Articles
EFFECTS OF EARLY LEAF REMOVAL ON CLUSTER MORPHOLOGY, SHOOT EFFICIENCY AND GRAPE QUALITY IN TWO VITIS VINIFERA CULTIVARS
Article number
689_24
Pages
217 – 226
Language
English
Abstract
The effects of early season leaf removal on Barbera and Trebbiano cluster morphology and grape quality were examined under potted and field conditions.
Potted, non-defoliated Barbera vines (A) were compared to treatments in which the basal portion of the shoot (nodes 1 to 8) was defoliated at a 50 or 100% level pre-anthesis (B, C), post-anthesis (D, E) or 50% both times (F). Treatments A, C, E and F were also replicated in the field using Barbera and Trebbiano grapevines.
Fruit-set was reduced by all treatments resulting in looser clusters than the control.
The minimum and maximum reduction in cluster weight was 29 and 48% for treatments B and F, respectively, in the pot study.
It was 47 and 69% for treatments F and C, respectively, in the field for Barbera and 44 and 56% for treatments F and C, respectively, for Trebbiano. In all cases cluster size reduction was due to reduced berry number rather than smaller berry size.
Sugar concentration increased for all defoliation treatments as a result of lower yield per shoot and leaf area to fruit weight ratios (shoot basis) either similar or higher than those of controls.
The amount of sugar produced per unit leaf area (shoot efficiency) did not differ significantly among treatments in the potted study or for Trebbiano in the field.
Shoot efficiency was reduced in the C treatment for Barbera in the field.
These data demonstrate the potential of early season leaf removal for crop control and improvement of fruit characteristics at medium-to-high vigor sites.
Work in progress will evaluate carry-over effects and feasibility of mechanical leaf removal in the vineyard.
Potted, non-defoliated Barbera vines (A) were compared to treatments in which the basal portion of the shoot (nodes 1 to 8) was defoliated at a 50 or 100% level pre-anthesis (B, C), post-anthesis (D, E) or 50% both times (F). Treatments A, C, E and F were also replicated in the field using Barbera and Trebbiano grapevines.
Fruit-set was reduced by all treatments resulting in looser clusters than the control.
The minimum and maximum reduction in cluster weight was 29 and 48% for treatments B and F, respectively, in the pot study.
It was 47 and 69% for treatments F and C, respectively, in the field for Barbera and 44 and 56% for treatments F and C, respectively, for Trebbiano. In all cases cluster size reduction was due to reduced berry number rather than smaller berry size.
Sugar concentration increased for all defoliation treatments as a result of lower yield per shoot and leaf area to fruit weight ratios (shoot basis) either similar or higher than those of controls.
The amount of sugar produced per unit leaf area (shoot efficiency) did not differ significantly among treatments in the potted study or for Trebbiano in the field.
Shoot efficiency was reduced in the C treatment for Barbera in the field.
These data demonstrate the potential of early season leaf removal for crop control and improvement of fruit characteristics at medium-to-high vigor sites.
Work in progress will evaluate carry-over effects and feasibility of mechanical leaf removal in the vineyard.
Authors
S. Poni, F. Bernizzoni, G. Briola, A. Cenni
Keywords
Vitis vinifera, summer pruning, cluster size, grape quality, source-sink balance, yield
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