1.4 Japan
in japan primitive methods using oil paper and straw mats mats to protect crops from the severe natural environment were used as long ago as the early 1600s. widespread implementation of protected cultivation in japan began in 1951 after the introduction of PVC(polyvinyl Chloride)films, and the benefits of its application to agriculture were quickly appreciated. paper-covered tunnel were rapidly replaced by PVC films-covered ones Traditional wooden or bamboo frames were replaced with steel first and then with aluminum and plastics in some cases. Mulching with plastics began with PVC films, but later shifted to PE (Polyethylene) after its introduction
protected cultivation is one of the promising ways of supplying food under unfavorable environmental conditions in japan if the energy problems can be solved. the past and present situation in japanese protected cultivation is summarized in table 1.4 and fig 1.1 (The data in the figure are only for greenhouses.) this figure shows that rather steady expansion of protected cultivation area has continued for years along with the development of new covering materials, but it is clear that the expansion rate of plastic houses leveled at the time of the steep oil price increases in the 1970s. one of the particular in japan is that the area for pomiculture is now