Improving water use efficiency, canopy structure and grape quality by better matching rootstock and scion physiology to irrigation practice

Abstract

Research on Partial Rootzone Drying (PRD) has highlighted the importance of root sourced chemical messages such as abscisic acid (ABA) in controlling water use in grapevine. The main objectives of CRV 99/8 were to determine whether changing root genotype by grafting to commercial rootstocks would provide a further means to manipulate these signals and thus modify water use efficiency, and to determine how grapevine varieties differ in response to atmospheric and soil moisture deficits. This work was carried out at vineyards at the University of Adelaide and the SARDI Barossa Valley Field Station. The results show that rootstocks have potential to influence vine water use and that these differences are reflected in xylem sap ABA concentration when vines are under stress. Variation was also found in the response of different commercial scion varieties to water deficits, which should be considered when deciding upon management of water resources in the vineyard.

Summary

Prior to the commencement of CRV 99/8 published information on how rootstocks could be expected to perform under water limiting conditions was based largely on survey data and anecdotal information. The aims of this project were to provide scientific evidence for the potential of rootstocks to alter vine water use and to establish a better understanding of the physiological mechanisms driving this potential. Research on partial rootzone drying (PRD) had previously demonstrated the importance of root derived chemical signals, in controlling water use efficiency (WUE).