营造农田防护林体系是提高农作物产量与质量的有效手段之一。国内外已有不少关于林带使作物增产的报道;法国人Guyot指出,灌溉条件下,林带可使小麦增产21.8％,丹麦人研究认为,可以平均增产5％,据我们1985年研究认为,在100亩左右的长方形林网内平均增产5.5％。有关林网保护下的农作物质量及其增产机制的报导还不多见。为了系统的了解防护林体系保护下的农作物产 The establishment of farmland shelterbelt system is one of the effective means to improve crop yield and quality. There have been many reports at home and abroad about crop yield increase in the forest belt. According to the French Guyot, under irrigation, the yield of wheat increased by 21.8% in the forest belt. According to the Dane study, an average increase of 5% could be achieved. According to our 1985 study, About 100 acres of rectangular forest net yield 5.5%. Reports on the quality of crops under crop protection and their mechanisms for increasing yields are rare. In order to systematically understand the crop protection under the protection of the forest system