Sap flow measurements in different young fig trees cultivars in Tenerife Island

The common fig, Ficus carica L., is a fruit deciduous tree widely spread in the temperate, subtropical and tropical zones and it is grown commercially under semiarid climatic conditions all around the Mediterranean basin. In the Canary Islands, increasing interest in figs as a valuable crop, makes necessary some studies on the behaviour of different cultivars under these particular environmental conditions. For this reason, in 2008, a new plantation with different fig cultivars was established in a semiarid zone in the south of Tenerife Island. All the cultivars were irrigated using drip irrigation with a restitution of 100% of crop evapotranspiration (ETc). We measured sap flow using the heat ratio method in four fig cultivars: 'Nazaret' (foreign San Pedro type), 'San Antonio' (foreign common type), 'Bicariña' (local common type) and 'Blanca Escalona' (local common type). Few studies had previously used the heat ratio method to measure sap flow in small saplings. However, heat ratio sap flow sensors captured well the diurnal and seasonal dynamics of transpiration, even providing estimations of nocturnal sap flow during nights with low relative humidity. The preliminary results showed a high variability between replications of the same cultivars, and although some differences in water use across varieties were observed, they were not statistically significant at this stage. Future analysis will require additional continuous meteorological data and leaf area measurements to assess cultivar-specific water use and its response to environmental variables.