Survey of phenological stages of disease-resistant varieties in Friuli Venezia Giulia region

Abstract

Context and purpose of the study. The primary fungal diseases affecting grapevines in Europe are downy mildew and powdery mildew. European viticulture accounts for approximately 3% of the agricultural surface, although it accounts for 65% of all fungicides used in agriculture. Since the adoption of varieties produced with cis-genesis or genome editing is currently not allowed in Europe, disease resistance genes have been introduced into grapevine genotypes with controlled interspecific crosses. In recent decades, breeding programs have been established across Europe and overseas, leading to the investigation of different hybrids, many of which also adopted for cultivation.

Material and methods. Starting from 2021, a four years project was funded with the aim of understanding the suitability of different grapevine hybrids for cultivation in Friuli Venezia Giulia region (Northern Italy). During each season, grapevine phenology was monitored weekly in 38 resistant cultivars to assess the phenological progression of vegetative and reproductive stages. Budburst (BBCH 08), full flowering (BBCH 65), veraison (BBCH 81) and maturation (BBCH 89) dates were precisely determined. Weather data were used to calculate GDDs relative to each phenological stage and variety.

Results. Phenology data explored using PCA revealed distinct budbreak, flowering and veraison timings among different grapevine hybrids. Cultivars Fleurtai, Civit 2 and Prior appeared the most representative early budbreak varieties. On the other hand, Aromera and Sauvignon Rytos were clearly distinguishable as the latest varieties. Several early-flowering varieties were detected, with Solaris and Prior as models. The least precocious cultivars included Sauvignon Rytos and Cabernet Eidos. Interestingly, Civit 2 was detected among the most delayed varieties in terms of veraison despite being early for both budbreak and flowering. Helios and Cabernet Volos resulted instead as quickest in reaching the same phenological phase. The multivariate analysis adopted also made it possible to categorize the varieties according to their stability throughout the seasons.

These data, together with the grape maturity parameters (soluble solids, titratable acidity, etc.), will be of importance to understand the most promising varieties to be cultivated in the Friuli Venezia Giulia region in the frame of climate change.