Have you ever wondered why these two colors occur so often? Take these: onion waltnut potato carrot/parsley and even cabbage which can be green or red.
Why these two pigments? Or is it just one pigment and it's just its concentration that makes the difference?
Thanks for any explanations!
A lot of fruit and veg are green when unripe and become brightly coloured when they are ready to eat (obviously not true for all, but most fruit/veg does).
This is probably deliberate as a mechanism to signal to birds and animals that it is ready to eat, so that they can disperse the seeds inside.
Red and Yellow are bright colours not usually seen on plants except of fruit/veg, and flowers (which are brightly coloured to attract bees and whatnot), so it makes sense these could be used as signals.
http://www.rosincerate.com/2015/07/colour-changing-fruits-and-veggies.html
As many plants do, many of vegetable do photosynthesis. For photosynthesis, chlorophylls, which are green, and carotenes, which are yellow to red, play important roles. When chlorophylls get less, you might see yellow to red color due to carotene. When chlorophylls are degraded, they get light brown. In some vegitable, such as tomatoes, lycopene, which is an intermediate of carotene synthesis, is accumulated.
https://en.wikipedia.org/wiki/Lycopene
Another popular pigment is anthocyanin, the color of which is red to purple. Various functions of anthocyanin are suggested from sun-shade, to an antioxidant, to attracting birds in fruits.
