Subject: Re: absorption
From: [email-masked] (Jonathan B. Marder)
Date: Tue, 31 May 1994 06:05:21 GMT
Newsgroups: bionet.photosynthesis

In article <[email-masked]> [email-masked] (Carolyn S. Ogren) writes:
>Subject: absorption
>From: [email-masked] (Carolyn S. Ogren)
>Date: 28 May 1994 16:27:44 GMT

>The absorption spectrum for plant chlorophyll shows that there is
>little absorption of green light. I understand that is why plants
>are green. But why don't plants absorb, use, these wavelengths?
>Isn't this a "waste of a valuable resource?
>--
Don't be fooled by Absorbance spectra - absorbance is a logarithmic
scale.  If a single leaf transmits 63% of the green light (0.2 optical
density), then a stack of five leaves (1 O.D)would transmit only 10% i.e.
90% absorbed AND USED.  In practice this means that crop canopies absorb and
utilise green light for photosynthesis.

BTW John Cheeseman is right in saying that some of the green absorbance is due
to accessory pigments (which channel the energy to chlorophyll).

__
Jonathan B. Marder                 '
Department of Agricultural Botany  |     Internet: [email-masked]
The Hebrew University of Jerusalem | /\/ Bitnet:   MARDER@HUJIAGRI
Faculty of Agriculture             |/  \ Phone:    (08 or +9728) 481918