双季杂交稻即一年种植早稻和晚稻两季(有些地区加上麦类称为双三熟制)实现亩产吨粮。这是全国吨粮田开发中把握性最大的种植形式,在南方稻区广泛分布,尤以江苏、浙江、湖南、湖北、广东等省面积最大。全国吨粮田有80％为双季稻吨粮田,还出现很多整建制亩产吨粮田的县(市)。1996年湖南省的株 Two-season hybrid rice that is planted in early rice and late rice two seasons (in some areas plus wheat known as Shuangsan) to achieve tons of grain per mu. This is the most dominant form of cultivation in the development of the nation’s grain crop and is widely distributed in the southern rice area, especially Jiangsu, Zhejiang, Hunan, Hubei and Guangdong provinces. Eighty percent of the national tonnage of grain crop is double-cropped rice and grain cropland, and many counties (cities) with entire tonnage-producing grain fields have also emerged. 1996 strains of Hunan Province