How would a tomato look under blue light?

Tomatoes would appear black under blue light because they do not reflect blue light.

Most fruits and vegetables appear red, orange, or yellow because they contain pigments called carotenoids. Carotenoids absorb blue and green light and reflect red, orange, and yellow light. However, tomatoes also contain a pigment called chlorophyll, which absorbs red and blue light and reflects green light. This means that tomatoes appear red under white light, but they would appear black under blue light because they do not reflect any blue light.