Question

what type of growth do duckweed plants display?

Answer 1

Duckweed species are small floating aquatic plants found worldwide and often seen growing in thick, blanket-like mats on still or slow moving, nutrient-rich fresh or brackish waters. They are monocotyledons of the botanical family Lemnaceae and are higher plants or macrophytes, although they are often mistaken for algae.

Duckweeds grow at water temperatures between 6 and 33°C.

The natural habitat of duckweed is the surface of fresh or brackish water which is sheltered from wind and wave action. They do not survive in fast moving water (>0.3 m/second) or water unsheltered from wind which is an important attribute as they do not become weeds in water ways.

The best nutritional situations for duckweed growth are in waters with decaying organic material, providing it with a steady supply of nutrients. A dense cover of duckweed inhibits competing submerged aquatic plants, which require solar energy for growth and they can also often exclude algae from bodies of water.

Unlike most plants, duckweed tolerates relatively high concentrations of salts (up to 4000 mg/litre total dissolved solids).

Duckweed survives from pH 5 to 9, but grows best over the pH 6.5 to 7.5 range. Ammonia, in the ionised form is the preferred N substrate for duckweed. free ammonia is toxic to duckweed at high concentrations (>100 mg NH3/litre).

The nitrogen content, however, seems to increase over the range from trace ammonia concentrations to 7-12 mg N/litre when the N x 6.25 is maximised at around 40% Urea is a suitable fertiliser which is rapidly converted to ammonia under normal conditions.

When effectively managed in this way duckweeds yield 10-30 ton DM/ha/year containing up to 43% crude protein, 5% lipids and a highly digestible dry matter.