1主要制约因素1.1自然条件一是生产上对作物类型及品种的要求较为复杂,往往同一村庄或同一农户都要选择几种作物,同一作物又需要选择若干个品种,为生物的多样性提供了良好的生态环境,但却给从事农技推广的农业部门带来了巨大的困难和麻烦。就全市而言,某一作物同一个品种能够推 1 The main constraints 1.1 Natural conditions First, the production of crop types and varieties of the more complex requirements, often the same village or the same farmer have to choose several crops, the same crop and need to select a number of species, provide biological diversity A good ecological environment, but it has brought tremendous difficulties and troubles to the agricultural sector engaged in agricultural extension. As far as the city is concerned, the same species of a certain crop can push