Effects of solar radiation on the radiometric properties of biodegradable films for agricultural applications

Research was carried out in order to evaluate the modifications of the radiometric properties of innovative biodegradable films exposed to the climatic agents. The biodegradable materials were used for crop protection in the cultivation of strawberry plants in Southern Italy during the winter and spring seasons. Low tunnels were covered using four different transparent biodegradable films. Climatic data of the site and microclimatic parameters inside the low tunnels were measured during the cultivation period. Laboratory tests were carried out on the samples of films gathered during the field trial in order to evaluate the effects of the solar radiation on the radiometric characteristics. A decrease of up to 13% of the transmissivity in the photosynthetically active radiation range was identified for the materials exposed during the field trial. The variation of the radiometric properties, as a function of the cumulative solar radiation falling on the covering material, showed that the reduction of the transmissivity coefficient in the photosynthetically active radiation range occurred mainly up to 500 MJ m(-2) of cumulative solar radiation, corresponding to 10% of the yearly local value. Besides equations relating the photosynthetically active radiation transmissivity coefficient and the cumulative solar radiation were defined by means of linear regression processed on the experimental data. (C) 2004 Silsoe Research Institute. All rights reserved Published by Elsevier Ltd.