K.J. Sommer, F. Hancock, M. Downey, I. Goodwin
Vineyards situated along the lower Murray River in south eastern Australia during the 2007-2008 and the 2008-2009 growing seasons suffered from severe water restrictions due to drought. In response, producers adopted a strategy of deficit irrigation by temporarily cutting off or reducing irrigation to their vineyards. To investigate the impact of deficit irrigation on dried vine fruit production, a field experiment using the variety ‘Sunmuscat’ grafted to 1103 Paulsen was established. Four deficit irrigation treatments were applied and were compared with vines that had received their full irrigation requirement (100% ETc). Three of the four deficit treatments were applied as sustained deficit irrigation (SDI) where the applied water was respectively 75, 50 and 25% of fully irrigated vines. The fourth, a regulated deficit or strategic irrigation (RDI), was mostly applied in the period between flowering and fruit set and received the equivalent of ~75% of the volume of fully watered vines. Half of the vines were also de-fruited. The experiment was conducted over 2 seasons. Imposing the deficit irrigation treatments had a marked effect on vine physiology in the first season of the experiment and reduced the production of ‘Sunmuscat’ commensurate with the severity of the imposed deficits. Fewer canes matured on vines irrigated with 25% SDI relative to the other treatments. Removing the fruit at the beginning of the season did alleviate the effect of the deficits regardless of severity. Repeated and heavy rainfall and high humidity in the second season largely negated the effect of the deficit treatments resulting in only minor physiological and production differences. Results indicate that in seasons with average weather plant water deficits lower than 75% are unlikely to sustain ‘Sunmuscat’ productivity in the short term but deficits of up to 75% appear to maintain optimal productivity.
Sommer, K.J., Hancock, F., Downey, M. and Goodwin, I. (2014). IMPACT OF DEFICIT IRRIGATION ON 'SUNMUSCAT' PRODUCTION IN AUSTRALIA . Acta Hortic. 1038, 579-586
DOI: 10.17660/ActaHortic.2014.1038.73
dried grape, water stress, stem water potential, sustained deficit irrigation, regulated deficit irrigation

Acta Horticulturae