UCSB Science Line
Sponge Spicules Nerve Cells Galaxy Abalone Shell Nickel Succinate X-ray Lens Lupine
UCSB Science Line
How it Works
Ask a Question
Search Topics
Our Scientists
Science Links
Contact Information
How does color affect plant growth?
Question Date: 2012-12-05
Answer 1:

This is an interesting question. First, let's clarify something: the "color" of light doesn't just consist of the visible colors we can see. It turns out that the "visible spectrum" is only a very small part of all kinds of light, or electromagnetic radiation. When light from the sun comes into our atmosphere, it's not just a mix of different colors, but there is also some UV and infrared light in the mixture. There is what we would call a certain "distribution" (or relative amounts) of visible, UV, and infrared light in this mixture. So I think what your question comes down to is this: how would changing the relative amounts of the different kinds of light affect plant growth?

Let's consider the visible part of the spectrum first. I think most people would agree that plants are green in general. They are green because they reflect green light. So changing the amount of green light in the distribution shouldn't really affect how plants grow, since they don't use it for their metabolic processes. It turns out that plants use mostly red and blue light. Let's think about how the color of sunlight changes over the year. As the days grow longer in the spring and summer, plants start to grow. Sunlight is mostly blue in this time of year, so blue light tends to increase stem and leaf growth. Later, as summer progresses, sunlight becomes predominantly red and plants flower and bear fruit that becomes ripe.

Now let's think about what happens when we increase UV or infrared. It depends on the kind of plant we're talking about, but in many cases, increased UV or infrared tends to damage plants. I hope this helps!

Answer 2:

Plants absorb different colors of light for use as energy in growing. By and large, plants absorb red light and use it, and green light doesn't help them (that's why plants are green: the green light reflects off of them).

Click Here to return to the search form.

University of California, Santa Barbara Materials Research Laboratory National Science Foundation
This program is co-sponsored by the National Science Foundation and UCSB School-University Partnerships
Copyright © 2020 The Regents of the University of California,
All Rights Reserved.
UCSB Terms of Use