MadSci Network: Botany

Re: Why don't plants respond equally to colors? What is this phenomenom called?

Date: Wed Mar 31 23:24:32 1999
Posted By: Maggie Guo, Grad student, Plant Physiologu and Molecular Biology Program, Dept.of Plant Biology, UIUC
Area of science: Botany
ID: 922044615.Bt


I think the word "color" in your questions may refer to different kinds of light. The part of sunlight which can reach our earth is a complex of light with different color, blue/purple light and red light can cause more reactions.

Plants need light to produce some chemicals for their growth, right? This procedure, which is called photosynthesis, happens in chloroplast of plant and needs energy. The light, although is not touchable, has both properties of particles and waves. The particle property means that light consists of photons, a kind of small particle. The wave property is charicterized by wavelength. Each photon contains energy, and the amount of energy is related to wavelength: the shorter the wavelength, the higher the energy. Furthermore, among the sunlight on earth, blue and purple light have shortest wavelength, imply that they have highest energy, that can explain why chloroplast prefer them. But besides this, red light can also induce strong reaction in chloroplast, its mechanism, sorry, I am not clear yet.

Red light can influence plant growth in another way. There is a kind of special protein complex in plant named phytochrome, which is sensitive to red/far red light. It is said that phytochrom can induce some changes in genetic materials of plants, thus regulate the growth of plants. However it's not completely clear at this point.

Hum, you've asked a very broad question. :) Now I can only explain it very simple to you, because it's very complicated, but also very interesting. If you're still interested in it, you can try to read some books about plant physiology, I think my textbook, Plant Physiology by Taiz & Zeiger maybe too deep to you, but who knows? It doesn't hurt to try. I am not sure about other reference book yet. On internet there is no much proper sites, maybe we should establish one!

Have I answered your question? Hope you enjoy the knowledge of plant!


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