Drought Resilience

Summary

Objective

The aim of this project is to develop management strategies to apply in irrigated, rain dependent vineyards during a drought to minimise the loss of yield and grape quality, through an understanding of vine and cover crop water use.

Background

For vineyards dependent on rainfall and supplementary irrigation, water security may not be sufficient to compensate for compounding seasonal rainfall deficits that accumulate during drought. As the difference between rainfall and potential evapotranspiration increases in the future even average seasonal conditions will have a higher demand for water than they do now. Canopy and floor management practices that specifically aim to modify the water supply and demand situation of a vineyard to make more of existing soil water may offer part of the solution to reducing future water risk without increasing reliance on irrigation.

Research approach

The work will build on a pilot study undertaken in the Orange region during the last two seasons, with instrumentation at three existing Shiraz monitoring sites expanded and the data used to validate the vineyard water balance model developed by Hochschule Geisenheim University for use in Australian vineyards. Soil coring and molecular methods will be used to characterise the relative distribution of grapevine roots and those of the resident mid-row and undervine plant cover. The relative share of plant available soil water as influenced by floor management practices and soil conditions will then be quantified.

In parallel, a replicated field plot study will establish crop coefficients of selected cover crop species, and a pot study will screen for possible variation in isohydric vs. anisohydric type responses to water stress as a trait to consider in matching to grapevine varieties. Through a modelling approach, management strategies to better follow seasonal water availability will then be proposed, and the implications of cover crop water use traits for water competition and longer-term vineyard water use efficiency will be tested.

Sector benefits

The project will use modelling and direct measurement to provide grapegrowers with an understanding of the water use of a selection of groundcovers (commercial pastures species and native grasses) in a range of vineyard soil moisture scenarios. This knowledge can be used to develop strategies for making the most effective use of available water (rain and irrigation) and for reducing drought risk.