Introductory Crop Physiology

Guttation

In some plants such as tomato and colocasia, water drops ooze out from the uninjured margins of the leaves where a main vein ends. This is called as guttation and takes place usually early in the morning when the rate of absorption and root pressure are high while the transpiration is very low.

• The phenomenon of guttation is associated with the presence of special types of cellsat the margins of the leaves which are called as water stomata or hydathodes.
• Each hydathode consists of a water pore that remains permanently open.
• Below this, there is a small cavity followed by a loose tissue called as epithem.
• This epithem is in close association with the ends of the vascular elements of veins.
• Under high root pressure, the water is given to the epithem by the xylem of the veins and from epithem, water is released into the cavity.
• When this cavity is completely filled with watery solution, it begins to ooze out in the form of watery drops through the water pore.






Courtesy: 1.http://www.studentsguide.in. 2. http://www.bio.miami.edu

Under higher root pressure, water is given to the epithem by the xylem of the veins. From epithem, the water is released into the cavity. When this cavity is completely filled with the watery solution, the latter begins to ooze out in the form of watery drops through the water pore.

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