Annona Species Monograph.pdf - Crops for the Future

Chapter 13. Conclusions
b) Better methods and enhanced attention to methods of characterizing
germplasm are needed. This also depends on implementing the basic research
in the above point.
c) Accessions in germplasm collections are by no means representative of the
patterns of variation in wild and cultivated species. The current collections
need urgent assessment and they should be nationalized and enriched. The
collections are limited to a few Annona species (especially cherimoya and
soursop) and to a few countries.
d) Variability in seedling rootstock performance, due to genetic diversity, is a
major cause of low scion yield and poor fruit quality. Therefore, research on
selection of vigorous and genetically stable rootstocks is very important.
e) Development of new scion cultivars, and crosses with cultivars with
superior agronomic and yield traits is essential to provide high quality fruits
(among other selected traits, cultivars should have high natural fruit set, out
of season harvest, fruits with symmetrical form, excellent taste and a hard,
resistant rind to improve pest and disease resistance, as well as to prolong
post-harvest life).
f) During selection and breeding there are opportunities to find fruits with
odd characteristics that might attract consumers and better prices. Skin colour
is the obvious trait of interest, but others may exist.
g) For specific pharmacological purposes, evaluation and selection of wild
and cultivated species with important medicinal and insecticidal uses should
be pursued, and supported by field surveys and laboratory analysis
(Abubakar and Abdurahman, 1998; Farrera Villanueva et al., 1999).
h) Biotechnology needs to be much more widely applied. Studies, such as
those of Encina et al. (1999) on genetic transformation to improve the control
of the ripening, to change the post-harvest characteristics of fruits, and to
provide pest and disease resistance should continue.
13.1.2 Propagation studies
a) Vegetative propagation by budding or grafting is slow, often costly and in
some cases, inefficient. Tissue culture research should be accelerated to
provide reliable micro-propagation of desirable planting materials.
153