Nebulized water cooling of the canopy affects leaf temperature, berry composition and wine quality of Sauvignon blanc.
BACKGROUND
The present paper details a new technique based on spraying nebulized water on vine canopy to counteract the negative impact of the current wave of hot summers with temperatures above 30 °C, which usually determine negative effects on vine yield, grape composition and wine quality.


RESULTS
The automatized spraying system was able to maintain air temperature at below 30 °C (the threshold temperature to start spraying) for all of August 2013, when in the canopy of uncooled vines the temperature was as high as 36 °C. The maintenance of temperature below 30 °C reduced leaf stress linked to high temperature and irradiance regimes as highlighted by the decrease of H2O2content and catalase activity in the leaves. A higher amount of total polyphenols and organic acids and lower sugars characterized the grapes of cooled vines. Wine from these grapes had a higher content of some volatile thiols like 3-sulfanylhexanol (3SH) and 3-sulfanylhexylacetate (3SHA), and lower content of 4-methyl-4-sulfanylpentan-2-one (4MSP).


CONCLUSIONS
Under conditions of high temperature and irradiance regimes, water nebulization on the vine canopy can represent a valid solution to reduce and/or avoid oxidative stress and associated effects in the leaves, ensure a regular berry ripening and maintain high wine quality. The consumption of water during nebulization was acceptable, being 180 L ha-1min-1, which lasted an average of about 1 min to reduce the temperature below the threshold value of 30 °C. A total of 85-90 hL (from 0.8 to 0.9 mm) of water per hectare per day was required. © 2016 Society of Chemical Industry.
Department for Innovation in Biological, Agro-Food and Forest systems (DIBAF), University of Tuscia, 01100 Viterbo, Italy.
Pericle
P
Paciello
Department for Innovation in Biological, Agro-Food and Forest systems (DIBAF), University of Tuscia, 01100 Viterbo, Italy.
Fabio
F
Mencarelli
Dipartimento di Scienze Agrarie, Alimentari e Ambientali, Università degli Studi di Perugia, 06121, Perugia, Italy.
Alberto
A
Palliotti
Department for Innovation in Biological, Agro-Food and Forest systems (DIBAF), University of Tuscia, 01100 Viterbo, Italy.
Brunella
B
Ceccantoni
ISVV, Unité de Recherche Œnologie, Universitè de Bordeaux, Villenave d'Ornon, France.
Cécile
C
Thibon
ISVV, Unité de Recherche Œnologie, Universitè de Bordeaux, Villenave d'Ornon, France.
Philippe
P
Darriet
Department for Innovation in Biological, Agro-Food and Forest systems (DIBAF), University of Tuscia, 01100 Viterbo, Italy.
Massimiliano
M
Pasquini
Department for Innovation in Biological, Agro-Food and Forest systems (DIBAF), University of Tuscia, 01100 Viterbo, Italy.
Andrea
A
Bellincontro
D000143:Acids / Q000378:metabolism; D000336:Aerosols; D000383:Agriculture / Q000379:methods*; D050260:Carbohydrate Metabolism; D002374:Catalase / Q000378:metabolism; D005638:Fruit / Q000378:metabolism*; D057232:Global Warming; D006801:Humans; D006861:Hydrogen Peroxide / Q000378:metabolism; D008027:Light; D018384:Oxidative Stress; D010422:Pentanones / Q000378:metabolism; D018515:Plant Leaves; D059808:Polyphenols / Q000378:metabolism; D012621:Seasons; D013438:Sulfhydryl Compounds / Q000378:metabolism; D013696:Temperature; D027843:Vitis / Q000378:metabolism*; D014867:Water; D014920:Wine / Q000032:analysis* / Q000592:standards
D000143:Acids; D000336:Aerosols; D010422:Pentanones; D059808:Polyphenols; D013438:Sulfhydryl Compounds; D014867:Water; C530764:4-methyl-4-sulfanylpentan-2-one; D006861:Hydrogen Peroxide; D002374:Catalase
Sauvignon blanc; grape composition; nebulized water cooling; warm-climate viticulture; wine thiols