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山东省费县是近年来板栗生产发展较快的县,年总产量1979年仅19万公斤,1980年增加到60万公斤,1986年又突破了100万公斤,总产量7年增长了4.3倍。 在增产的诸因素中,良种的引进与推广是主要因素之一。1972年起费县先后引进了近20个品种。在进行小区对比试验的基础上,1980年在全县?
Feixian County, Shandong Province, has witnessed a rapid development of chestnut production in recent years. Its annual output was only 190,000 kg in 1979, 600,000 kg in 1980 and 1 million kg in 1986, and the total output increased by 4.3 times in the past seven years . Among the factors that increase production, the introduction and promotion of improved varieties is one of the major factors. Since 1972, Fei County has introduced nearly 20 varieties. On the basis of community comparative test, in 1980 in the county?