Many countries lacking isolated and vector-free growing
areas that permit the production of quality potato seed tubers
consider microtuber technology a vital component of seed
potato production. These countries include Taiwan (Wang and
Hu 1982), South Korea (Joung et al. 1994), Italy (Ranalli et al.
1994b), the Philippines (Rasco et al. 1995), South Africa (Venter
and Steyn 1997), and many others. In other countries, microtu-
bers are one of several propagules favored during early certifi-
cation stages for seed tuber production. This is true in Europe,
North America. and several South American countries, with
then" long-established certification programs. Microtubers may
also provide a solution in countries where the availability of
high-quality seed tubers forms a constraint due to explosive
increases in new potato growing areas, such as China, India.
and other parts of Asia (FAt 1995; Maldonado et al. 1998).
Microtubers are utilized for minituber (small tubers pro-
duced from in-vitro-produced propagules) production in
greenhouses or screenhouses and, less commonly, are directly
field-planted. Wherever microtuber and minituber production
technologies have been implemented, they have halved the