Do Different Colors of Light Affect Plant Growth?

Students, even when they are in high school and college, enjoy planting seeds and watching plants grow from them.

From a teaching perspective, a wonderful thing about growing plants is they give so many opportunities for students to use the scientific method to develop and test hypotheses.

It is a generally accepted principle that visible light supports maximal photosynthesis in green plants. Wavelengths of life between 610 and 700 nanometers, supplemented by blue and green light, is optimal for germination, bud development, flowering, and plant growth.

Different wavelengths of light, however, have specialized effects in plants that your students can easily test.

How Different Colors of Light Affect Plant Growth

Consider these statements about how different colors of light affect plant growth—which your students can formulate as testable hypotheses and then test with simple experiments:

The color of light affects plant growth, but the effect of color is more noticeable in low-intensity light, for example, growing plants under the glazed glass windows of a greenhouse or on the windowsill at home or in a classroom.

• Rates of photosynthesis increase under blue and red light, but blue and yellow light have little effect.
• Blue light increases the production of chlorophyll in seedlings.
• Some seedlings can’t sprout without exposure to blue light.
• Red light increases flowering and fruiting.
• The amount of light to which a fruiting plant is exposed affects the sugar content, tartness, and size of its fruit.

Students who have a suitable math background can explore the concept of the daily light integral, known in horticulture as the DLI. They can test hypotheses about the relationship of the DLI to plant growth. They can test the relationship of the DLI to plant growth when certain wavelengths of light are enhanced or excluded.

And your students can test hypotheses that UV light may be harmful to plants, but violet light may stimulate all stages of growth. They can test their hypotheses that blue light is helpful only in the earliest stages of growth, or whether it may be helpful at all stages of growth.

Students can test the idea that yellow light doesn’t stimulate the production of chlorophyll, but plants that are grown under yellow light are healthier. They can test their hypothesis that red light makes flowers bloom.

Use experiments to Help Your Students

Experiments involving the effects of specific spectra of visible and UV light have different effects on plant growth are easy to set up on your own, but they are even easier with Modern Biology.

With Modern Biology’s IND-32: Plant Pigment/Peroxidase Analysis, your students can even begin to characterize the carotene, anthocyanidin, and lycopene pigments they extract from common fruits and vegetables by comparing them to albumin and cytochrome-C with electrophoresis.

Why choose Modern Biology experiments

Every experiment kit made by Modern Biology supports scientific thinking. Students test their hypotheses. They never just watch demonstrations. They are never limited to facts and vocabulary.

Every Modern Biology helps students develop the manual dexterity and note-taking skills that they will carry to future study and their careers. Modern Biology is developed by working scientists for future working scientists.

Every Modern Biology kit includes all the reagents and test materials teachers need for their laboratory exercise. There is no need to order separate reagents, no fussing about missing shipments, and no checking out lab materials from the supply room.

Modern Biology supplies the safe, non-toxic, reliable reagents and measurement materials you need for every laboratory exercise. And because every Modern Biology experiment is available at a fixed cost, it’s easier to budget your supply cost for each class for each term.

Want to learn more? Email Modern Biology or call us at (765) 446-4220 Monday through Friday from 9 to 5 Eastern time.