PROCESO DE ENVEJECIMIENTO NATURAL DE UNA PELÍCULA UTILIZABLE COMO MATERIAL DE CUBIERTA DE INVERNADEROS

Abstract

In the present communication it is presented a procedure to determine the aging of a (plastic) film used as cover material for greenhouses. For this purpose, both the PAR (Photosynthesis Active Radiation) and the global radiations were followed continuously, inside and outside, the greenhouse during three periods. Besides this, samples have been considered for different structural positions and the traction strengths have been determined by testing the sampled materials. Variance analysis method and test of minimum significance differences have been applied to these results. The present study allows conclude that the film shows a considerable increase of the absorbed radiation at the second year of use. Taking into account that this radiation is the active for the photosynthesis process, it is deduced that the useful life of this film is two years. It is also observed a spatial variability very accused between the position of the tested sample and the traction strength and elongation at the fluency point. These tests have been useful to develop a model based on the squared minimum method to adjust the data considering both kind of radiations (PAR and global).