Touriga Naçional x environment interaction in the Little Karoo region of South Africa
Date
2009-12
Authors
Nel, Margaux
Journal Title
Journal ISSN
Volume Title
Publisher
Stellenbosch : University of Stellenbosch
Abstract
ENGLISH ABSTRACT: The Little Karoo region of South Africa stretches from Montagu in the west, through Barrydale
on the Langeberg Mountain, towards Ladismith, Calitzdorp, Oudtshoorn and De Rust in the
east, with the Swartberg mountain range in the north.
The Wine of Origin district of Calitzdorp is a small, demarcated area around Calitzdorp in
the Little Karoo, surrounded by the Rooiberg, Swartberg and Kleinberg mountains.
With a mean February temperature (MFT) of 23.7ºC and a low annual rainfall of 233 mm,
the district of Calitzdorp has a similar climate to that of the Douro Demarcated Region (DDR).
The MFT is comparable to the DDR mean July temperature, and it seems that the Douro
Superior sub-region to the east of the DDR has a mean July temperature of higher than 25°C. In
the Cima Corgo sub-region (in the centre of the DDR), and the Baixo Cargo sub-region, the
mean July temperatures are ±25°C and ±22°C respectively. Annual rainfall in the DDR is much
higher, with Baixo Cargo recording 1 018 mm, Cima Corgo recording 658 mm and Douro
Superior in the east recording only 437 mm.
Touriga Naçional is one of the highest quality Portuguese red grape varieties. It produces
high-quality port-style wine as well as table wines. Excellent quality Touriga Naçional wines
have a dark black/purple colour, good extract, high, elegant tannin content and intense aromas,
with typical plum, raisin, wild fruit, mulberry, “fynbos” and cherry aromas.
The most suitable terroir for Touriga Naçional in the DDR has been found to be on sites that
restrain the natural vigour of the grapevine. Soils with moderate to low water-holding capacity, in
association with low rainfall, result in water deficits during the growing season and are
considered optimal to restrict growth vigour.
A steep, northern middle slope is ideal in the southern hemisphere for high temperatures
and sunlight interception. Warm temperatures (25 to 30 °C) during the day and cooler
temperatures during the night are optimal for photosynthesis and colour development.
In order to study factors affecting the quality of Touriga Naçional in Calitzdorp, two Vitis
vinifera L. cv. Touriga Naçional commercial vineyards in the Calitzdorp district were selected.
Each vineyard was divided into two separate management blocks based on their empirically
determined quality of production. Two crop-reduction treatments, the standard 50% crop
reduction (which was considered to be the control) and a further less drastic treatment of 25%
crop reduction, were applied.
Significant differences were found in viticultural performance between the two adjacent
Touriga Naçional management blocks in each vineyard, especially with respect to vigour. The
upper management blocks, which provided grapes for reserve-quality port-style wines,
experienced a higher water deficit due to the moderate soil water-holding capacity and higher
temperatures in comparison to the lower sites. The higher water deficits had a restraining effect
on the Touriga Naçional vines, and therefore the upper sites had lower vigour, which
contributed to better quality of both the wine and port-style wine, and this could be recognised
sensorially. However, it was not reflected in the chemical analytical results.
Crop load also appeared to have an effect on the Touriga Naçional grapevines, but this
appeared to be dependent on the management block. The 50% crop reduction had a significant
positive effect on the sensory analyses, but did not significantly affect the chemical analyses.
Calitzdorp terroir has a similar effect on Touriga Naçional compared to the DDR terroir, and
that is why Calitzdorp can produce good table and port-style wines from Touriga Naçional.
AFRIKAANSE OPSOMMING: Die Klein Karoo-streek in Suid Afrika strek vanaf Montagu in die weste, deur Barrydale teen die Langeberg, na Ladismith, Calitzdorp, Oudtshoorn en De Rust in die ooste, met die Swartberg in die noorde. Die distrik van Calitzdorp is ‘n klein area rondom Calitzdorp, in die Klein Karoo, wat deur die Rooiberg, Swartberg en Kleinberg omring is. Calitzdorp het ‘n gemiddelde Februarie-temperatuur (GFT) van 23.7°C en ‘n lae jaarlikse reënval van 223 mm, wat soortgelyk is aan die klimaat van die Douro Vallei in Portugal. Die Douro Vallei se gemiddelde Julie-temperatuur (GJT) in vergelyking met die GFT van Calitzdorp is hoër, met temperature van meer as 25°C in die substreek Douro Superior. Vir die substreke Cima Cargo en Baixo Cargo is die GJT ±25°C en ±22°C onderskeidelik. Die jaarlikse reënval is ook hoër by Baixo Cargo, met 1 018 mm, Cima Cargo met 658 mm en Douro Superior met slegs 437 mm. Touriga Naçional is een van die beste Portugese rooi kultivars wat hoëkwaliteit tafel- en portwyne produseer. ‘n Tipiese hoëkwaliteit Touriga Naçional-wyn het ‘n swartpers kleur, hoë ekstrak, hoë elegante tanniene en intense aromatiese geure wat tipiese pruim, rosyne, wilde vrugte, moerbei, fynbos en kersie aromas insluit. Die geskikste terroir vir Touriga Naçional is op swak gronde wat die natuurlike groeikrag van die wingerdstok strem. Gronde met matige tot lae grondwaterhouvermoë tesame met lae reënval veroorsaak ‘n waterstremming in die wingerdstok gedurende die groeiseisoen en word as optimaal beskou omdat dit beheersde groei veroorsaak. In die suidelike halfrond word relatief steil, noordelike middelhange as ideaal beskou vir hoë temperature en maksimale sonligonderskepping. Gepaardgaande hiermee is die interne dreinasie verantwoordelik vir vinniger uitdroging van die grond. Hoë temperature (25 tot 30°C) gedurende die dag en koue nagte is optimaal vir fotosintese en kleurontwikkeling. Twee Vitis vinifera L. cv. Touriga Naçional kommersiële wingerde in die Calitzdorp-distrik is geselekteer en in twee afsonderlike bewerkingsblokke verdeel, gebaseer op kwaliteitsverskille. In elke blok was die verdeling van so ‘n aard dat daar ‘n hoërliggende helfte en ‘n laerliggende helfte was. Twee trosverminderingsbehandelings, nl. 50% (kontrole) en 25%, gebaseer op trosgetalle, is toegepas. By elkeen van die wingerde was daar betekenisvolle groeiverskille tussen die twee aangrensende helftes. Die boonste helftes (of gedeeltes) het minder gegroei a.g.v. ‘n hoër waterstremming sowel as hoër temperatuur as die laer helftes. Dit het geblyk om ‘n positiewe invloed op die kwaliteit van beide die tafel- en portwyne uit te oefen. Troslading het ook ‘n effek op die Touriga Naçional-wingerde gehad, maar dit blyk of dit blok-afhanklik is. Die 50% trosverminderingsbehandeling het ‘n beduidende positiewe verskil in die sensoriese analises gemaak, maar nie ‘n beduidende verskil in die chemiese analises van die wyne nie. Calitzdorp se terroir het ‘n soortgelyke effek op Touriga Naçional as dié van die DDR terroir en daarom kan Calitzdorp soortgelyke goeie tafel- en portwyne van Touriga Naçional produseer.
AFRIKAANSE OPSOMMING: Die Klein Karoo-streek in Suid Afrika strek vanaf Montagu in die weste, deur Barrydale teen die Langeberg, na Ladismith, Calitzdorp, Oudtshoorn en De Rust in die ooste, met die Swartberg in die noorde. Die distrik van Calitzdorp is ‘n klein area rondom Calitzdorp, in die Klein Karoo, wat deur die Rooiberg, Swartberg en Kleinberg omring is. Calitzdorp het ‘n gemiddelde Februarie-temperatuur (GFT) van 23.7°C en ‘n lae jaarlikse reënval van 223 mm, wat soortgelyk is aan die klimaat van die Douro Vallei in Portugal. Die Douro Vallei se gemiddelde Julie-temperatuur (GJT) in vergelyking met die GFT van Calitzdorp is hoër, met temperature van meer as 25°C in die substreek Douro Superior. Vir die substreke Cima Cargo en Baixo Cargo is die GJT ±25°C en ±22°C onderskeidelik. Die jaarlikse reënval is ook hoër by Baixo Cargo, met 1 018 mm, Cima Cargo met 658 mm en Douro Superior met slegs 437 mm. Touriga Naçional is een van die beste Portugese rooi kultivars wat hoëkwaliteit tafel- en portwyne produseer. ‘n Tipiese hoëkwaliteit Touriga Naçional-wyn het ‘n swartpers kleur, hoë ekstrak, hoë elegante tanniene en intense aromatiese geure wat tipiese pruim, rosyne, wilde vrugte, moerbei, fynbos en kersie aromas insluit. Die geskikste terroir vir Touriga Naçional is op swak gronde wat die natuurlike groeikrag van die wingerdstok strem. Gronde met matige tot lae grondwaterhouvermoë tesame met lae reënval veroorsaak ‘n waterstremming in die wingerdstok gedurende die groeiseisoen en word as optimaal beskou omdat dit beheersde groei veroorsaak. In die suidelike halfrond word relatief steil, noordelike middelhange as ideaal beskou vir hoë temperature en maksimale sonligonderskepping. Gepaardgaande hiermee is die interne dreinasie verantwoordelik vir vinniger uitdroging van die grond. Hoë temperature (25 tot 30°C) gedurende die dag en koue nagte is optimaal vir fotosintese en kleurontwikkeling. Twee Vitis vinifera L. cv. Touriga Naçional kommersiële wingerde in die Calitzdorp-distrik is geselekteer en in twee afsonderlike bewerkingsblokke verdeel, gebaseer op kwaliteitsverskille. In elke blok was die verdeling van so ‘n aard dat daar ‘n hoërliggende helfte en ‘n laerliggende helfte was. Twee trosverminderingsbehandelings, nl. 50% (kontrole) en 25%, gebaseer op trosgetalle, is toegepas. By elkeen van die wingerde was daar betekenisvolle groeiverskille tussen die twee aangrensende helftes. Die boonste helftes (of gedeeltes) het minder gegroei a.g.v. ‘n hoër waterstremming sowel as hoër temperatuur as die laer helftes. Dit het geblyk om ‘n positiewe invloed op die kwaliteit van beide die tafel- en portwyne uit te oefen. Troslading het ook ‘n effek op die Touriga Naçional-wingerde gehad, maar dit blyk of dit blok-afhanklik is. Die 50% trosverminderingsbehandeling het ‘n beduidende positiewe verskil in die sensoriese analises gemaak, maar nie ‘n beduidende verskil in die chemiese analises van die wyne nie. Calitzdorp se terroir het ‘n soortgelyke effek op Touriga Naçional as dié van die DDR terroir en daarom kan Calitzdorp soortgelyke goeie tafel- en portwyne van Touriga Naçional produseer.
Description
MScAgric
Keywords
Touriga Naçional, Dissertations -- Viticulture and oenology, Theses -- Viticulture and oenology