
the value of future crops. This prompted the project aims which 
were developed according to three main areas: screening and 
selecting cashew trees for their technological characteristics; 
study in vitro techniques for clonal tree propagation; and setting 
up a clonal tree bank in GB for further breeding and propagation 
work.
Tree screening along the characteristics of cashew apple allowed 
grouping of trees in seven strata with different cash crop value 
(Table 1). 

Table 1 - Tree's grouping identification
                               
Tree's	Pseudo-fruit					Size	
Type of 
grouping	Form	Color	Size	Astringency	Consistency	
of the nut	Branching
A	Cordiform ("cajú da terra")	Red	Medium	Low to 
medium	Low	Medium	Predom. Intensive to Intensive
B	Periform (caju de Moçambique)	Predom.Red	Medium	
High	High	Big	Mixed
C	Cordiform	Yellow	Big	Low		Medium 
toHigh	Predom. Extensive to Extensive
D	Cordiform	Predom.Yellow	Small	Low to Medium	Low	
Small	Mixed
E	Periform	Red	Medium to Big			
Medium to  Big	Mixed
F	Periform	Yellow	Big	High	High	Big	
Extensive
G	Cordiform	Predom.Red	Medium to  Big	High to 
Medium  		Medium to Big	Mixed
(Predom. = Predominantement)

Considering that under the current market system farmers are paid 
according nut's weight it is shown that attention to seed quality 
and potential is very rewarding. Variation betewen the average 
lighter nut group (4.0 g) and the heaviest (8.7 g) ammounted to 4.7 
g. 

Contract number TS2-A-167

Since yield potential and adaptability to sites prone to "hamatan" 
winds are critical phenological studies were carried out. They 
showed  that flower boson, peak flowering and precociness are 
different for almost all groups which reflects their different 
ecological adaptability and crop potential that must be considered 
in plantation development strategies. 

In this project Dr. Sardinha and collaborators have shown the 
potential of in vitro propagation methods. They have analyzed the 
best explant material to be used. For node culture better media 
combination and parameters for shoot production and root 
differentiation were studied. Although cashew is considered a 
difficult transferring plant, weaning results reached about 83%. 

Considering high running cost of tissue-culture laboratories in 
tropical countries, the project team showed the potential use of 
cuttings under fog conditions (56.8% success). By its simplicity 
and relative low costs of the infra-structures needed, results are 
clearly promising.

Overall, data so far produced created the basis for a breeding 
programme of cashew in GB and open the perspective for quick 
multiplication procedures for selected plant cashew production to 
improve crop yield of guinean and tropical farmers  as well.

Within this project several publications have been issued.

For further information please contact 
Raul Sardinha 
Rua da Junqueira, 86
1300 Lisboa Portugal
Tel  +351 1 364 50 71
Fax: + 351 1 364 20 08
Fax: + 351 1 3973163 
Email rosefn@individual.puug.pt, or 
Ana Bessa
Fax: +351 1 4423023.


Contract number TS2-A-167