Saving water in the vineyards

A water-saving Australian vineyard technology has been found to deliver a better glass of Shiraz or Cabernet Sauvignon.

In a win for the environment, grapegrowers, winemakers and wine drinkers, new research also shows that the enhanced colour and flavour in grapes grown using partial rootzone drying (PRD) do not come at the expense of high yield, says Professor Peter Dry of the Cooperative Research Centre for Viticulture.

"Accepted wisdom among grape growers has been that better colour had to mean smaller grapes," says Professor Dry. "This turns out not be the case with PRD.

"Research conducted by Keren Bindon for her PhD took a hard look at two important red wine varieties, Cabernet Sauvignon and Shiraz, being grown under [the] PRD system in two of South Australia's premier wine-growing areas, the Barossa Valley and Langhorne Creek," he says.

PRD applies water to just half of a vine's root system at a time, alternating the irrigation pattern every 3 to 10 days, on average, depending on the site characteristics. This means that half of the root system is in drying soil at any one time.

The vine reacts to the drying soil by allowing less water to escape through the pores on its leaves (stomata) which it normally uses to regulate its water use. At the same time, the water applied to the other half of the root system prevents the plant from becoming seriously 'water stressed'.

PRD was originally developed as a way to substantially reduce water use in the grape industry, says Prof Dry. The PRD process appears to cause a biochemical reaction in the fruit which leads to improved fruit aroma and flavour.

Researchers in different countries are testing PRD on a wider range of crops, including tomato, olive, cotton, stone fruit and citrus.