Duckweed

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Duckweed and its numerous applications.

  • Bioremediation
  • Aquaculture
  • Animal feed supplement
  • Environmental testing
  • Pharmaceuticals
  • Biofuels

International Conference on Duckweed!

http://duckweedresearch.blogspot.com/2011/11/presentations-of-1st-international.html

Aquatic plants, such as duckweed, grow near the surface of bodies of water, and tend to have a rather large volume relative to their weight, i.e., a relatively low density. However, duckweed can take on a variety of forms depending on many factors, including its life cycle stage, density and root length. In order to harvest the plant, a harvesting device must be suited to lift the duckweed in densities ranging from a thin “mono-layer” approximately 1/10 of an inch thick, to a 1″-4″ thick semi-solid mat of duckweed with the consistency of mud. In the “mono-layer” state, the duckweed disburses to fill gaps on the water surface. In the “semi-solid” state, the duckweed adheres to itself resisting separation.

Paper:  Journal (Water Pollution Control Federation)  Use of duckweed for waste treatment and animal feed: Dudley Culley

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How to grow duckweeds?

Growing duckweeds is like growing any other plant. Moderate conditions of temperature and light and a liquid medium with the necessary nutrients are essential for good growth.  Fortunately, duckweeds adapt well to a wide range of conditions and are easy to grow.

Duckweeds can be grown in the pond water from which they were collected in open containers.  It is important to replace the water frequently, since evaporation will result in concentration of salts.  Using open containers prevents overheating if you place the containers outside or in a sunny window.  See below for more about lighting duckweeds for the best growth.

In nature duckweeds grow in water from many sources and compositions.  They can be grown in artificial pond water or in diluted aquaculture media, such as Hoagland’s solution.  It is important to provide a source of chelated iron (included in the recommended synthetic media) and to adjust the pH to the optimal range.

It is important to keep your duckweed cultures clean. If you collect fresh duckweed specimens from nature, the water will contain a variety of other organisms.  These will include bacteria, fungi, algae, protozoa, and even small multicellular animals and insect larvae.  You can clean up your duckweed cultures by transferring the plants individually to clean fresh water.  Remove damaged and aged (yellow or white) fronds from your cultures as they appear.

Native populations of duckweeds may be mixtures with varying genetic compositions.  For serious work it is advisable to start cultures from a single clone.  This will help increase uniformity for experimental work.  It is easy to clone duckweeds.

 

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