Experiences of defict irrigation strategies on young orange trees: effects on physiological response and fruit quality

In reason of the general decline of water resources for the agricultural sector, worldwide attention is focused onstrategies optimizing water resources, by reducing losses and defining more efficient water allocations duringwater scarce periods or droughts; it is the case of Deficit Irrigation (DI) strategies. In particular, Regulated DIcriteria are, generally, able to improve water productivity and reduce irrigation volumes by imposing waterdeficits on crops during noncritical growth periods. The success of DI strategies depends on water stressmanagement, i.e. the timing and severity of the applied water stress. In this sense, methods that monitor plantstress indicators are needed when DI strategies are applied. The study herein proposed reports the application ofDI strategies on young orange orchards [Citrus sinensis (L) Osbeck] cv ‘Tarocco Sciara’ C 1882 grafted onCarrizo citrange (Citrus sinensis Osb. x Poncirus trifoliata Raf.), during 2010-2011 years in Sicily.Physiological and agronomic responses of the young orange trees to DI strategies were investigated during thetrials. To assess the usefulness for plant water status detection, indicators such as canopy temperature, stemwater potential, stomatal conductance, changes in vapour pressure deficit (VPD) were analysed. Results showedthat water savings achieved in the most stressed treatments, irrigated at 50% of crop evapotraspiration duringsummer, have slightly impaired plant vegetation growth. Canopy temperature (Tc, °C) results a reasonablequantitative water stress parameter for the studied plant. In fact, as suggested by several recent applied studies,continuous measurements of Tc could be a useful tool for scheduling deficit irrigation.