This invention includes the method in order to obtain the long day onion plant which includes the bulb whose taste is little harshly, and the onion which catches. This invention offers also the reagent and the material which can be used in the method in order to obtain this onion.本発明は、辛味の少ない鱗茎を含む長日タマネギ植物、およびかかるタマネギを得るための方法を含む。本発明は、かかるタマネギを得るための方法において用いられ得る試薬および材料も提供する。