Articles
VINEYARD NITROGEN SUPPLY AND SHIRAZ GRAPE AND WINE QUALITY
Consequently, must N levels are often insufficient to sustain a fermentation through to dryness without supplementation with exogenous N. A novel N supply strategy was trialled on drip-irrigated Shiraz vines growing on three different rootstocks to improve grapejuice N levels and supply vine N needs, aiming to satisfy winemakers’ requirements for grapes that can ferment to dryness, and grape producers’ need for profitable productivity.
Targeting the Summer N uptake period resulted in significant improvements in grape juice assimilable amino N levels.
Grapes from vines receiving N during Summer had more colour than grapes from vines that received N during Autumn or unfertilised control vines.
However, potentially higher final wine colour was not realised.
Organoleptic assessment of the wines indicated that both N supply and rootstock affected final wine quality.
Vineyard N supply affected aroma as well as colour, overall impression of the wine and total score.
Wines made from grapes from vines receiving heavy applications of N were perceived to be of lower quality than wines made from grapes from vines that received no N or moderate amounts of N, irrespective of application time.
Rootstock also significantly affected wine colour and aroma.
Highly significant rootstock and N supply interactions were apparent for colour intensity,