The Suitability of Indigenous Cypriot Grape Varieties to Viticulture and Oenology in Australia

Abstract

The threat of climate change to the global wine industry is well documented. As such, many wine regions of the world are expected to face significant impacts in the next 50 years encompassing increasing temperatures, reduced rainfall, earlier harvests and heat induced berry composition changes. The majority of vineyards and wineries base their businesses on European grape varieties that traditionally do not have problems with water resources. This has led countries to investigate options to adapt to these challenges, with a particular focus on the drought and heat tolerant indigenous grape varieties of hot Mediterranean climates. Recently in Australia, producers have been seeking potential drought tolerant varieties from Greece, Portugal, Spain and Georgia. However, very little research has assessed these varieties under Australian conditions and there is a lack of knowledge on how they perform. The island of Cyprus is another hot wine growing region with a recent upsurge in interest and research into heat and drought tolerance and a return to cultivation of their indigenous varieties. To date there are at least 12 indigenous varieties that have been identified in Cyprus, but recent research indicates there could be more varieties and numerous clones in their germplasm. The aims of this project were to investigate the potential of two indigenous grape varieties from Cyprus for use in Australian viticulture and oenology. They objectives to meet these aims included: (1) generate sensory and chemical profiles of commercial Cypriot wines made from the white grape Xynisteri and the red grapes Maratheftiko and Giannoudhi compared to Australian Shiraz, Pinot Gris and Chardonnay wines, (2) assess the Australian consumers’ response to these wines, (3) investigate five potent thiols in Xynisteri, Maratheftiko, Giannoudhi, Pinot Gris, Chardonnay and Shiraz wines, (4) formulate a baseline understanding of the performance of the indigenous Cypriot white grape Xynisteri and the red grape Maratheftiko (Vitis vinifera L.), (5) compare these varieties to Shiraz and Sauvignon Blanc grown in a Cypriot vineyard, (6) assess the response of Xynisteri to different irrigation regimes and (7) compare the performance of Xynisteri, Maratheftiko, Shiraz and Sauvignon Blanc grown in pots with different irrigation regimes in Australia and Cyprus. This research has addressed the seven aims by providing new knowledge on several aspects of Xynisteri and Maratheftiko grapevines and their wines. They include, the chemical composition and sensory attributes of wines made from these varieties. Consumers have demonstrated a liking for the wines and in some cases preferred these wines to wine made from more common varieties. Xynisteri was described sensorially as citrus, herbaceous, dried fruit, savoury, apple, pear, grass, herbaceous with a full length of fruit and non-fruit flavours in the after taste. Maratheftiko was described sensorially as dried fruit, strawberry, cherry, jammy, confectionery, bitter, sweet, chocolate, herbaceous and with full length of fruit flavours in the after taste. For the first time, chemical analysis supported this sensory analysis with aroma compounds correlating to chemical compounds responsible for these aromas and tastes. Varietal thiols are important compounds in certain varieties when fruity, tropical and citrus aromas are desired. This study measured the concentration of varietal thiols in these Cypriot wines and the concentration determined in these wines was comparable to those found in popular Australian wines such as Chardonnay and Sauvignon Blanc. Xynisteri and Maratheftiko growing in non-irrigated vineyards in Cyprus were bench marked against more commonly grown varieties for the first time. Along with this, irrigation trials in Australia and Cyprus compared the vine growth response to different irrigation regimes and highlighted that the Cypriot varieties were better suited to heat and drought stress than more commonly grown varieties due to their stomatal density and stomatal conductance assisting in managing midday stem water potential under heat and drought stress. Xynisteri in particular, was able to produce large above and below ground biomass under all irrigation conditions. Maratheftiko achieved large above ground biomass also but less below ground biomass than Xynisteri. However, both Xynisteri and Maratheftiko had total biomass greater than Shiraz and Sauvignon Blanc. This research has identified several aspects of the Cypriot varieties Xynisteri and Maratheftiko that may make them suitable for cultivation in Australia. Consumer trials indicated acceptance of wines made from these varieties, highlighting potential marketing opportunities to target markets. It has also provided information that will guide future research in terms of how these varieties perform in Australian commercial vineyards and the mechanisms by which they achieve their drought resilience.