国外蔬菜育苗很早就采用了较小密度和优良基质来提高秧苗素质。以番茄为例,美国的标准密度是63株/m~2,英国的密度60株/m~2,比200株/m~2定植后早熟5天,前期产量增加50％。一些发达国家无土育苗的基质大都采用泥碳、岩棉、蛭石,无土育苗的番茄比有土育苗秧苗生育期缩短20～30天,素质好,定植后前期产量及总产量高。 Foreign vegetable nursery early use of a smaller density and good substrate to improve seedling quality. Take tomato as an example, the standard density of USA is 63 plants / m ~ 2, the density of UK is 60 plants / m ~ 2, which is 50% more than that of 200 plants / m ~ 2. In some developed countries, soilless seedling substrates mostly use peat carbon, rock wool and vermiculite. Soilless seedlings have a shorter growth period of 20-30 days than soilless seedling seedlings, with good quality and high initial yield and total yield after planting.