PROBLEM TO BE SOLVED: To provide a method for suppressing greening of potatoes after harvest. SOLUTION: A first process of irradiating a post-harvest potato with far-red light and light in a wavelength range other than far-red light at the same time, and a time period of irradiating a potato with far-red light alone , And a second process including a time period in which far-red light and light in a wavelength range other than far-red light are not irradiated. In the second process, a time zone in which far-red light is not emitted is provided, and a time zone in which far-red light is emitted alone to the potato, and the far-red light and light in a wavelength range other than far-red light are not irradiated. Include the time zone (to be in the dark). [Selection diagram] FIG.【課題】収穫後のジャガイモの緑化を抑制する方法を提供する。【解決手段】収穫後のジャガイモに対して、遠赤色光と遠赤色光以外の波長域の光とを同時に照射する第１過程と、ジャガイモに対して、遠赤色光を単独で照射する時間帯、及び遠赤色光と遠赤色光以外の波長域の光とを非照射とする時間帯を含む第２過程とを備える。第２過程では、遠赤色光を照射しない時間帯を設け、ジャガイモに対して遠赤色光を単独で照射する時間帯、及び遠赤色光と遠赤色光以外の波長域の光とを非照射とする（暗所とする）時間帯を含める。【選択図】図３
