Growth Characteristics and Proximate Profile of Duckweed (Lemna minor) Cultured in Calabar – Humid Zone of Nigeria

Abstract

A twenty-day growth trial was conducted to evaluate the growth characteristics
and proximate composition of duckweed (Lemna minor) cultured in a concrete pond
(33,975.43 litres) with a pond depth of 40cm and dilution of 25% piggery effluent.
Observation revealed that biomass increase occurred every day. Harvesting was carried out
every four days for five times successfully and total yield was 14.72 kg. The growth of
duckweed harvested and that obtained from a natural pond were sun-dried and
representative samples taken for proximate analysis. The proximate composition of the two
samples were compared, the results obtained showed that the grown duckweed contained
crude protein (42%), crude fibre (28%), ether extract (1.5%), ash (8%) and nitrogen free
extract (10.5%) fractions; while the duckweed from the natural pond had crude protein
(21.87%), crude fibre (20%), ether extract (1%), ash (11%) and nitrogen free extract
(46.13%), respectively. The proximate composition of the cultured duckweed appeared
higher in all fractions beside the nitrogen free extract. However, irrespective of the
medium where the duckweed was harvested, the crude protein value obtained suggested
that duckweed can be incorporated into livestock feeds as a protein supplement,
particularly when grown on nutrient rich mediums