Guttation is the appearance of drops of
xylemsap on the tips or edges of leaves of some vascular plants, such as grasses.
transpirationusually does not occur because most plants have their stomataclosed. When there is a high soil moisturelevel, water will enter plant roots, because the water potentialof the roots is lower than in the soil solution. The water will accumulate in the plant creating a slight root pressure. The root pressure forces some water to exude through special leaftip or edge structures, hydathodes, forming drops. Root pressure provides the impetus for this flow, rather than transpirational pull.
Guttation fluid may contain a variety of organic compounds, mainly sugars, and mineral nutrients, and potassium. [cite journal | last = Goatley | first = James L. | authorlink = | coauthors = Lewis, Ralph W. | title = Composition of Guttation Fluid from Rye, Wheat, and Barley Seedlings | journal = Plant Physiology | volume = 41 | issue = 3 | pages = 373–375 | publisher = | date = March 1966 | url = http://www.pubmedcentral.gov/articlerender.fcgi?tool=pmcentrez&artid=1086351 | doi = | id = | accessdate = 2006-10-31 | pmid = 16656266] On drying, a white crust remains on the leaf surface.
If high levels of nitrogen appear in the fluid, then that is a sign of
fertilizer burn. Excess nitrogen must be leached from the soil by addition of large quantities of water. This may result in water pollution, but is the best way to restore soil fertility. [ [http://www.improve-your-garden-soil.com/fertilizer-burn.html Avoiding Fertilizer Burn ] ]
Guttation is not to be confused with
dew, which condenses from the atmosphere onto the plant surface.
Soil plant atmosphere continuum
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