上海地区蔬菜生产复种指数高,茬口安排紧,小环棚早熟番茄的定植期通常在3月中、下旬。菜农为早熟番茄提早上市,希望能提早定植。但3月份正处于冬春交替时节,气温年际变化大。若定植早,遇低温年份,易形成僵苗或受冻害;若定植迟,不能充分利用早春的热量资源,成熟晚,影响后茬蔬菜安排。因此进行适宜定植期的试验研 Vegetable production in Shanghai Multivariate index high, crop arrangement tight, small tent shed early tomato planting usually in mid-March, late. Vegetable farmers early listing of early tomatoes, hoping to early colonization. However, March is in the winter and spring alternating season, the temperature varies widely. If planting early, in case of low temperature, easy to form stiff seedlings or frost damage; if late planting, can not make full use of early spring heat resources, mature later, affecting the arrangement of crop vegetables. Therefore, suitable for planting period of experimental research