In the scorching summer heat of the Chihuahuan Desert in southwest Texas, air temperatures can hover around 97°F (36°C) while at the surface of the soil temperatures can exceed 158°F (70°C).
A \"living rock\" cactus (Ariocarpus fissuratus) in a large container on the roof of the biology building of Occidental College, Los Angeles, in June 2008 after 8 days of high temperatures. This particular plants was embedded in sandy soil with surface rocks. Scale bar = 10 mm. Credit: Gretchen B. North, Occidental College, Los Angeles
Encountering these extreme temperatures, plants must utilize creative methods to not only survive but thrive under these difficult and potentially lethal conditions.
This new work by Dr. Gretchen North and colleagues, published in the December issue of American Journal of Botany (http://www.amjbot.org/cgi/reprint/ajb.1000286v1), sheds light on how one desert resident, the cactus Ariocarpus fissuratus, copes with the effects of high temperatures.
"One crucial point is that small desert plants such as the 'living rock' cactus occupy one of the hottest habitats on earth, the surface of desert soils" stated North.
Ariocarpus fissuratus earned its nickname "living rock" because it blends into the rocky surroundings with its small stature that is level with the soil's surface. The researchers hypothesized that the cactus could "escape" high temperatures by moving more of itself below the soil surface where it is cooler.
Measuring changes in plant depth and root anatomy, North and co-workers determined that the cactus moves deeper into the soil by contracting its roots. But does root contraction play a protective role by modulating temperatures?
To find out, the researchers mimicked summer desert conditions by growing plants on a rooftop in Los Angeles, where air temperature was above 99°F for several days. All the cacti were grown in sandy soil, but half had rocks covering the surface of the soil, similar to their native habitats. For plants grown in rocky soils, the internal temperature of the stem was about 39°F lower than those grown in sandy soils alone. While this may seem like a small decrease, it had a significant effect on the health of the plants.
Unlike the cacti grown in sandy soil which all died, those grown in rocky soil survived the intense heat. Root contraction aided in lowering the internal stem temperature, but only when combined with the cooling effects of the rocky surface. The opposite was true in sandy soil where cacti planted higher above the surface had slightly lower stem temperatures than those planted close to the surface.
"Even in rocky soil, experimental plants attained nearly lethal temperatures during a summer heat wave in Los Angeles" said North. "Thus, root contraction and rocky microhabitats may not provide enough protection should desert temperatures get much higher due to global warming.
CITATION: Tadao Y. Garrett, Cam-Van Huynh, and Gretchen B. North (2010). Root contraction helps protect the "living rock" cactus Ariocarpus fissuratus from lethal high temperatures when growing in rocky soil. American Journal of Botany 97(12): 1951-1960. DOI: 10.3732/ajb.1000286
The full article in the link mentioned is available for no charge for 30 days following the date of this summary at http://www.amjbot.org/cgi/reprint/ajb.1000286v1. After this date, reporters may contact Richard Hund at email@example.com for a copy of the article.
The Botanical Society of America (www.botany.org) is a non-profit membership society with a mission to promote botany, the field of basic science dealing with the study and inquiry into the form, function, development, diversity, reproduction, evolution, and uses of plants and their interactions within the biosphere. It has published the American Journal of Botany (www.amjbot.org) for nearly 100 years. In 2009, the Special Libraries Association named the American Journal of Botany one of the Top 10 Most Influential Journals of the Century in the field of Biology and Medicine.
For further information, please contact the AJB staff at firstname.lastname@example.org.
Richard Hund | EurekAlert!
Are there sustainable solutions in dealing with dwindling phosphorus resources?
16.10.2017 | Leibniz-Institut für Nutzierbiologie (FBN)
Strange undertakings: ant queens bury dead to prevent disease
13.10.2017 | Institute of Science and Technology Austria
Material defects in end products can quickly result in failures in many areas of industry, and have a massive impact on the safe use of their products. This is why, in the field of quality assurance, intelligent, nondestructive sensor systems play a key role. They allow testing components and parts in a rapid and cost-efficient manner without destroying the actual product or changing its surface. Experts from the Fraunhofer IZFP in Saarbrücken will be presenting two exhibits at the Blechexpo in Stuttgart from 7–10 November 2017 that allow fast, reliable, and automated characterization of materials and detection of defects (Hall 5, Booth 5306).
When quality testing uses time-consuming destructive test methods, it can result in enormous costs due to damaging or destroying the products. And given that...
Using a new cooling technique MPQ scientists succeed at observing collisions in a dense beam of cold and slow dipolar molecules.
How do chemical reactions proceed at extremely low temperatures? The answer requires the investigation of molecular samples that are cold, dense, and slow at...
Scientists from the Max Planck Institute of Quantum Optics, using high precision laser spectroscopy of atomic hydrogen, confirm the surprisingly small value of the proton radius determined from muonic hydrogen.
It was one of the breakthroughs of the year 2010: Laser spectroscopy of muonic hydrogen resulted in a value for the proton charge radius that was significantly...
It's possible to produce hydrogen to power fuel cells by extracting the gas from seawater, but the electricity required to do it makes the process costly. UCF...
Mercury, our smallest planetary neighbor, has very little to call an atmosphere, but it does have a strange weather pattern: morning micro-meteor showers.
Recent modeling along with previously published results from NASA's MESSENGER spacecraft -- short for Mercury Surface, Space Environment, Geochemistry and...
10.10.2017 | Event News
10.10.2017 | Event News
28.09.2017 | Event News
16.10.2017 | Physics and Astronomy
16.10.2017 | Earth Sciences
16.10.2017 | Physics and Astronomy