Deficit irrigation strategies in grapevine (Vitis vinifera L.). Ecophysiologic responses, growth-yield balance, canopy and cluster microclimate for improving quality under mediterranean climate. Tesi di dottorato

The main objective of this study was to analyse, in Mediterranean climate areas, the effects of drip-irrigation strategies on field-grown grapevine ecophysiology, vegetative growth and yield, as well as on canopy and cluster microclimate, to improve quality without compromising productivity or vine life-time. Three irrigation trials were established: the first during 2008-2009, in a ‘Cannonau’ vineyard of Nurra wine region (Alghero, North-Western Sardinia); the second was conducted in 2009-2010, in a ‘Vermentino’ vineyard of Parteolla wine region (Serdiana, South Sardinia); the third trial was established in 2011 in a ‘Vermentino’ vineyard of Nurra wine region. Full (FI), classic deficit (DI) and partial root-zone drying (PRD) irrigation strategies were set after fruit-set until harvest. Two irrigation scheduling methods were tested. The first was based on maximum evapotranspiration estimation (ETm) and replenishment of ETm fractions, using DI or PRD strategies. In ‘Cannonau’ trial, four treatments were set: FI100, DI50, DI25 (supplying 100%, 50% and 25% of ETm) and PRD (50% ETm to one side of the root system, allowing the other side to dry, alternating the watered side every 15 days); in ‘Vermentino’ Parteolla trial the treatments were: DI80, DI40, PRD80, PRD40. In Vermentino’ Nurra trial, irrigation was set according to stem water potential. Four irrigation treatments were tested: early deficit (ED), late deficit (LD), irrigated control (IC) and non irrigated control (NC).