Vegetable production in solar plastic greenhouses: past, present and future in Shandong Province.

摘要

The primitive form of solar plastic greenhouse (SPG) was plastic covered "Yang Qi", which was normally used for culture of vegetable transplants but with glass windows. Since its appearance in Shandong Province (China) around 1989, SPG has gone through major modifications on both structure and cover materials. Most of current SPGs have three solid brick/soil walls (the east, west and north side) and polyethylene plastic covers (the south side and top). Relying exclusively on solar energy, SPG is capable of producing over 30 different vegetable species, including temperate vegetable crops in winter, at regions with the minimal temperature above -15 degrees C. The acreage of SPG in Shandong Province has exceeded 140 kha, producing 20-25% of the vegetables in China. The total output and value of vegetables produced was 18.5% and 20.4% of the nation, respectively. The export of Shandong vegetables was about a million t/year, valued over $400 million. In addition to the improvement in SPG structure, progress in the cultivation techniques through the years had made the rapid growth in SPG acreage possible. These techniques, which had aided in boosting farmer's profits from $15k/ha to $50k/ha, included the use of SPG specific cultivars, grafted transplants, adequate fertilizer, CO2 implementation, and scientific temperature controls. The major challenges to vegetable production in SPGs are soil deterioration and severe plant disease and pest problems. Future study should address the integrated pest control, diversification of vegetable species and cultivars, and improvement of qualities in vegetable produces.