大白菜是北京地区秋冬季节的当家菜,在京郊蔬菜生产中占有极为重要位置.前几年,早熟品种病害重、耐热性差、包心不足、商品性状欠佳;中熟品种短缺,10月上中旬有较长时间市场供应断档;而晚熟品种单一、抗病性较差。针对此种情况,北京市种子管理站与有关单位协作,开始实施了“大白菜早、中、晚熟配套品种的推广”项目,取得了突破性进展。通过试验摸索,我们认为,早熟品种生长期50～60天,如小杂56、小杂60、丰白542等,适宜播期应在7月25日～30日,早播则病害严重.可以于9月中、下旬供应北京市场,中熟品种生长期65～80天,如北京75、北 Chinese cabbage is a must-have dish in Beijing’s autumn and winter seasons and occupies a very important position in vegetable production in the suburbs of Beijing. In previous years, the early-maturing varieties were characterized by heavy disease, poor heat resistance, insufficient heart, and poor commodity traits; Mid-month there is a longer period of time the market supply stall; and a single late-maturing varieties, disease resistance is poor. In response to this situation, Beijing Seed Management Station in collaboration with the relevant units, the implementation of the “Chinese cabbage early, middle and late maturity varieties supporting the promotion of” project, made a breakthrough. Through trial and error exploration, we believe that early maturing varieties of growing period of 50 to 60 days, such as small hybrid 56, small hybrid 60, abundance of 542, etc., suitable sowing date should be July 25 to 30, early sowing the disease is serious. In mid-September, late supply of the Beijing market, medium maturing varieties growing period of 65 to 80 days, such as Beijing 75, North