2014 ASHS Annual Conference
18478:
cv. Syrah) Cultivar Under Mechanical Canopy Management
18478:
cv. Syrah) Cultivar Under Mechanical Canopy Management
Thursday, July 31, 2014: 2:30 PM
Salon 9/10 (Rosen Plaza Hotel)
A trial in the San Joaquin Valley of California investigated how the interaction
of pruning systems and mechanical shoot thinning affected canopy performance, yield
components, fruit phenolic composition at harvest, and production efficiency of a procumbent
cultivar in a warm climate grape-growing region. Two pruning systems and
three shoot thinning treatments were arranged factorially in a randomized complete
block design with four replications. The pruning methods were applied by either handpruning
to a target of 25 nodes/m or mechanically hedging and retaining a 100-mm spur
height. The shoot density treatments were applied mechanically at a modified Eichhorn-
Lorenz scale, stage 17 to retain 40 or 45 shoots/m of a row, or left unthinned. The
contribution of count shoots to total shoots increased when mechanical box pruning
replaced spur pruning. The contribution of percent count shoots to total shoots was
greatest with 40 shoots/m and unthinned treatments. The percent photosynthetically
active radiation (PAR) transmission and percent canopy gaps increased with mechanical
box pruning and also with the decrease in shoot density per meter of row. Berry and
cluster size decreased with mechanical box pruning application. However, because
mechanically box-pruned vines carried more clusters, yield per meter of row increased.
There was a quadratic response to shoot thinning where berry skin phenolics, anthocyanins,
and tannins decreased with the 45 shoots/m treatment when compared with
40 shoots/m and unthinned treatments. Pruning weight per meter of row and leaf area-to fruit
ratio decreased, whereas Ravaz Index (kg yield/kg pruning weight) increased with
mechanical box pruning. Shoot thinning treatments did not affect pruning weight per
meter of row or leaf area-to-fruit ratio. Increasing amount of PAR and percent canopy
gaps by shoot thinning resulted in vegetative compensation from a sparsely populated
grapevine canopy, thereby negating its purported effects. The 40 and 45 shoots/m
treatments repopulated the canopy rapidly with non-count shoots thereby increasing the
pruning weight per meter of row at the end of the season. In the absence of a physiological
response, shoot thinning in a procumbent cultivar is not recommended. Mechanically
box pruning to a 100-mm spur height and slowing down vegetative growth by irrigating
to 50% of daily evapotranspiration (ETo) variance between fruit set and veraison have
resulted in a Ravaz Index window (5 to 10 kg·kg-1) and is recommended for procumbent
red wine grape cultivars for the region with similar or better berry skin phenolic
accumulation than spur-pruned vines.
of pruning systems and mechanical shoot thinning affected canopy performance, yield
components, fruit phenolic composition at harvest, and production efficiency of a procumbent
cultivar in a warm climate grape-growing region. Two pruning systems and
three shoot thinning treatments were arranged factorially in a randomized complete
block design with four replications. The pruning methods were applied by either handpruning
to a target of 25 nodes/m or mechanically hedging and retaining a 100-mm spur
height. The shoot density treatments were applied mechanically at a modified Eichhorn-
Lorenz scale, stage 17 to retain 40 or 45 shoots/m of a row, or left unthinned. The
contribution of count shoots to total shoots increased when mechanical box pruning
replaced spur pruning. The contribution of percent count shoots to total shoots was
greatest with 40 shoots/m and unthinned treatments. The percent photosynthetically
active radiation (PAR) transmission and percent canopy gaps increased with mechanical
box pruning and also with the decrease in shoot density per meter of row. Berry and
cluster size decreased with mechanical box pruning application. However, because
mechanically box-pruned vines carried more clusters, yield per meter of row increased.
There was a quadratic response to shoot thinning where berry skin phenolics, anthocyanins,
and tannins decreased with the 45 shoots/m treatment when compared with
40 shoots/m and unthinned treatments. Pruning weight per meter of row and leaf area-to fruit
ratio decreased, whereas Ravaz Index (kg yield/kg pruning weight) increased with
mechanical box pruning. Shoot thinning treatments did not affect pruning weight per
meter of row or leaf area-to-fruit ratio. Increasing amount of PAR and percent canopy
gaps by shoot thinning resulted in vegetative compensation from a sparsely populated
grapevine canopy, thereby negating its purported effects. The 40 and 45 shoots/m
treatments repopulated the canopy rapidly with non-count shoots thereby increasing the
pruning weight per meter of row at the end of the season. In the absence of a physiological
response, shoot thinning in a procumbent cultivar is not recommended. Mechanically
box pruning to a 100-mm spur height and slowing down vegetative growth by irrigating
to 50% of daily evapotranspiration (ETo) variance between fruit set and veraison have
resulted in a Ravaz Index window (5 to 10 kg·kg-1) and is recommended for procumbent
red wine grape cultivars for the region with similar or better berry skin phenolic
accumulation than spur-pruned vines.