EVALUATION OF DIFFERENT COVERS USED IN GREENHOUSE CULTIVATION OF CAVENDISH BANANAS (MUSA ACUMINATE COLLA AAA) IN THE CANARY ISLANDS

From the 9,113 ha devoted to banana cultivation in the Canary Islands (CI) in 2008, 3,160 were under protected cultivation. Several types of covers with different thermic and optical characteristics are utilised in banana cultivation. The influence of 4 different covers [1) FPE, a clear polyethylene thermic cover of 860 gauges, a three-layer film, that sandwiches an expanded polymer layer with gas micro bubbles between two plain polymer layers, marketed commercially as Celloclim 4S^®, 2) M20, a monofilament mesh (20×10 threads cm^-2), 3) M16, another monofilament mesh 16×10 threads cm^-2 and 4) MB, a raffia mesh, marketed by Polysack^® as white net 50%] on growth, development and yield of the two most widely grown cultivars in CI ‘Grande Naine’ and ‘Gruesa’ were evaluated in field trials. The optical properties of these covers were also studied. The FPE cover presented better optical and thermic characteristics, such as low UV transmission and high (>75%) photosynthetic ally active radiation (PAR), and greater durability compared with previous covers utilised in CI under similar environmental conditions. The characteristics of M20 and M16 were found very similar, while MB reduced considerable PAR values (40-45%), which translated into an undesirable longer cycle length.