Archives of plant science blog

April 4, 2006, 11:13 PM CT

Does tropical biodiversity increase during global warming?

STRI's Carlos Jaramillo and colleagues Milton J. Rueda and Germán Mora, seek explanations for the longest Central and South America pollen record, published in today's issue of Science

"Plant diversity seems to increase when tropical forests cover large areas. Shrinking ecosystems may experience biodiversity loss lasting for millions of years." STRI's Carlos Jaramillo and his colleagues Milton J. Rueda from the Colombian Petroleum Institute and Germán Mora, from Iowa State University, seek explanations for the longest Central and South America pollen record, published in today's issue of Science.

Jaramillo et al. used cores drilled through 5km of rock in eastern Colombia and western Venezuela to get at the fossil pollen record in a sequence of samples representing 10 to 82 million years before present (mybp). Then they correlated pollen diversity with global temperature estimates for the middle part of that sequence (20-65 mybp).

"We found that pollen diversity tracks global temperature through time over millions of years. Diversity increases as the planet warms and decreases as it cools. The mystery is that even when global temperatures vary enormously, average temperatures in the tropics don't change much, so why do we see global temperature patterns reflected in tropical plant diversity?" Jaramillo proposes that changes in area drive speciation and extinction in the tropics.

During global warming, tropical areas expand and diversity goes up, the opposite happens during global cooling. If this is the case, fragmentation of modern tropical forest could be equated to a global cooling period, because forested areas are shrinking dramatically, resulting in plummeting diversity in the forests that remain".........

Posted by: Erica Permalink Source

April 1, 2006, 9:01 AM CT

Why tipsy flowers don't tip over

From left: Untreated paperwhites grown in water, then plants grown in 2 percent, 4 percent, 6 percent, 8 percent and 10 percent ethanol.

Those paperwhites and other daffodils sure could use a drink -- a little whiskey, vodka gin or tequila could keep them from falling over.

A new Cornell study finds that a touch of booze is a great way to keep certain houseplants from getting too tall by stunting their growth. "Dilute solutions of alcohol -- though not beer or wine -- are a simple and effective way to reduce stem and leaf growth," said William Miller, professor of horticulture and director of the Flower Bulb Research Program at Cornell.

"When the liquor is properly used, the paperwhites we tested were stunted by 30 to 50 percent, but their flowers were as large, fragrant and long-lasting as usual," added Miller, whose new study on how alcohol inhibits houseplant growth would be reported in the recent issue of HortTechnology, a peer-reviewed journal of horticulture.

Miller will be working this spring to see if a little booze works for amaryllis and such vegetables as tomatoes and peppers, as well. His work with tulips so far has been promising but still not definitive: "I think with a little jiggering -- no pun intended -- of the system, the method will work for tulips, though I think it will not be as simple as with paperwhites."

Last year, Miller received a call from The New York Times about a reader who had written to the garden editor claiming that gin had prevented some paperwhite narcissi from growing too tall and floppy and asked if it was because of some "essential oil" in the gin.........

Posted by: Erica Permalink Source

March 29, 2006, 10:40 PM CT

Ocean 'dead zones' posing extinction threat

Dead zones are occurring in many areas along the coasts of major continents, and they are spreading over larger areas of the sea floor. Because very few organisms can tolerate the lack of oxygen in these areas, they can destroy the habitat in which numerous organisms make their home.

Oxygen depletion in the world's oceans, primarily caused by agricultural run-off and pollution, could spark the development of far more male fish than female, thereby threatening some species with extinction, according to a study published recently on the Web site of the American Chemical Society journal, Environmental Science & Technology. The study is scheduled to appear in the May 1 print issue of the journal.

The finding, by Rudolf Wu, Ph.D., and colleagues at the City University of Hong Kong, raises new concerns about vast areas of the world's oceans, known as "dead zones," that lack sufficient oxygen to sustain most sea life. Fish and other creatures trapped in these zones often die. Those that escape may be more vulnerable to predators and other stresses. This new study, Wu says, suggests these zones potentially pose a third threat to these species - an inability of their offspring to find mates and reproduce.

The researchers found that low levels of dissolved oxygen, also known as hypoxia, can induce sex changes in embryonic fish, leading to an overabundance of males. As these predominately male fish mature, it is unlikely they will be able to reproduce in sufficient numbers to maintain sustainable populations, Wu says. Low oxygen levels also might reduce the quantity and quality of the eggs produced by female fish, diminishing their fertility, he adds.........

Posted by: Kelly Permalink Source

March 25, 2006, 10:45 AM CT

Tastier Tomatoes In Making?

Tomatoes are a major nutrient for humans. In 2004, 120,000 tonnes of tomatoes were harvested worldwide - and every year this number increases. Numerous medical studies have shown the health value of tomatoes. Lycopen, the pigment that makes tomatoes red, can for example prevent heart disease. Tomatoes furthermore contain a lot of vitamins C and E, indispensable for human nourishment. But after centuries of cultivation for shape, colour, and other useful qualities, our cultured tomatoes today are of small genetic diversity, in comparison with wild types. This has affected the taste and health value of the fruits.

To cultivate tomato strains with particular characteristics, scientists have to increase the genetic diversity of cultured tomatoes. This can be done either by cross-breeding them with wild tomatoes, or changing their genetic make-up technologically. Researchers from the Max Planck Institute for Molecular Plant Physiology in Golm, and their Israeli colleagues at Hebrew University in Jerusalem, chose the second option. They investigated strains of tomatoes created from the crossing of cultured and wild types. Their goal was to identify the biochemical composition of fruits and determine which factors control their development. The German-Israeli research team used a method of analysis developed at the Max Planck Institute for Molecular Plant Physiology. The technique - a combination of mass spectrometry and gas chromatography - analyzes the composition of biological samples. It can be used to quickly and simultaneously look into a fruit's amino acids, organic acids, sugar and vitamins.........

Posted by: Erica Permalink Source

March 21, 2006, 10:13 PM CT

Amazon Rainforest Greens Up

The green color in this image of South America shows vegetation that is growing during during the dry season.

The Amazon rainforest puts on its biggest growth spurt during the dry season, as per new research.

The finding surprised the researchers.

"Most of the vegetation around the world follows a general pattern in which plants get green and lush during the rainy season and then during the dry season, leaves fall because there's not enough water in the soil to support plant growth," said lead researcher Alfredo R. Huete of The University of Arizona in Tucson.

"What we found for a large section of the Amazon is the opposite. As soon as the rains stop and you start to enter a dry period, the Amazon becomes alive. New leaves spring out, there's a flush of green growth and the greening continues as the dry season progresses."

The finding holds true only for the undisturbed portion of the rainforest. Areas where the primary forest has been converted to other uses or disturbed, "brown down" in the dry season, said Huete, a UA professor of soil, water and environmental science.

Huete suggests the deep roots of trees in the undisturbed forest can reach water even in the dry season, allowing the trees to flourish during the sunnier, drier part of the year. In contrast, plants in areas that have been logged or converted to other uses cannot reach deep water in the dry season and therefore either go dormant or die.........

Posted by: Erica Permalink Source

March 19, 2006, 8:56 PM CT

How to Plant an Avocado Tree

The next time you eat an avocado or use one in a recipe, save the pit. Planting your own avocado tree is fun and easy!.

Cut into your carefully so as not to injure the pit located in the fruit's center. Carefully remove the pit and set it aside. Use the avocado meat to create the tasty dip/topping known as guacamole.

Gently wash the avocado pit, removing all avocado flesh from the pit.

Holding the pit "narrow" (pointed) side up, stick four toothpicks into the middle section of the pit at even intervals, to a depth of about 1/8-inch.

In a small, slender container (preferably glass), add water until it reaches the very top rim. Your container's opening should be wide enough to easily accommodate the full width of the avocado, but not too much wider.

Set your avocado pit (with inserted toothpicks) on the top rim of the container. The toothpicks should sit on the rim of the container, while keeping the pit only half-submerged in the water.

Set the avocado-topped container in temperate, undisturbed place--near a window or other well-lit area--to begin the rooting and growth process.

Change the water every 1-2 days to ensure that contaminants (i.e. mold, bacteria, fermentation, etc.) do not hinder the avocado sprouting process. Ensure that the base of the avocado always remains moist and submerged in water.

Posted by: Erica

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March 19, 2006, 8:50 PM CT