Nitrogen and water management implications on grape production in the Riverina wine grape regions in South Eastern Australia

Management of water and nitrogen is variable in the Riverina (NSW, Australia), being one of the major reasons yield and berry composition differ between Shiraz vineyards in this wine region. Both inputs can have a major impact on yield, canopy size and berry composition. Large canopies produced by excessive water and N supply result in shading of grapes and competition between vegetative and reproductive sinks of vines. The strategic application of water and N can be utilised to produce grapes and wines of higher quality and reduce the negative impacts on the environment. A field trial was conducted on a drip-irrigated Shiraz vineyard with three irrigation and three N treatments implemented. Partial rootzone drying (PRD) and regulated deficit irrigation (RDI) showed higher berry colour, but were less productive (vigour, yield) than the control (CTL). The water use efficiency (WUE) was improved by PRD and lowered by RDI. The N timing had little effect on vine productivity, but N applied in spring leads to higher juice amino N than juice from vines receiving the same amount of N after harvest. PRD vines produced the lowest amino N in the fruit.