(一)引言珠江三角洲是西江、北江和东江下游的冲积平原,范围涉及27个县市,面积约36700平方公里。珠江三角洲地处亚热带,土地肥沃,年平均气温在20～23℃之间,全年都是无霜期,年雨量一般在1600毫米以上。这些优越的自然条件,都为发展农业生产提供了十分有利的条件。本地区既是重要的商品粮产区,又是糖、丝、水果等重要经济作物产 (A) Introduction The Pearl River Delta is an alluvial plain in the lower reaches of the Xijiang River, Beijiang River and Dongjiang River. It covers 27 counties and cities and covers an area of ​​36,700 square kilometers. The Pearl River Delta is located in the subtropical zone with fertile land. The annual average temperature is between 20 and 23 ℃. The annual frost-free period is more than 1600 mm. These superior natural conditions all provide very favorable conditions for the development of agricultural production. The region is not only an important commodity grain producing area but also an important economic crop such as sugar, silk and fruit