Production and quality at different canopy positions of box pruning grapevines (cv. Syrah)

Abstract

Radiation plays a key role on yield and quality. A high variability in incident radiation is observed within the leaves and grapes of a single canopy. Free-canopy training systems are being increasingly used to mechanize different operations. In these training systems, radiation is highly modified by position within the canopy. Understanding this intra-canopy variability is essential for vineyard design and management. In this study we aimed to characterize the spatial variability in yield, sugar accumulation and stomatal conductance in a box pruning training system. The experiment was carried out at the EEA INTA Junín (Mendoza, Argentina) in a vineyard trained in a box pruning system (cv. Syrah). Rows were NE-SW oriented, with 2.3m x 1.5m spacing. The canopy was divided into one position above the cordon (top), and three positions below the cordon: inner and both external sides (NW and SE). The results showed that yield (18.9 kg plant^-1) was concentrated in top (42%) and the inner (34%) positions, while 13% and 11% was distributed in SE and NW positions, respectively. Solid soluble showed scarce differences among canopy positions, being the highest in the inner grapes (22 ºBrix) and the lowest in NW position (21ºBrix). Stomatal conductance was higher at NW and SE (579 and 646 mmol m^-2 s^-1 respectively) than inner and top (308 and 427 mmol m^-2s^-1, respectively). The results highlight the existing spatial variability within the canopy on source activity and grape quality.