Variability in flowering, fruit set and yield in response to vineyard topography and pruning type in Pinot noir

Abstract

Aim: This study investigates the effects of site aspect and pruning management on flowering, fruit set and yield in Pinot noir vines. Methods: Two rows of 19-year-old Pinot noir vines were selected within a commercial vineyard with south, hilltop, and north-facing aspects. Vines were either cane- or spur-pruned, retaining 20 nodes per vine. One monitoring vine was selected at each sub-plot (consisting of four vines) and used to assess days to 50% flowering, fruit set (%) and days to 50% veraison. Total soluble solids samples were taken from each sub-plot and vines were harvested separately for yield. Results/Findings: Days to 50% flowering was affected by the topographical position. Vines from south-facing plots reached 50% flowering three days earlier during 2018-19 and eight days earlier 2020-21 compared to other plots. Cane pruning advanced the flowering date by one day compared with spur pruned vines (2019-20). Fruit set (%) was affected by topography. Vines from the hilltop plots had less than 50% fruit set during 2018-19 and 2020-21 compared to south and north plots (>70% fruit set). The lower fruit set was reflected in reduced yields. Despite the delayed flowering, vines from the hilltop position reached 50% veraison four days earlier than vines from the south and north plots during 2020–21. While there were initial differences in total soluble solids (at 7 to 8 oBrix) at six topographical positions, these variations disappeared by the time the vines were ready for a commercial harvest (>20 oBrix). The type of pruning generally had little effect on fruit set, the date of véraison or soluble solids at harvest, although cane pruning resulted in a 40% increase in yield in 2019–20 when compared to spur pruning. Conclusions: Flowering, fruit set, veraison, and vine yield were affected by topography (site aspect) and pruning type had little to no effect. Vine yield was a reflection of the fruit set (%) with differences between topographical positions. Positions with delayed veraison showed delayed soluble solids accumulation but reached a similar harvest soluble solids and yield.