Performance of vines under reduced irrigation: Development of cost-effective irrigation scheduling tools

Abstract

The aim of this project was to take one step further the assessment of plant-based tools resulting from project CSPO2/02 for which a final report was completed in Sept. 2005. This earlier project identified pre-dawn leaf water potential and stomatal conductance as two measures worthy of development.

Summary

Field experiments and testing of tools coincided with a visit from Professor Hamlyn Jones from the University of Dundee, a world leader in the development of methods to assess stomatal opening from measurements of canopy temperature. Work was undertaken at Yalumba’s Oxford Landing vineyard at Waikerie, where five levels of irrigation were applied to Cabernet Sauvignon vines on Ramsey rootstock. Stomatal conductance was measured with a porometer and up to 25 measurements were made on sun-exposed leaves of each treatment. Infrared measurements were made and solar radiation, ambient humidity and other factors were also logged.

Results validated methods first described in CSP02/02, this time using large scale vineyard operations in a truly commercial setting. Since the initial project resources of CSIRO and the SA Research and Development Institute have continued to develop methods to assess vine performance using infrared thermometry in collaboration with Yalumba Wines, Measurement Engineering Australia and Professor Jones. Algorithms for data manipulation have now been developed to the point where infrared thermometry data can be used (along with other environmental information) to calculate canopy conductance.

Further development will require benchmarking major wine grape varieties for seasonal and diurnal changes and rectification of minor errors in calculation through refinement of instruments. There is potential, however, for commercial development of new tools for irrigation scheduling.