Neil- I wonder if you know by how much, height would vary due to the tree's "daily cycle"? -Don
> Date: Thu, 19 Mar 2009 05:07:55 -0700 > Subject: [ENTS] Re: Tree Respiration > From: [email protected] > To: [email protected] > > > > Karl, > > as i understand this is for art and you were asking for respiration, > please forgive this slight tangent. > > tree stems go through a daily cycle - shrinking during growing season > days as the Sun pulls water out of the system and then swelling at > night as they re-charge their water balance. > > makes me think of breathing in & out. > > neil > > On Mar 18, 10:11 pm, Karl Cronin <[email protected]> wrote: > > Thanks Ed! > > > > This is extremely useful. > > > > While common knowledge for ENTS, > > I feel the nuances of these cycles are not part of the general > > public's knowledge bank > > (certainly weren't part of mine until just now). > > > > I look forward to shedding light on photorespiration > > but comparing it to our own daily and yearly cycles. > > > > Cheers! > > > > Karl > > > > Karl Cronin > > dry earth > > > > e: [email protected] > > p: (718)916-3528 > > w: dryearth.org > > face:http://tinyurl.com/dryearth > > tweet: dryearth > > > > Check out our new website!www.dryearth.org > > > > //////////////////////////////////////////////////// > > > > On Mar 18, 2009, at 9:32 PM, Edward Frank wrote: > > > > > Karl, > > > > > During the daylight the plant takes in carbon dioxide through he > > > leaves. and through the process of photosynthesis produces sugars, > > > and expels oxygen. Also during the same time as photosynthesis is > > > taking place is the reverse process of respiration in which some of > > > the oxygen and sugar is burned to produce energy and carbon > > > dioxide.- an indirect method to convert light energy from the sun to > > > chemical energy. Plants can only perform photosynthesis during the > > > daytime. At night the trees at a slower rate absorb oxygen from the > > > leaves and burns sugars producing energy and carbon dioxide that is > > > expelled from the leaves. In the fall deciduous trees drop their > > > leaves in the autumn in temperate climates, so they are unable to > > > perform photosynthesis in the winter. They still perform respiration > > > in order to use stored energy and survive during these times. > > > > > So there is a day/night cycle involved and a spring through fall > > > versus winter cycle. > > > > > Ed > > > > > --------------------------------------- > > >http://www.sciencedaily.com/releases/2004/07/040723093305.htm > > > ScienceDaily (July 26, 2004) — A biological process in plants, > > > thought to be useless and even wasteful, has significant benefits > > > and should not be engineered out -- particularly in the face of > > > looming climate change, says a team of UC Davis researchers. > > > > > The researchers have found that the process, photorespiration, is > > > necessary for healthy plant growth and if impaired could inhibit > > > plant growth, particularly as atmospheric carbon dioxide rises as it > > > is globally. Their findings are published this week in the > > > Proceedings of the National Academy of Sciences. > > > > > Over the past two hundred years, scientists have come to understand > > > that plants are amazing biochemical factories that harness energy > > > from sunlight to convert water and carbon dioxide into sugars that > > > fuel the plant, while giving off oxygen. > > > > > Though elegantly simple in concept, this process, known as > > > photosynthesis, is remarkably complex in detail. And for years, > > > researchers have been puzzled by another process, photorespiration, > > > which seems to have annoyingly associated with photosynthesis down > > > the evolutionary pathway. > > > > > Photorespiration has appeared to be downright wasteful because it > > > virtually undoes much of the work of photosynthesis by converting > > > sugars in the plant back into carbon dioxide, water and energy. > > > > > Believing that photorespiration is a consequence of the higher > > > levels of atmospheric carbon dioxide in long past ages, many > > > scientists concluded that photorespiration is no longer necessary. > > > Some have even set about to genetically engineer crop plants so that > > > the activity of the enzyme that initiates both the light-independent > > > reactions of photosynthesis and photorespiration would favor > > > photosynthesis to a greater extent and minimize photorespiration. > > > > > The result, they have thought, would be more productive crop plants > > > that make more efficient use of available resources. > > > > > But the new UC Davis study suggests that there is more to > > > photorespiration than meets the eye and any attempts to minimize its > > > activity in crop plants would be ill advised. > > > > > "Photorespiration is a mysterious process that under present > > > condition dissipates about 25 percent of the energy that a plant > > > captures during photosynthesis," said Arnold Bloom, a professor in > > > UC Davis' vegetable crops department and lead researcher on the > > > study. "But our research has shown that photorespiration enables the > > > plant to take inorganic nitrogen in the form of nitrate and convert > > > it into a form that is useful for plant growth." > > > > > The UC Davis team used two different methods to demonstrate in both > > > wheat and Arabidopsis, a common research plant, that when plants are > > > exposed to elevated levels of atmospheric carbon dioxide or low > > > levels of oxygen -- both conditions that inhibit photorespiration -- > > > nitrate assimilation in the plant's shoot slows down. Eventually, a > > > shortage of nitrogen will curtail the plant's growth. > > > > > "This explains why many plants are unable to sustain rapid growth > > > when there is a significant increase in atmospheric carbon dioxide," > > > said Bloom. "And, as we anticipate a doubling of atmospheric carbon > > > dioxide associated with global climate change by the end of this > > > century, our results suggest that it would not be wise to decrease > > > photorespiration in crop plants." > > > > > The UC Davis study was supported by the National Science Foundation, > > > the U.S. Department of Agriculture and an Israel Binational > > > Agricultural Research and Development Fund fellowship. > > > > > -------------------------------------------------------------- > > > > > Breathing, the inspiration and expiration of air by animals, is not > > > the same as respiration. Both animals and plants respire, but plants > > > neither breathe nor have specialized respiratory systems as do > > > animals. In plants, gases diffuse passively into the plant (through > > > the stomata or directly into the epidermal cells) where they come > > > into contact with the moist cellular membranes and then move in > > > water along diffusion gradients between and within cells. No special > > > carriers (such as the hemoglobin of human blood) or organs (such as > > > lungs or gills) aid in the diffusion. > > > > > Glucose is the originating molecule for respiration; other reserve > > > foods either follow different utilization pathways or, in the case > > > of complex carbohydrates, are broken down to glucose before > > > undergoing respiratory oxidation. > > _________________________________________________________________ Express your personality in color! 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