Closed Systems For High Quality Transplants Using Minimum Resources

Abstract

Micropropagation is a method to propagate plants vegetatively under aseptic conditions in a culture vessel mostly under artificial light to produce a number of disease-free transplants. “Photoautotrophic” micropropagation is a method of micropropagation to grow plants photosynthetically under aseptic conditions on the sugar-free culture medium using leafy or chlorophyllous explants in a ventilated culture vessel (See also Kozai and Xiao in this book). Photoautotrophic micropropagation differs from conventional vegetative propagation in size of explants (or cuttings) and the degree of asepsis of culture medium and/or plants. In addition, conventional vegetative propagation is conducted mostly under natural light in a greenhouse or a nursery. Micropropagated plants in vitro grown on sugar-containing or sugar-free medium are basically aseptic, but conventionally propagated plants using cuttings are not. Strictly speaking, the purpose of micropropagation is not to produce aseptic plants, but to produce pathogen- or disease-free and physiologically healthy plants, which are tolerant to various kinds of environmental stress. Aseptic plants are pathogen free, but pathogen free plants are not necessarily aseptic, because microorganisms are not necessarily pathogens. A closed transplant production system using artificial light described in this chapter is a system for producing disease-free transplants (but not aseptic transplants) at low costs with minimum use of resources. The system can be used both for plantlet and seedling production (Plantlets mean small plants vegetatively propagated and seedlings mean small plants grown from seeds.) In this sense, a closed transplant production system is one type of plant propagation and/or transplant production systems. In the closed transplant production system, however, more attention is paid with respect to resource saving and environmental conservation than in the photoautotrophic micropropagation system. In this chapter, the definition, concept, theoretical backgrounds, methods, materials, applications, and advantages of the closed system for transplant production using lamps over a greenhouse using sunlight are described from biological, engineering and economic points of view.