Israeli researchers decipher self-watering mechanism of desert rhubarb 2009-07-02 02:50:36   Print

    JERUSALEM, July 1 (Xinhua) -- A group of Israeli researchers have mapped out the self-watering mechanism of desert rhubarb, which they say is able to harvest 16 times more water than other plants in the same environment and marks the first example of a self-irrigating plant worldwide.

    This desert plant was found growing in the mountains of the Negev desert in southern Israel, where the average precipitation is as low as 75 millimeters per year, according to a statement released Wednesday by the University of Haifa-Oranim.

    Unlike most of other desert plant species, which have small leaves so as to minimize moisture loss, this plant is unique in that its leaves are particularly large, and each plant's rosette of one to four leaves reaches a total diameter of up to one meter, said the statement.

    Researchers from the university noticed that its leaves are unusually large and covered with a waxy cuticle. They also observed an exceptionally ridged structure on each leaf, which forms a leaf structure resembling the habitat's mountainous topography.

    These deep and wide depressions in the leaves create a "channelling" mountain-like system, by which the rain water is channelled toward the ground surrounding the plant's deep root, explained the research team, while noting that other desert plants simply suffice with the rain water that penetrates the ground in its immediate surroundings.

    The findings show that the natural selection process has resulted in the evolution of this plant's extremely large leaves, which improve its ability to survive in the arid climate of the desert, said the statement.

    Experiments and analysis of the plant's growth in such an arid environment show that the desert rhubarb is able to harvest nearly as much water as Mediterranean plants do, namely up to 426 mm per year, which is 16 times the amount of water harvested by the small-leafed plants of the Negev desert region, added the statement.

    When the research team watered the plant artificially, they observed how the water flowed along the course of the leave's depressed veins to the ground surrounding the plant's single root and then penetrated the ground to a depth of 10 centimeters or more, said the statement, adding that under the experimental conditions, water normally penetrated the ground only as deep as 1centimeter.

    "We know of no other plant in the deserts of the world that functions in this manner," said the researchers in the statement.

Editor: Yan
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