Interactive effects of irrigation method, irrigation amount, and fertilization rate on yield, water productivity, and berry and wine quality of Marselan (Vitis vinifera L.) in an arid region

Water scarcity and inefficient nutrient use constrain viticulture in arid regions, necessitating irrigation–fertilization strategies that balance productivity, resource-use efficiency, and grape and wine quality. This two-year field study evaluated alternate partial root-zone irrigation (APRI) and regulated deficit irrigation (RDI) combined with three irrigation amounts (IA; W100, W75, and W50, corresponding to 100%, 75%, and 50% of full irrigation, respectively) and two fertilization amounts (FA; F100 and F50, corresponding to 100% and 50% of the standard fertilization rate, respectively) in Marselan grapevines. IA was the most consistent factor influencing productivity and resource-use efficiency. Full irrigation generally favored yield, whereas reduced irrigation increased irrigation water-use efficiency (IWUE), with APRI-W50F50 achieving the highest IWUE in both seasons. Berry physical attributes showed limited responses to the main factors, whereas berry ripening and phenolic composition were more responsive to resource supply and factor interactions. Wine physicochemical properties, phenolic composition, color, and sensory profiles were strongly affected by vintage and irrigation–fertilization interactions. Multivariate analyses revealed substantial treatment- and vintage-related phenolic variation, while orthogonal partial least-squares discriminant analysis (OPLS-DA) identified compositional patterns associated with irrigation method (APRI vs. RDI) in both grapes and wines. However, neither irrigation method consistently enhanced phenolic accumulation or wine quality across vintages. No single treatment simultaneously optimized productivity, resource-use efficiency, and grape and wine quality. These findings highlight the need for integrated, target-oriented management of irrigation method, water supply, and fertilization rather than the independent selection of APRI or RDI.