17-year study shows CO2 enrichment boosts yields of sour orange trees
Between November of 1987 and January of 2005, the longest CO2-enrichment study of a long-lived woody plant species ever to be conducted was carried out at Phoenix, Arizona (USA), by an international team of researchers. The results show elevated levels of CO2 boost both the total amount of biomass produced by the trees as well as the harvestable yield, that is, fruits. The effects were long lasting.
The findings have been reported in the October issue of Global Change Biology. They confirm that an increase in atmospheric CO2 could be beneficial to many types of vegetation. However, scientists have warned that these effects could be largely offset by an increase in atmospheric ozone (earlier post).
The tests where organised by Bruce Kimball of the US Agricultural Research Service's Arid Land Agricultural Research Center, Sherwood Isdo from the Center for the study of Carbon Dioxide and Global Change, Stephanie Johnson of the University of Montana and by Matthias Rillig of the Institute of Biology at the Free University of Berlin. They were initiated with the out-of-doors planting of eight sour orange (Citrus aurantium L.) seedlings, and with the initial project researchers surrounding pairs of the seedlings with clear-plastic-wall open-top chambers, within which four of the trees were exposed to a continual bottom-to-top flow of ambient air, while the other four trees were exposed to a similar 24-hour 7-day-per-week upward flow of air enriched with an extra 300 ppm of CO2. The scientists state that "the trees were fertilized and flood irrigated similar to practice in commercial orchards so as to maintain ample nutrients and soil moisture."
So what was learned from the historic 17-year experiment? In terms of total biomass production, which was the primary focus of the summary report, Kimball and collegues state that the CO2-enriched to ambient ratio of annual wood plus fruit production "peaked in years 2-4 of the experiment at about 2.4," but that "following the peak, there was a decline through year 8." Thereafter, they found that the annually-produced-biomass ratios "were more or less at a plateau that corresponded with the value of the ratio at final harvest of 1.69."
In terms of harvestable yield, that is, fruit production, lead author Kimball writes that "the cumulative amount of biomass due to fruit production over the duration of the experiment was increased 85% due to elevated CO2," which increase "was entirely from an increase in fruit number":
energy :: sustainability :: biomass :: bioenergy :: biofuels :: carbon dioxide :: climate change :: crops :: agriculture ::
In addition, the scienistst report that "the vitamin C content of the fruit was increased 7% based on samples taken from the fourth through the 12th years of the experiment." Consequently, not only were there a whole lot more oranges produced by the trees in the CO2-enriched chambers, a whole lot more better-quality oranges were produced.
In their concluding discussion of one of the major implications of the study, the researchers write that "rather than a continual acclimation" - i.e., rather than a gradual long-term decline in the aerial fertilization effect of the extra 300 ppm of CO2 supplied to the CO2-enriched trees "instead there was a sustained enhancement of about 70% in annual fruit and incremental wood production over the last several years of the experiment."
This observation thus led them to conclude that "the effects of elevated CO2 on trees can be large and sustained for many years," as they indeed demonstrated to be the case with sour orange trees, there having been a 70% sustained increase in biomass production over the entire last decade of the study in response to the 75% increase in the air's CO2 content employed throughout the experiment.
References
Kimball, B.A., Idso, S.B., Johnson, S. and Rillig, M.C. 2007. "Seventeen years of carbon dioxide enrichment of sour orange trees: final results", Global Change Biology 13 (10): 2171-2183, doi:10.1111/j.1365-2486.2007.01430.x
Biopact: MIT study: human-generated ozone could damage crops - temperate regions hit hard, tropics spared - October 30, 2007
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The findings have been reported in the October issue of Global Change Biology. They confirm that an increase in atmospheric CO2 could be beneficial to many types of vegetation. However, scientists have warned that these effects could be largely offset by an increase in atmospheric ozone (earlier post).
The tests where organised by Bruce Kimball of the US Agricultural Research Service's Arid Land Agricultural Research Center, Sherwood Isdo from the Center for the study of Carbon Dioxide and Global Change, Stephanie Johnson of the University of Montana and by Matthias Rillig of the Institute of Biology at the Free University of Berlin. They were initiated with the out-of-doors planting of eight sour orange (Citrus aurantium L.) seedlings, and with the initial project researchers surrounding pairs of the seedlings with clear-plastic-wall open-top chambers, within which four of the trees were exposed to a continual bottom-to-top flow of ambient air, while the other four trees were exposed to a similar 24-hour 7-day-per-week upward flow of air enriched with an extra 300 ppm of CO2. The scientists state that "the trees were fertilized and flood irrigated similar to practice in commercial orchards so as to maintain ample nutrients and soil moisture."
So what was learned from the historic 17-year experiment? In terms of total biomass production, which was the primary focus of the summary report, Kimball and collegues state that the CO2-enriched to ambient ratio of annual wood plus fruit production "peaked in years 2-4 of the experiment at about 2.4," but that "following the peak, there was a decline through year 8." Thereafter, they found that the annually-produced-biomass ratios "were more or less at a plateau that corresponded with the value of the ratio at final harvest of 1.69."
In terms of harvestable yield, that is, fruit production, lead author Kimball writes that "the cumulative amount of biomass due to fruit production over the duration of the experiment was increased 85% due to elevated CO2," which increase "was entirely from an increase in fruit number":
energy :: sustainability :: biomass :: bioenergy :: biofuels :: carbon dioxide :: climate change :: crops :: agriculture ::
In addition, the scienistst report that "the vitamin C content of the fruit was increased 7% based on samples taken from the fourth through the 12th years of the experiment." Consequently, not only were there a whole lot more oranges produced by the trees in the CO2-enriched chambers, a whole lot more better-quality oranges were produced.
In their concluding discussion of one of the major implications of the study, the researchers write that "rather than a continual acclimation" - i.e., rather than a gradual long-term decline in the aerial fertilization effect of the extra 300 ppm of CO2 supplied to the CO2-enriched trees "instead there was a sustained enhancement of about 70% in annual fruit and incremental wood production over the last several years of the experiment."
This observation thus led them to conclude that "the effects of elevated CO2 on trees can be large and sustained for many years," as they indeed demonstrated to be the case with sour orange trees, there having been a 70% sustained increase in biomass production over the entire last decade of the study in response to the 75% increase in the air's CO2 content employed throughout the experiment.
References
Kimball, B.A., Idso, S.B., Johnson, S. and Rillig, M.C. 2007. "Seventeen years of carbon dioxide enrichment of sour orange trees: final results", Global Change Biology 13 (10): 2171-2183, doi:10.1111/j.1365-2486.2007.01430.x
Biopact: MIT study: human-generated ozone could damage crops - temperate regions hit hard, tropics spared - October 30, 2007
Article continues
Wednesday, October 31, 2007
The bioeconomy at work: scientists make gold nanoparticles from soybeans
The green discovery has created a large positive response in the scientific community. It sets up the beginning of a new knowledge frontier that interfaces plant science, chemistry and nanotechnology. Some are jubilant because the discovery will ensure that gold nanoparticles-based nanomedicine products would be made available even to the less developed regions of the world where farmers grow the renewable biomass needed to make the material.
MU researchers Kattesh Katti, Raghuraman Kannan, and Kavita Katti led a team of scientists that have discovered how to make gold nanoparticles using gold salts, the carbohydrates contained in soybeans and water. No other chemicals are used in the process, which means it could have major environmental implications for the future.
Researchers believe that gold nanoparticles are set to be used in a large number of new processes and products, from the capture of toxins and lethal microbes to solar cells, cancer therapies, next generations of computer and telecommunications tools, and in the production of 'smart' electronic devices and sensors. By making them from renewable biomass the bioeconomy receives another boost.
Kattesh Katti, professor of radiology and physics in MU's School of Medicine, senior research scientist at MURR, director of the University of Missouri Cancer Nanotechnology Platform and one of the fathers of the use of gold nanoparticles in nanomedicine comments on the advantages of the green process his team developed:
Gold nanoparticles are tiny pieces of gold, so small that they cannot be seen by the naked eye. While the nanotechnology industry is expected to produce large quantities of the particles in the near future, researchers have been worried about the environmental impact of the global nanotechnological revolution.
To complete the formation of gold nanoparticles, harmful synthetic chemicals such as hydrazine, sodium borohydride and dimethyl formamide are needed in lengthy synthetic processes. These chemicals pose handling, storage, and transportation risks that add substantial cost and difficulty to gold nanoparticle production. These harmful chemicals also make it impractical, if not impossible, to produce gold nanoparticles in-vivo.
The MU research team turned to Mother Nature for assistance and alternatives. Amazingly, they found that by submersing gold salts in water and then adding soybeans, gold nanoparticles were generated. The water pulls a phytochemical(s) out of the soybean that is effective in reducing the gold to nanoparticles. A second phytochemical(s) from the soybean, also pulled out by the water, then interacts with the nanoparticles to stabilize them and keep them from fusing with the particles nearby. The process creates nanoparticles that are uniform in size in a 100 percent green process:
energy :: sustainability :: biomass :: bioenergy :: biotechnology :: nanotechnology :: green chemistry :: nanoparticles :: bioeconomy ::
The new discovery has created a very large positive response in the scientific community. Researchers from as far away as Germany have been commenting on the discovery's importance and the impact it will have in the future.
Katti, Kannan, Henry White, MU professor of physics, and Kavita Katti, a senior research chemist, have filed a patent for the new process and developed a new company, Greennano Company, which focuses on development, commercialization and world wide supply of green nanoparticles for medical and technological applications.
Dr. Katti's novel methodology to develop gold nanoparticles with soy will have important implications as the field of nanotechnology blossoms and has greater needs for 'green' synthesis of gold based nanoparticles. It is a very important first step. - Sam Gambhir, director of the Center for Cancer Nanotechnology Excellence at Stanford University
The research team includes Kattesh and Kavita Katti, Kannan, post-doctoral scientists Satish Nune and Nripin Chanda, and Mizzou graduate student Swapna Mekapothula. The research was funded by grants from the National Cancer Institute. Katti recently presented the work at the annual National Cancer Institute Alliance for Nanotechnology in Cancer Investigator's meeting in October. He also will be presenting the research at the Fourth International Congress of Nanotechnology and the Clean Tech World Congress held in San Francisco in early November.
The discovery also could open doors for additional medical fields, as some of the chemicals used to make nanoparticles are toxic to humans. Having a 100 percent natural process could allow medical researchers to expand the use of the nanoparticles.
Dr. Katti's discovery of green and non-toxic gold nanoparticles is a significant step to help alleviate the pain and suffering of patients with Pseudoxanthoma elasticum (PXE) says Frances Bernham, president of the National Association of Pseudoxanthoma elasticum. PXE causes changes in the retina of the eye that results in significant loss of central vision.
References:
Eurekalert: MU researchers go nano, natural and green - October 31, 2007.
United States Patent Application: 20070051202: Raghuraman Kannan et al. "Methods and articles for gold nanoparticle production" - March 8, 2007
University of Missouri: Kattesh V. Katti, Professor of Radiology & Physics Senior Research Scientist MU Research Reactor homepage.
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