Factory raising seedlings based on tray raising seedlings technology was imported to China in the 1980s.
The existing patterns of raising seedlings are mainly small raising seedlings greenhouse, intelligent raising
seedlings greenhouse and factory raising seedlings. For small building greenhouse, it covers the too large area,
after seedling period it is dismantled and will not be able to reuse, so the resources are largely consumed. For
intelligent raising seeding greenhouses, it realizes the controlling of temperature, water, light and humidity.
For raising seedlings factory, it mainly adopts the intensive management way in which the water is needed for
germination and growth of seedlings, fertilizer and temperature are controlled automatically. For example,
Xinhua branch of Heilongjiang Beidahuang limited Inc. built a three-dimensional raising seedlings factory
with rotating brackets (Fig. 4.), which covers only 700 square meters with 864 brackets. These brackets work
a cycle per half an hour uniformly and can produce more than 6,000 trays seedlings at a time.