以增强适应性为主线，以优异种质引进、创新与利用为基础，坚持“大规模、多地点和持续性”的育种思路，实施多地点、高密度、少施肥和少灌水的技术路线，选育出陕单609玉米品种。陕单609具有高产稳产、耐密植、抗旱、品质优良、产量潜力大和适应性广的特点。分析陕单609玉米品种的选育背景和育种过程，总结玉米自交系91227和陕单609玉米杂交种的特征特性。玉米品种改良要重视外来玉米种质的利用，强化育种环境的选择压力，创新玉米品种的推广方式。

Based on the introduction, innovation and utilization of excellent germplasm, the breeding strategy integrated the breeding ideas of "large population, multi-environment and sustainability", breeding technology system of multi-location, high density, low fertilization and irrigation for enhance adaptability of maize varieties. The breeding of maize hybrid Shaandan609 with high and stable yield, high density tolerance, drought, good quality, high yield potential characteristics. Breeding background and breeding process of maize hybrid Shaandan609 were summarized, and the characteristics of the maize inbred line 91227 and maize hybrid Shaandan609 were analyzed. Breeders should increase selection pressure in high-yield maize breeding in order to improve the utilization of exotic maize germplasm. Extension method of maize variety was innovated.

国家现代玉米产业技术体系陕西关中综合试验站项目（CARS-02-64）、“七大农作物育种”试点专项（SQ2016ZY03002）