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Mestrado em Engenharia do Ambiente - Instituto Superior de Agronomia Due to the large amount of mulch films used in agricultural crops and to all the environmental problems related with their disposal, the biodegradable mulch films seems to be the best solution for replacing the conventional polyethylene mulches. The main goal of this work was to evaluate and compare the performance of biodegradable mulch films with the conventional polyethylene ones in muskmelon culture during two years. Beyond fruit productivity and quality, the impact of each plastic in the soil moisture and temperature were also assessed. Taking into account that there are no reported biodegradation studies realized in Portugal, it was also important to verify the biodegradability of this new mulch films under the Portuguese soil conditions. The biodegradable mulch films did not show significant differences in fruit productivity and quality. The biodegradation rate of the mulches tested was not as high as would be expected. From the overall results obtained, biodegradable mulch films appear to be a good solution for the replacement of the conventional polyethylene mulches, however the R&D should continue to be done to improve their biodegradation rate.

The development of conventional mulch films made from polyethylene (PE) really enhanced the commercial production of horticultural systems. However its utilisation derives significant environmental impacts due to the problems associated with its management at the end of the crop cycle. The process of PE removal always produces small fragments, caused by structural fragility at the end of the crop cycle, due to continued exposure to environmental conditions. A solution to reduce the environmental impacts related with this practice should include the development of economically competitive biodegradable plastics, which at the end of the campaign can be plough into the soil to naturally degrade there. The aim of this study was to compare the field performance of a biodegradable mulch film (agrobiofilm) against PE, in the production of strawberry (Fragaria x ananassa Duch.) during the autumn production cycle, both in greenhouses and open field conditions. The field trial was established in a 715m2 plot in Azeitada (Portugal). Three completely randomised blocks of 25 plants per mulch were selected, on which some parameters such as temperature and soil moisture, productivity and fruit quality were evaluated. The results obtained in greenhouse and open field conditions, as regards the quality of the fruits, do not reveal any significant differences. Regarding the fruit yield there were significant differences only in greenhouse production, with agrobiofilm showing a higher fruit yield (35,2 tons/ha) compared to PE (31,0 ton/ha). Soil probes showed that to a depth of 20cm the temperature was on average 1ºC higher under PE mulch. However, at 30cm the soil conditions changed, being 1ºC higher under agrobiofilm. During the first year of AGROBIOFILM project, the tested biodegradable mulch film showed to be a sustainable option to the replacement of PE based mulches, since it finely adapted to the climatic conditions and conventional agricultural practices