１．制种玉米秃顶、结实性差的原因主要有： （１）父母本花期不遇：因亲本播期不当或气候及栽培因素，造成父母本花期不遇，结实性差。 （２）营养不良，特别是缺钾。穗分化期，是营养生长和生殖生长的最快时期，如果养分供应不上，造成部分小花不能发育，顶部迟分化的小花因 1. Seed production of corn bald, the reasons for poor firmness are: (1) parents of the flowering period: due to improper sowing date or weather and cultivation of the parents, resulting in the parents of the flowering period, poor firmness. (2) malnutrition, especially potassium deficiency. Spike differentiation stage is the fastest vegetative and reproductive growth period, if the nutrient supply is not on, resulting in some flowers can not develop, the top of the late differentiation of floret