Vine balance metrics for cane-pruned NZ Sauvignon blanc and possible management implication

Abstract

This research characterised retained dormant shoot a ributes, described how grapevines responded to cane pruning and quan fied how that response was influenced by pruning decisions. It also supplied data and knowledge to train novice human pruners and ar ficial intelligence (AI) systems that support automated cane pruning. To characterise retained dormant shoots and grapevine response to cane pruning, eight dormant shoot a ributes – diameter, length, ver cal distance from the soil surface (VD) and horizontal distance from the vine trunk (HD), node count, internode length, origin, and posi on rela ve to bo om frui ng wire (PFW) – were measured before and a er pruning in two vineyard blocks located in the Awatere Valley, Marlborough (New Zealand) over two growing seasons. An expert human pruner with several years of experience in pruning grapevines in commercial vineyards in Marlborough was instructed to prune each vine according to the industry standard; retain six dormant shoots, mark four that will form frui ng canes and two that will form spurs. Cane pruning stripped the vine of 82% dormant shoots, the remaining 18% formed the next season’s canes and spurs. Retained and non-retained dormant shoots significantly differed in all their a ributes except for node count. On average, retained dormant shoots were 9.2±0.07 mm diameter, 104.7±0.93 cm long, 11.4±0.65 cm HD and 83.2±0.54 cm VD. Compared with non-retained, retained dormant shoots had the shortest HD (9.8±0.93 cm) and VD (77.8±0.7 cm), and originated from basal node or f irst nodes on old canes and old spurs and from the vine head. When the vine canopy was modified by changing the node numbers (from 10 to 50 nodes) retained dormant shoots on 50-node vines increased in VD (from 81.6 to 87.8 cm; p<0.05), on 10-node vines diameter increased (from 8.6 to 9.6 mm, p<0.05). PFW was the only a ribute that remained unchanged despite canopy modifica on. This research revealed that: (1) retained, non-retained dormant shoots, canes and spurs exhibited dis nct a ributes, and that (2) dormant shoot selec on in commercial vineyards was a consistent knowledge-based process that follows strict rules which could be used to train inexperienced human pruners, AI pruning systems and fully autonomous pruning robots.