Biodegradable pots for Poinsettia cultivation: Agronomic and technical traits

A large quantity of plastics is utilized by floriculture and especially for the production of flowering potted plants, where the pot is a very important component of the whole marketable product. Among these, poinsettia (Euphorbia pulcherrima Willd. ex Klotzsch) is a typical example of ornamental potted-plant characterized to have a relatively long crop cycle, a strong demand, especially in Europe and North America, concentrated in the Christmas period and a short shield life. Its cultivation produces a huge quantity of plastic pots to be managed in the right way to avoid environmental risks. A solution of this problem could be the use of biodegradable pots instead of traditional ones. Nevertheless, it is necessary to verify if these materials, although having biodegradability properties, are able to ensure comparative levels of technical use as traditional plastic materials. In this paper, three different kinds of biodegradable pots (biodegradable polyester, plain or added with plant fibers) plus a traditional one (polypropylene, PP) were tested in two cultivation cycles of poinsettia (E. pulcherrima cv Premium red). The trial was carried out in a heated greenhouse located in Southern Italy (40 degrees 38'N; 14 degrees 55'E; 50 m a.s.l.). Agronomical response of plants as well as the mechanical and colorimetric behavior of pots over time were studied. Result have shown that poinsettias growth in pots charged with plant fiber have had good values of some agronomical qualitative and quantitative indexes. Mechanical tests have pointed out that pots made by 100% biodegradable polyesters have a good mechanical resistance, with a decrease of the maximum tensile strength (sigma(max)) of just 32.2% during the trial, and a fixed color over time. Pots made of biodegradable polyesters variously added with plant fibers do not seem appropriate for poinsettia cultivation especially for the fast falling of the sigma(max) that, in the case of the biodegradable pot added with 20% of plant fibers, that decreased of 81.3% during the trial. (C) 2015 Elsevier B.V. All rights reserved.