Corvina berry morphology and grape composition as affected by two training system (Pergola and Guyot) in a context of climate change scenario

The Valpolicella area (Veneto Region, Italy) is famous for its high quality wines: Amarone and Recioto, both obtained from partial post-harvest dehydrated red grapes. The main cultivars used for these wines are Corvina and Corvinone. In this Region hundreds of years ago a particular training system (Pergola, cordon/cane with horizontal shoot-positioning) was developed. In the last 20 years the Guyot have been introduced in the area; now Pergola and Guyot are equally widespread in the Valpolicella area. In two different environmental conditions (hill and floodplain) two vineyards, one for each type of training system, were studied along two years (2011-2012). 

Different canopy architectures determined differences in canopy density and bunch microclimate. Point quadrat analysis (PQA), photosynthetically active radiation (PAR) in the fruiting zone and berry temperature measurements were performed to evaluate the differences between the two training systems. The different leaf layer number (LLN) between the two trellis determined a different PAR reaching the bunch that resulted in a different berry temperature. Pergola showed a higher LLN and a consequent lower berry temperature compared with Guyot trellis. 

The ThS of Pergola always showed a thinner skin compared with the Guyot. Tartaric acid content was significantly affected by the training system and resulted higher in the Pergola trellis. The ANT was higher where maximum berry temperature was lower, i. e. in intracanopy bunch of Pergola. Ew and TSS content were not affected by both the position in the canopy and the training system; just a year effect was founded. This study highlight the effect of the training system on some important grape parameters in a context of climate change, also for the post-harvest dehydration process of Corvina.