Chitin is a natural polysaccharide, which consists of a
copolymer of N-acetyl-D-glucosamine and D-glucosamine
residues, linked by b-1,4 glycosidic bonds. It is present in a
variety of species: in shells of crustaceans, in cuticles of insects
and in the cell wall of fungi and some algae. The deacetylated
form of chitin is chitosan. The chitosan biopolymer has
applications in waste water treatment, pulp and paper, in
medical and cosmetic products, biotechnology, food and feed
and membranes [1]. In agriculture, chitosan has been used in
seed, leaf, fruit and vegetable coating [2], as fertilizer and in
controlled agrochemical release [3], to increase plant product
[4–6], to stimulate the immunity of plants [7], to protect plants
against microorganisms [8–10] and to stimulate plant growth.
In the latter studies, a positive effect of chitosan was observed
on the growth of roots, shoots and leaves of various plants
including Gerbera [4] and of several crop plants [11]. Orchid
roots sprayed with a very diluted chitosan solution show