1　影响玉米制种产量的因素1.1　施肥不合理。一是量少 ,亩施尿素 15～ 2 0 kg、磷酸二铵 10 kg,虽然比大田玉米施肥量增加了不少 ,但还是远远不能满足玉米制种高产的需要。二是配方不合理 ,重氮磷肥轻钾肥和微肥。根据最小养分率 ,钾肥和微肥往往成为限制因素 ,氮肥、磷肥也不 1 factors affecting the yield of corn seed 1.1 fertilization unreasonable. First, the amount of less acres of urea 15 ~ 20 kg, 10 kg of diammonium phosphate, although more than a large amount of field corn fertilizer, but still far can not meet the needs of high yield of corn seed. Second, the formula is unreasonable, heavy nitrogen fertilizer and potassium fertilizer. According to the minimum nutrient rates, potash and micronutrients tend to be the limiting factor, neither nitrogen nor phosphate fertilizer