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  #31  
Old 11-01-2011, 03:19 AM
Chana Masala
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Thanks for being positive.

Plants and Altitude Revisited
Plants and Altitude

The physiological ecology, and particularly the leaf gas exchange (mainly CO2 and O2) of plants growing at high altitude, has been receiving renewed attention (e.g. Smith and Donahue, 1991; Terashima et al., 1995; Sakata and Yokoi, 2002).

In considering the effect of altitude on whole plant physiology and ecology all factors of the environment must be taken into account, not only leaf gas exchange under saturating light and otherwise optimal conditions. For example, shortwave solar radiation increases with altitude while air temperatures usually, but not always, fall (Gale, 1972a, b). For many hours of the day at high elevation the maximum solar radiation may indeed be well above the saturation levels for photosynthesis of C3 plants. Even so, on clear sky summer days, plants are exposed to less than saturating light for most of the daylight hours of the day. At such times of the day, plants growing at high elevations have a relative advantage, as incident sunlight increases with altitude.

Gale (1972b, 1973) predicted and demonstrated a potential increase of transpiration with altitude when there is less than the average lapse rate of ambient temperature (about 0.6 C/100 m at mid-latitudes). This results from the higher total radiation absorbed by leaves, the increase in the diffusion coefficient of water vapour in air at reduced barometric pressure and the increased density gradient of H2O vapour from the leaf to the ambient air. This is contrary to the case of CO2 influx into leaves, where the two diffusion factors tend to cancel out (Gale, 1972a). Consequently, transpiration rates at high altitude may be very high, as for example in Mediterranean climates where temperature inversions are common (Cohen et al., 1981). Under such conditions and where water is available and stomata remain open, a 1000 m elevation above sea level may bring about a doubling of transpiration rates. von Caemmerer and Farquhar (1981) showed how vapour efflux through the stomata may impede CO2 diffusion influx and hence photosynthesis. Consequently, the effect of transpiration on photosynthesis should also be studied and included in the analysis of the effect of altitude on leaf gas exchange. Moreover, exposure to conditions that induce high rates of transpiration may exhaust available water. This results in closure of stomata and hence reduction in photosynthesis and may also bring about a more xeromorphic plant species composition (Cohen et al., 1981).

A comprehensive analysis of altitude effects on plants would include radiation and other meteorological conditions over the course of the day and growing season. Exceptional, if not unusual events, such as temperature inversions, would also be considered. Apart from the above, other important factors to be taken into account are the physiological type of the plants (e.g. meso- or xeromorphic, C3 or C4) response of the whole plant and the edaphic environment. Cohen et al. (1981) and Friend and Woodward (1990) described early work in this direction, combining field and laboratory experimentation and modelling.

Annals of Botany 94/2, Annals of Botany Company 2004; all rights reserv

I guess GMT needs to go read some more books eh!
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  #32  
Old 11-01-2011, 03:23 AM
hempy
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Quote:
Originally Posted by Chana Masala View Post
Thanks for being positive.

Your welcome i am a nice guy if i am shown some respect.
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  #33  
Old 11-01-2011, 03:25 AM
Chana Masala
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Effect of Atmospheic Pressure...

http://contrails.iit.edu/DigitalColl...6article13.pdf


Hypobaric Biology: Arabidopsis Gene Expression at Low Atmospheric Pressure1[w]

Hypobaric Biology: Arabidopsis Gene Expression at Low Atmospheric Pressure

Arabidopsis

http://en.wikipedia.org/wiki/Arabidopsis
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  #34  
Old 11-01-2011, 09:45 AM
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lol chana, you post something that argues against yourself, then misunderstand it and think it proves you right.
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  #35  
Old 11-01-2011, 12:33 PM
Chana Masala
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lol chana, you post something that argues against yourself, then misunderstand it and think it proves you right.
Get off your high horse. Didnt realize you were one of the guys that mapped the cannaibis gene and also figured out how to make your shit not stink. Must be all those grade school science books you read.

Since when does rain have nothing to do with evaporation?

Thanks for coming out,

CM
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  #36  
Old 11-01-2011, 01:29 PM
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Quote:
Originally Posted by Chana Masala View Post
I guess GMT needs to go read some more books eh!
I deliberately avoided addressing anyone specifically. I'm just amazed that science holds such little value in the educational systems of so many schools these days. You started the mud slinging here not me.

And to answer your question, since the big bang. Air pressure will determine whether or not the clouds are able to release the moisture they hold.

Now be nice or you may not get the chance to learn anything else.
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  #37  
Old 11-01-2011, 01:50 PM
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howdy mns

am not please to read such malice and rude comment....am ashame to read such at mns.

am not credit scientist....only am human experience. think to that and think to what make credit science. hehe

perspective and parameter make science, such think to that. one perspective science alive and utilize human with ego.

much respect to all mns community. please treat to each other with love and compassion.

to isolate such variable useful as not useful....depend with perspective.

GMT am interest with you comment to lettuce and wheat variance page 2
https://www.mrnice.nl/forum/131460-post16.html

also with respect to barometric pressure to affect transpiration within plant.

with not speculate cost or possible or not possible. refute such fact with respect to variable and analysis. please not with refute with malice and hate.

each and all human same qualify to science. data collect and analysis with individual perspective.

much respect to all at mns, with not to include rude comment.
such DM say same side.

positive vibration
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  #38  
Old 11-01-2011, 02:39 PM
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tin I'm sorry, I have tried, and I swear I'm not trying to be insulting towards you here, but I can't read what you wrote, so have no way to respond to you. Could you perhaps type your posts out in your own language and then translate them using either google or babelfish? I think you'd find it easier and I know I would find it easier to read your post that way.
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  #39  
Old 11-01-2011, 02:46 PM
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howdy GMT

much respect.
pardon am lack to communicate you GMT. perhap friend to translate.

positive vibration
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  #40  
Old 11-01-2011, 02:49 PM
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this is by far the easier way to translate

Yahoo! Babel Fish - Text Translation and Web Page Translation

give it a try
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