VSIM model adaption to Qualified Denomination of Origin Rioja soil and weather conditions

Resumen

Irrigation is a key practice for wine grapes production. Both, irrigation in excess and lack of irrigation could producedifferent wine faults. Traditionally, vineyard irrigation was considered as a way to increase yield although it reducedproduct quality. The aim of this research was to adapt VSIM model to weather and soil conditions of QualifiedDesignation of Origin Rioja in northeast Spain. Plots were planted mainly with Tempranillo cultivar, althoughGraciano, Tempranillo Blanco and Viura were also grown in three plots. Humidity sensors were placed at two depths toassess plant response to water stress. In addition, one weather station was set in each plot and data was transmitted inreal time through a host control platform enabling data browsing by wineries technicians and researchers. Grapesamples were analyzed during harvest to supplement in real time data. Two treatments were applied: irrigation based onadapted VSIM model and rainfed. Each monitoring system test weekly water balance relating those data with waterstatus of each plant by dendrometry measurements. Adaptations of VSIM model to Rioja soil and weather conditionsreplaced Leaf Area Index (LAI) by Normalized Difference Vegetation Index (NVDI) along with trunk diametermeasurements using dendrometry. Furthermore, crop coefficient was calculated based on NVDI instead of LAI andwater stress thresholds were modified from originals. The main problem was to define a desired water stress to obtainan adequate yield without reducing fruit quality, although dendrometry measurements helped to check if the plant sufferor not water stress. In conclusion, adapted VSIM model contributed to optimize water resources through measuring soilhumidity, grapevine growing and trunk diameter through dendrometry.