自古北方种桔必死,或只能为枳,其原因大致有二,其一,柑桔树是由其生命因子与南方特定生态因子长期对应演化而定型的,故而柑桔树只是适应于南方高温高湿的树种;其二,柑桔的成熟期较长,其糖分等营养物质的积累极需较长期高温高湿的代谢环境,它不象葡萄之类的水果需在昼夜温差较大 There are two reasons why citrus trees are dead from the north, or citrus aurantium. First, citrus trees are shaped by the long-term evolution of their life factors and specific ecological factors in the South. Citrus trees are only suitable for high temperatures in the south High humidity tree species; Second, the citrus mature longer, the sugar content of nutrients requires more long-term high temperature and humidity of the metabolic environment, it is not like grapes and other fruits need to have a larger temperature difference between day and night