In the picture you see roots hanging in the air and a nozzle which is spraying the roots with a nutrient solution with certain intervals. This is called aeroponics and is a method developed by NASA when they needed a way to farm in space, without using soil.
It turned out that with aeroponics, the plants grew better than with any other type of farming method. The roots, as many other cells, need oxygen and nutrients to survive. Letting the roots be suspended in the air allows for oxygen to diffuse freely, rather than being actively transported from shoots and leaves. This saves a tremendous amount of energy – energy which the plant now can use to grow.