Ed, We know that trees breathe through pores ( stomata ) on the leaves underside. But in winter how do trees respirate? I would suppose it would be through their roots. After all that is one theory why baldcypress produce those strange knees.
James Parton On Mar 18, 9:32 pm, "Edward Frank" <[email protected]> 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. > > 23605.nce001.jpg > 17KViewDownload --~--~---------~--~----~------------~-------~--~----~ Eastern Native Tree Society http://www.nativetreesociety.org Send email to [email protected] Visit this group at http://groups.google.com/group/entstrees?hl=en To unsubscribe send email to [email protected] -~----------~----~----~----~------~----~------~--~---
