Seasonal growth and gas exchange of conventionally and minimally pruned Chardonnay canopies

The net CO2 gas exchange rate (NCER) of hand(HP) and minimally pruned (MP) potted Chardonnay canopies was continuously monitored from about 20 d after budburst until post-harvest. Single-leaf gas exchange readings were taken 4 times throughout the season and non-destructive estimates of leaf chlorop hyll at veraison, Canopy leaf area development was registered, yield compon ents and grape soluble solids were recorded at harvest; samples were taken to determine dry matter partitioning into clusters, leaves and canes. The MP vines showed higher shoot number, distinctly reduced leaf and shoot size, and a higher cluster number with smaller berries and less berries per cluster compared to HP vines, The MP vines exhibited a 4-6-fold higher CO2 fixation than HP vines from about three weeks after budbreak till bloom. C anopy NCER started to recover in RP vines concurrently with the transition to a faster shoot growth phase, although by canopy completion NCER was stil l 13 % higher in MP. Sugar concentration of berries was not significantly l ower in MP compared to up despite a yield increase of about 70 %, The overa ll results indicate minimal pruning as a valuable tool to improve the perfo rmance of Chardonnay vines under our experimental conditions.