Plastic films and soil management interaction on organic ‘Sugrathirteen’® table grapes quality in Apulia region

In order to advance or delay grape ripening, colored covering plastic films with different radiometric properties are often used in table grape viticulture in South Italy. Covering films protect also clusters from adverse weather conditions, such as rain, hail and wind, and reduce damage of the berries from diseases, especially in organic viticulture. The covering of vineyards is a sustainable choice for the organic soil management strategies that will influence also grape quality and quantity. This paper presents the results obtained during an experimental test carried out during 2012 at an organic irrigated 'Sugrathirteen'® table grape vines cultivation at Gioia del Colle (Bari, Italy). Three plastic films, coded Yellow, Neutral and Red film, were used to cover the grapes. Three different soil inter-row space management, such as tilled cultivation, permanent resident cover crop and temporary sub-terranean clover, were applied. The interaction effects of the plastic films and of the soil inter-row space management were analysed. Radiometric tests were carried out in laboratory on the plastic films at the beginning of the vegetation period. Different soil management strategies and plastic films covering have shown high interaction on vines water status in relation to midday stem water potential during berry growth period. Berry weight was affected from plastic film∗soil management interactions with a highest berry mass on Yellow plastic film∗Trifolium soil management. An high interactions between different soil managements∗plastic films were observed in terms of T.S.S., T.A. and pH, with the highest sugar accumulation on berries under Yellow plastic film∗Trifolium soil treatment. In conclusion a temporary cover crop with sub clover or resident vegetation under Yellow plastic film seems to improve table grape performance with clear effects on quality berry parameters.