2.1. Experimental site and plant material
The study was carried out at the St. Nicholas Hill Research
Station of the Institute of Viticulture and Oenology, University of
Pécs, Hungary. We studied four grapevine (V. vinifera L.) cultivars:
‘Sauvignon Blanc’ (SB) and ‘Riesling’ (RI) (convarietas occidentalis);
‘Lemberger’ (LE) (convarietas orientalis) and ‘Kadarka’ (KA) (convari-
etas pontica),which have different origins and taxonomic positions
according to ampelographic classifications (Németh, 1967). Each
variety was grafted on a generally used rootstock (‘Teleki 5C’, Vitis
berlandieri×Vitis riparia hybrid).
Five-year-old vines were grown on south-facing slopes and
terraces of the Mecsek Hills (latitude: 46◦07
N, longitude: 18◦17
E, 200m elevation) in non-irrigated field conditions. The soil was
a Ramann-type brown forest soil mixed with clay, formed on
Pannonian red sandstone. Vines were trained to an umbrella sys-
tem with 2.0m×1.0m row by vine spacing. Row direction was
North–South on steep slopes and East–West on micro terraces.
Steep slopes are typically characterized as severely eroded sites
with shallow soil layer. Representative leaf samples for measure-
ments originated from homogeneous plantings with 100 vines
of each cultivar. The site is situated within the Praeillyricum
(plant geographical district), which on average receives 782mm
of precipitation per year, 2021 h of sunshine annually and with
an annual mean temperature of 11.6 ◦C. However, the mesoclimatic characteristics of the site show significant extremes in precipitation events (344–1140mm), in amount of sunshine hours
(1986–2548 h) and in annual mean temperature (9.3–14.0 ◦C)
according to data collected between 1950 and 2005 (IVO, 2010).