河北南宫四区巩家洼社由于1953年未选种留种,到1954年播种时绝大部份种籽是轧花厂供给的,种籽纯度只有67.5%,除去虫咬籽、破籽、不成熟籽等以外,有效种籽为77.6%,保苗工作受到不少影响。1954年秋季由于进行了选种留种工作,并在1955年春进行了粒选,使种籽的纯度和有效籽都提高到80%以上,打下了全苗增产的基础。选种留种在第一年开始进行的时候,当然还不能 Gongjiawa District, Hebei Province, four districts Gongjiawa depression since 1953 did not choose to stay species, to 1954 when planting most of the seeds are ginning plant supply, the purity of only 67.5% seeds, remove insects biting seeds, broken seeds, Immature seeds, etc., the effective seed is 77.6%, nursery seedlings are subject to a lot of work. In the fall of 1954, seed selection was carried out and seeds were pelleted in the spring of 1955, raising seed purity and effective seeds to more than 80%, laying the foundation for increasing seedling yield. Of course, we can not choose the species to be planted at the beginning of the first year