MadSci Network: Botany
Query:

Re: What happensif a plant is only allowed to see light a few minutes a day?

Date: Sat Mar 4 10:13:06 2000
Posted By: Peter Minorsky, Faculty, Biology and Environmental Sciences, Western Connecticut State University
Area of science: Botany
ID: 951258165.Bt
Message:

Dear Lewis:

Five minutes of light per day isn’t very much. Plants need light to make their own food through the process called photosynthesis. Without sufficient light, the plant will, in the long term, starve to death.

In the short term, however, a very curious thing will happen....the plant will start to elongate very dramatically. It does so in a last ditch effort to reach any available light. All available resources within the plant will be marshalled in a vain attempt to reach the light (which you so cruelly have taken away!). The plant will grow tall, pale and spindly, and will eventually topple over and die.

There is a pigment in the plant called phytochrome that controls this process (a pigment is simply a molecule that absorbs visible light). Phytochrome is a bit like a light switch: it exists in two conformations, Pr and Pfr. Red light causes phytochrome to be in the Pfr form and this promotes normal growth. Darkness causes phytochrome to accumulate in the Pr form and this promotes the last-ditch growth described in the first paragraph. By complex mechanisms. the Pr form alters the normal growth hormone concentrations within the plant, thereby causing the last-ditch spurt of growth


Current Queue | Current Queue for Botany | Botany archives

Try the links in the MadSci Library for more information on Botany.



MadSci Home | Information | Search | Random Knowledge Generator | MadSci Archives | Mad Library | MAD Labs | MAD FAQs | Ask a ? | Join Us! | Help Support MadSci


MadSci Network, webadmin@www.madsci.org
© 1995-2000. All rights reserved.