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