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 pottedplants, 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-plantcharacterized to have a relatively long crop cycle, a strong demand, especially in Europe and NorthAmerica, concentrated in the Christmas period and a short shield life. Its cultivation produces a hugequantity of plastic pots to be managed in the right way to avoid environmental risks. A solution of thisproblem could be the use of biodegradable pots instead of traditional ones. Nevertheless, it is necessaryto verify if these materials, although having biodegradability properties, are able to ensure comparativelevels of technical use as traditional plastic materials.In this paper, three different kinds of biodegradable pots (biodegradable polyester, plain or added withplant 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◦38°N; 14◦55°E; 50 m a.s.l.). Agronomical response of plants as well as the mechanical and colorimetricbehavior of pots over time were studied.Result have shown that poinsettias growth in pots charged with plant fiber have had good valuesof some agronomical qualitative and quantitative indexes. Mechanical tests have pointed out that potsmade by 100% biodegradable polyesters have a good mechanical resistance, with a decrease of the max-imum tensile strength (Sigma max) of just 32.2% during the trial, and a fixed color over time. Pots made ofbiodegradable polyesters variously added with plant fibers do not seem appropriate for poinsettia culti-vation especially for the fast falling of the maxthat, in the case of the biodegradable pot added with 20%of plant fibers, that decreased of 81.3% during the trial.