Seasonal evolution impact on Montepulciano grape ripening

¹ Dipartimento di Scienze Agrarie, Ambientali ed Alimentari, D3A, Via Brecce Bianche 10, 60131 Ancona, Italy
² Azienda vitivinicola Conti degli Azzoni, Via Don Minzoni 26, 62010 Montefano (MC), Italy

^* Corresponding author: v.lanari@staff.univpm.it

Abstract

In an environmental background characterized by climate change, the seasonal trend increasingly affects the qualitative and quantitative expression of the vineyards. The sugar concentration, titratable acidity, the ratio sugar/acids and yield were related with heat accumulation (growing degree days accumulation), calculated in different period of grapevine cycle. The 21.5 °Babo threshold has been reached by Montepulciano grapes in the various years (2007-2019) even with 40 days difference. Over a period of 13 years, the sugar of Montepulciano grapes was influenced by thermal evolution between March to July. The relationship with high coefficient determination (R² 0.74) was obtained between heat accumulation and titratable acidity. According to this forecasting model, increases in heat accumulation of 100 degree-days in the period from March to June correspond to a reduction of about 0.85 g/l of acidity of the must at the harvest associated with an increase of 0.75 degree-days in the ratio between sugars and acids. The thermal evolution between June and July was correlated with yield of Montepulciano, an increase of 100 degree-days is associated with a decrease of about 1.86 t/ha. The thermal evolution between March and July is crucial for yield and grape quality of Montepulciano.