Apples emit a lot of ethylene gas. It has the effect of speeding up the ripening process of fruits and vegetables kept together with apples. When combined with potatoes, apples prevent them from sprouting.
Some fruits and vegetables (notably apples but also tomatoes, avocados, bananas, muskmelons, pears, plums, and peaches) emit ethylene gas. This has the effect of speeding up the ripening process of fruits and vegetables kept together with them, which is why it is wise to store ethylene producing fruits and vegetables separately. However, when combined with potatoes, Jihyun Ryou says, they have a positive effect, because the ethylene gas prevents the potatoes from sprouting. The design pictured above consists of a wooden box that keeps potatoes in the dark (a more common way to keep them from sprouting), while the holes on top allow them to benefit from the ethylene gas emitted by the apples.
The same design could also be used to accelerate the ripening of tomatoes, a process that is used – on a much larger scale – by food distributors.