Responses of 'Syrah' grapevine to deficit irrigation in the Brazilian semi-arid region

Abstract

Grapevine growing in areas with low rainfall as the Brazilian semi-arid requires irrigation to full fill plant water demand. The objective of this study was to evaluate the physiological and yield responses of grapevine to irrigation strategies in the Lower Middle São Francisco Valley, in Petrolina, State of Pernambuco, Brazil. The experiment was carried out over three consecutive growing seasons of drip irrigated 'Syrah' grapevine, grafted on 1103 Paulsen and planted in an Ultisol (Soil Taxonomy, USA). Full irrigation (FI), regulated deficit irrigation (RDI), and deficit irrigation (DI) treatments were designed in a randomized block with four replications. Mostly soil moisture depletion was observed until 0.6 m soil depth while higher moisture values and their small variation over the time were observed below 0.6 m and until 1.20 m depth as consequence of dense soil layers. RDI and DI promoted moderate water stress in plants (pre-dawn water potential from −0.2 to 0.4 MPa), reducing water consumption and gas exchange. Intrinsic water use efficiency was higher in RDI and DI (121 and 115 µmol CO2 mol H20−1, respectively). Tritratable acidity reduced to 5.81 and 6.28 g L−1 tartaric acid as water deficit increased, except in the third season. Soluble solids were influenced by treatments only in the second season, when it decreased in FI plants (22.6° brix). Weight of 100 berries was influenced by treatments in all seasons, with lower values for DI and RDI grapevines (less than 155 g). Number (15) and weight (2.2 kg) of cluster per grapevine and yield (7284 kg) were significantly higher in FI only in the third growing season, while average cluster weight was greater in FI in the first and third seasons (84 and 149 g, respectively). Irrigation water productivity did not differ among irrigation strategies. Deficit irrigation strategies allowed water saving.