transformation. Tissue culture offers the opportunity
of producing large numbers of disease-free sweet
potato seedlings. Virus-indexing, usually done before
the tissue culture process, is efficient in virus
detection hence assuring one that the explants being
used are virus-free.
Tissue culture is however, an expensive venture
which has slowed down its adoption in the developing
countries. To ensure the trickling down of TC benefits
to smallholder farmers, low cost tissue culture
interventions are needed. There is a need for low-cost
plant tissue culture systems, applicable for
micropropagation and in vitro conservation of plant
genetic resources in order to increase adoption of TC
in developing countries [3]. Micropropagation costs
include those for nutrient media chemicals. Low cost
tissue culture protocols have been developed for other
crops and have proven to be efficient. Cost reductions
of up to 73% have been recorded for plant
regeneration and in vitro conservation of turmeric [4].
Tremendous work has also been achieved in reduction
of cassava micropropagation costs [5].
However, despite all the efforts that have been
made in lowering the costs of tissue culture,
genotype-dependent response to various TC media
remains an impediment. Genotype-dependent
morphogenetic response has been reported in pigeon
pea [6]. Genotype-dependent effects imply that tissue
culture and transformation strategies must be
re-designed for poorly performing genotypes and
different protocols developed for different genotypes.
This study sought to monitor the response of two
sweet potato varieties, KEMB 36 and Tainurey, to a
low cost tissue culture medium.
2. Materials and Methods
2.1 Plant Materials
Vines of two sweet potato varieties, KEMB 36 and
Tainurey, obtained from the Kenya Agricultural
Research Institute on the basis of farmer-preference
were used in this research.
2.2 Media Preparation
A low cost medium where locally available
fertilizers were used as alternative nutrient sources
was developed (Table 1). The conventional source of
all the macronutrients apart from calcium chloride was
substituted with locally available fertilizers. A single
substitution was done for the case of the source of
micronutrients. Stanes® Iodized Microfood that
contains microelements required for plant growth was
used as the alternative source for the micronutrients.
Table sugar obtained from local shops was used as the
Table 1 Composition of the low cost medium used in sweet potato tissue culture.
Component
Amount in stock solution
(g/L)
Amount in culture
medium (g/L)
Amount of stock solution per
litre of the medium (mL/L)
Macronutrients
Calcium chloride (conventional) 9 0.9
100
Monopotassium phosphate (MKP) 3.5 0.35
Potassium nitrate fertilizer 40 4
Ammonium nitrate (quarry explosive) 35 3.5
Magnesium sulphate
Epsom salt 37 0.37 10
Micronutrients
Stanes® Iodized Microfood - 0.2
α
-
Carbon source
Table sugar - 30
α
-