Project Number
P04000082
Project title
Effect of in-row vine spacing under high soil potential condition on grapevine performance
Project leader
Hunter, J J
Team members
Hunter, J J
Volschenk, C G
Le Grange, E
Fouche, G W
Adams, L F
Marais, E
EXECUTIVE SUMMARY
Objectives and Rationale
Knowledge of vine reaction to plant spacing under high potential soil conditions is restricted. This project was done to determine effects of vine spacing (with fixed row spacing) of Shiraz/101-14 Mgt on a high potential soil on establishment cost and labour, vine physiological behaviour, growth, yield, and grape and wine quality.
Methods
The project was carried out in Robertson, SA. Shiraz/101-14 Mgt vines were planted during 2008 to a VSP trellis with fixed row spacing of 2.2 m. In-row vine spacing varied from 0.3 – 4.5m with increments of 30 cm (from 15151 – 1010 vines/ha; 0.66 – 9.9 m2/vine). Two bud spurs were equally spaced. Grapes were harvested at two ripeness levels.
Key Results
Total costs, labour and yields showed clear trends, peaking around 1.8 m vine spacing. Root density in fine, extension and permanent categories increased and roots penetrated deeper with narrower spacing. Leaf size increased and trunk circumference, and shoot and cane mass mostly decreased with narrower spacing. Yield: cane mass ratios increased towards wider vine spacing. Fertility and bunch mass increased from narrow to wide spacing. Bunches of narrow spacing treatments were more compact. Sugar levels (°B) and pH decreased and titratable acidity (TA) increased from narrow to wide spacing. With a few exceptions, all sensory descriptors showed decreasing trends from narrow to wide vine spacing in wines from both grape ripeness levels.
Key Conclusion of Discussion
Results indicate a gradual transition from a higher vigour (higher canopy and root density) to a lower vigour (lower canopy and root density) condition, from narrow to wide vine spacing. This led to wider spaced vines having lower leaf:fruit ratios that caused disharmony between increasing spacing and yielding return as well as delayed grape sugar accumulation, ultimately also reflected in the wine composition and sensory profiles. Physiological parameters revealed a complex interplay between vine structure expansion, microclimate, water relations, photosynthetic output, and carbon distribution, most likely comprising unequal development of aboveground and belowground growth; translocation distances; crop load; as well as water and nutrient demands. Balanced development remains essential to minimise erratic grapevine behaviour, beyond normal biotic and abiotic complexities in the field.
Take Home message for Industry
Considering graft material, labour for planting, training and annual management, as well as yields and grape and wine quality, a vine spacing of 1.8 m (approx. 4 m2 surface area/vine) appeared to be optimum under the conditions of this experiment. Although narrower and wider spacing may be plausible under specific circumstances (depending on soil, rootstock, water, fertilization and ambient temperature), vine spacing of less than 1.2m (approx. 2.5 m2/vine) and more than 2.4 m (approx. 5.5 m2/vine) may not be sustainable.
Presentation(s)
Hunter, J J, Volschenk, C G and Strever, A E. 2013. Adapting row orientation and in-row vine spacing to terroir properties. Paper presented at the 35th South African Society for Enology and Viticulture Conference. 13-15 November, Somerset West, South Africa