Lemna

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iDuckweed

Common Duckweed (Lemna minor)

Scientific classification

Kingdom:	Plantae
Division:	Magnoliophyta
Class:	Liliopsida
Order:	Alismatales
Family:	Araceae
Genus:	Lemna L.

Species

Lemna gibba : Gibbous Duckweed
Lemna minuta
Lemna minor : Common Duckweed
Lemna trisulca : Ivy Duckweed

Lemna is a genus of free-floating aquatic plants from the duckweed family. The duckweeds have been classified as a separate family, the Lemnaceae, but some researchers (the AGP II) consider the duckweeds members of the Araceae.

Lemna species grow as simple free-floating thalli on or just beneath the water surface. Most are small, not exceeding 5 mm in length, except Lemna trisulca which is elongated and has a branched structure. Lemna thalli have a single root, which distinguishes them from related species Spirodela and Landoltia

The plants grow mainly by vegetative reproduction, two daughter plants bud off from the adult plant. This form of growth allows very rapid colonisation of new water. Duckweeds are flowering plants, and nearly all of them are known to reproduce sexually, flowering and producing seed under appropriate conditions. Certain duckweeds (e.g. L. gibba) are long day plants, while others (e.g. L. minor) are short day plants.

When Lemna invades a waterway, it can be removed mechanically, by the addition of herbivorous fish (e.g. grass carp) or treated with a herbicide.

The rapid growth of duckweeds finds application in bioremediation of polluted waters and as test organisms for environmental studies. It is also being used as an expression system for economical production of complex biopharmaceuticals.

Nutritional Value(dry matter)

Protein 25% Fat 4.4% Fibre 8-10% Under scientific farming with fertilisers the protein content can be increased to 45% Duckweed meal(dried duckweed) is a good cattle feed,

Scientific Farming

Eventhough duckweed can tolerate the temperature of 6 degree Celsius to 33 degree Celsius,the appropriate temperature range for a good harvest is 20 degree Celsius to 28 degree Celsius. PH 5to9,better growth is possible in a PH range of 6.5 to 7.5.A minimum water depth of 1' is required .To attain a protein content of 45% ,the soluble Nitrogen in the water should be 60Mg/Litre and the Phosphorus 1Mg/Litre,,for the requrement of micronutrients put crude common salt ,fertilser is required on a daily basis.We can farm the Duckweed organically,cattle dung Pig waste biogas plant slurry,or any other organic matter can be fed to the farm in a slurry form.Harvesting should be done on a daily basis otherwise the fast growing weed will fill the pool and will depress the further growth.after the harvest assure that there is only less than a kilogramm of weed is there in a squaremeter.We can expect a yield of 20-40 Tons of dried Duckweed from a hectare of farm,that is 9-18 Tons of Potein.

[edit] References

Cross, J.W. (2006). The Charms of Duckweed.
Landolt, E. (1986) Biosystematic investigations in the family of duckweeds (Lemnaceae). Vol. 2. The family of Lemnaceae - A monographic study. Part 1 of the monograph: Morphology; karyology; ecology; geographic distribution; systematic position; nomenclature; descriptions. Veröff. Geobot. Inst., Stiftung Rübel, ETH, Zurich.
Lemna Ecotox testing Duckweed growth inhibition tests and standardisation