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IVES 9 IVES Conference Series 9 OIV 9 OIV 2024 9 Orals - Viticulture, table grapes, dried grapes and unfermented grape products 9 Shading nets for the adaptation to climate change: effect on vine physiology and grape quality 

Shading nets for the adaptation to climate change: effect on vine physiology and grape quality 

Abstract

Viticulture is increasingly threatened by climate change since higher temperatures and heat waves negatively affect the vines’ performance and alter grape production. Shading nets represent an interesting adaption strategy to reduce abiotic stresses thanks to their protective effects on the canopy microclimate. This study investigates the impact of shading nets with two different shading capacities (18% and 40%, respectively) on the production and quality of Sangiovese grapes cultivated in Montalcino, Tuscany (Italy). The shading nets made it possible to reduce the internal temperatures of the berries in the hottest hours of the summer months. The vines covered with shading nets produced grapes with higher yields and berry weights due to lower cluster dehydration. The grapes had lower sugar concentrations while maintaining higher levels of total acidity in musts and had an improved phenolic composition. According to the results, shading nets emerged as an effective tool for modulating factors influencing grape physiology and maturity dynamics and preserving grape quality even in case of extreme weather events.

Reti ombreggianti per l’adattamento ai cambiamenti climatici: effetto sulla fisiologia delle viti e sulla qualità dell’uva

I cambiamenti climatici costituiscono una minaccia per la viticoltura, infatti temperature più elevate determinano un’accelerazione dei processi di maturazione, che possono essere dannosi per la qualità del vino. Nell’area mediterranea sono inoltre sempre più frequenti le ondate di calore, con conseguente blocco dell’attività vegetativa delle viti ed incremento della suscettibilità a danni da scottature. Sono quindi necessarie strategie di adattamento per ridurre lo stress e migliorare la qualità della produzione. Tra le varie tecniche disponibili, le reti ombreggianti rappresentano un’alternativa interessante per i loro effetti sul microclima della chioma: riduzione dell’attività fotosintetica, miglioramento dell’efficienza nell’uso dell’acqua e rallentamento del processo di maturazione. La presente ricerca indaga l’impatto di due tipi di reti ombreggianti, rispettivamente con capacità di ombreggiamento del 18% e del 40% della radiazione fotosinteticamente attiva (par), sulla produttività e sulla qualità di uve sangiovese coltivate a montalcino (toscana, italia).  La presenza delle reti ombreggianti ha ridotto la temperatura interna degli acini da 1,5 a 2,5 °c, nelle ore più calde dei mesi estivi. Le reti ombreggianti hanno consentito rese più elevate dovute all’aumento del peso degli acini. L’uva ha evidenziato concentrazioni di zuccheri più basse e concentrazioni più elevate di acido malico, che hanno influenzato positivamente l’acidità titolabile dei mosti. Nonostante l’aumento della produzione, le quantità di antociani nelle bucce sono rimaste stabili. La ridotta esposizione al sole ha, però, modificato il profilo degli antociani, favorendo percentuali più elevate di malvidina. Inoltre, le uve ombreggiate hanno mostrato una diminuzione significativa del contenuto di quercetina.  Gli effetti osservati sono risultati correlati alla capacità ombreggiante delle reti, pur consentendo la completa maturazione delle uve anche nel caso della copertura del 40% della par. Sui filari ombreggiati non è stata inoltre riscontrata una maggiore sensibilità alle patologie fungine.  In conclusione, le reti ombreggianti si sono rivelate uno strumento efficace per modulare i fattori che influenzano la dinamica della maturazione dell’uva, permettendo di preservare la produzione e la qualità delle uve anche in caso di eventi meteorici estremi.

Filets d’ombrage pour l’adaptation au changement climatique: effet sur la physiologie viticole et la qualité du raisin

Le réchauffement climatique constitue une menace sérieuse pour la viticulture. En effet, des températures plus élevées provoquent une accélération des processus de maturation des raisins qui compromettent la qualité du vin. Par ailleurs, dans les vignobles du bassin méditerranéen sont de plus en plus fréquentes des vagues de chaleur qui provoquent le blocage de l’activité végétative des vignes et augmentent la sensibilité des grappes à la brûlure solaire. Pour ces raisons, l’introduction de stratégies d’adaptation est nécessaire pour réduire le stress et améliorer la production. Parmi les techniques disponibles, les filets d’ombrage représentent une alternative intéressante en raison de leurs effets sur le microclimat de la canopée, à savoir une réduction de l’activité photosynthétique, une meilleure efficacité dans l’utilisation de l’eau disponible et un ralentissement du processus de maturation. Cette recherche vise à évaluer l’impact de deux types de filets d’ombrage, respectivement avec une capacité de filtrage de 18% et 40% du rayonnement photosynthétiquement actif (par) sur la productivité et la qualité des raisins cépage sangiovese cultivés à montalcino (toscane, italie). La présence de filets d’ombrage a diminué la température interne des baies de 1,5 à 2,5 °c pendant les heures les plus chaudes des mois d’été. Les rendements des raisins mûris sous les filets ont été plus élevés en raison de l’augmentation du poids des baies. Les raisins avaient une teneur en sucre plus faible et des concentrations plus élevées d’acide malique, maintenant ainsi une acidité optimale du moût. Malgré l’augmentation de la production, les quantités d’anthocyanes dans les peaux sont restées stables. Cependant, la moindre exposition au soleil a modifié le profil des anthocyanes, favorisant la synthèse de pourcentages plus élevés de malvidine. De plus, les raisins ombragés avaient une teneur en quercétine considérablement réduite. D’après nos résultats, les effets ont été proportionnels selon les deux types de filtrage des filets et la maturation des raisins a été complète même sous le filet avec une réduction de 40% du par. Dans les deux traitements entre les rangs ombragés, aucune augmentation de la sensibilité aux maladies cryptogamiques n’a été trouvée. En conclusion, les filets d’ombrage se révèlent être un moyen efficace pour moduler les facteurs qui influencent la dynamique de maturation de la vigne et permettent de préserver la production et la qualité en cas d’événements climatiques extremes.

DOI:

Publication date: November 18, 2024

Issue: OIV 2024

Type: Article

Authors

Paolo Storchi¹, Marco Ammoniaci¹, Sergio Puccioni¹, Alessandra Zombardo¹, Paolo Valentini¹, Rita Perria¹

¹ CREA – Research Centre for Viticulture and Enology, Viale S. Margherita, 80, Arezzo, Italy

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Full papers OIV 2024 | IVES Conference Series | OIV | OIV 2024

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