亲本自交系的纯度与杂交种的增产效果密切相关,生产上必须保持已经纯合稳定的自交系的纯度。但是,由于玉米开花散粉的生物学特性和自交系的遗传组成特点,生产条件又十分复杂,稍有疏忽,自交系变“杂”仍是常有的现象。找出变“杂”的原因,并采取相应的措施,才能在生产上经常保持自交系的纯度。 1 混杂退化原因 1.1 天然杂交。玉米具有雌雄同株异花、雄花先熟、花粉量大而黄轻等特点,最易发生天然杂交,造成生物学混杂。特别是有的自交系雄花不发达,花粉量很少(如 The purity of the parent inbred lines is closely related to the yield increase of the hybrids, and the purity of the inbred lines that have been homozygously stable must be maintained in production. However, due to the biological characteristics of loose flowering maize and the genetic composition of inbred lines, the production conditions are very complicated and negligent. Inbred lines are still common. To find out the cause of “change” and take appropriate measures to maintain the purity of inbred lines in production. 1 mixed degenerative causes 1.1 natural hybridization. Maize with monoecious different flowers, male flowers premature, large amount of pollen and yellow and other characteristics, the most prone to natural hybridization, resulting in mixed biology. In particular, some male inbred lines are underdeveloped with very few pollen (eg