Grapevine Balance

What is grape vine balance?

Vine balance refers to the equilibrium between fruit growth in proportion to canopy growth. .

Achievng an ideal vine balance entails the maintainance of optimal ratios between fruit clusters, branches, stems , and leaves.

Why is grape vine balance Important?

      Maintaining an ideal balance between fruiting clusters and vegetative growth is important because it has a major impact on final fruit quality parameters (such as sugar content, organic acid composition, fruit size, production volumes, ect)

     For example, if the volume of vegetative growth is too high(with too much wood mass from stems and branches in relation to sun-exposed leaf-surface-area[1]), a large portion of the vines nutrient resources will be utilized for wood development, resulting in a diversion of energy and nutrition away from fruiting clusters. This diversion of nutrients can potentially cause insufficient sugar accumulation in the berries during ripening, plus a smaller final berry size at harvest time as well. 

     Since the amount of sugar and nutrients that one vine can transport is limited, it is important for those resources to be distributed favourably in a way that facilitates a high quality final product. So there needs to be a fine balance between berry cluster density and overall foliage surface area(to permit aeduate exposure of sunlight and photosynthes; to facilitate the production of robust concentration of sugar for each fruit cluster.)

     If the surface area of sun-exposure leaves is not adequate to effectively accommodate their energy requirements[2] through ample photosynthesis, then the supply of sugars will end up being insufficient and will end up being sparsely distributed amongst the berries, resulting in low overall sugar concentrations in the final product. So fruit thinning is often used to enhance final fruit quality[3] in sections of vine which have excessively high berry density

     So, it is important that the vine balance is maintained carefully and attentively, for achieving favorable sugar levels.

     Plus , maintaining an optimal vine balance is also crucial for allowing adequate light exposure to the actual berries(depending on the geographic location) for the enhancement of sugar accumulation during ripening. Plus canopy permeability is also important for permitting sufficient airflow into the canopy.

   Although, in especially intense lighting environments, the degree of exposure does need to be carefully balanced with a strategic positioning of foliage in order to provide shade protection for berries in ordeer to prevent potential sun damage that can occur during peak times of intense midday sun light and uv radiation..

     So, all of  this means that achieving an ideal balance of light, shade, and temperature can ultimately help to improve color, enhance flavor, regulate acidity, increase phytonutrient concentration, and reduce unwanted vegetative aromas in the final product as well.

Which factors are most important for maintaining an optimal grape vine balance?

There are several factors that have significant impact on a growers vine balance:

For instance:

-Cultivar choice: variety, root stock, scion
-Canopy Managment: trellis/pruning/thinning
-Climate: temperature, sun exposure, humidity
-Irrigation: quantity, precision, frequency
-Fertilization: nutrient density, mineral balance

All of which play important roles in the development of a crops vine balance

What actions can be taken to ensure that an optimal grape vine balance is achieved?

Cultivar Choice

    First off, the variety of root stock and the variety of scion should be selected cautiously and chosen with careful consideration of the available environmental growth conditions and their individual genetic physiological tendencies.

     With certain rootstock varieties tolerating specific environmental conditions better[4] than others,(such as climate, temperature, alkalinity, acidity, pests ect) the incorrect rootstock selection that is not suitable for imposing environmental factors can ultimately end up having adverse impact on scion growth potential and vine balance parameters as a whole.

 

     And additionally,  different varieties of scions each contribute their own unique genetic tendencies and attributes[5] as well, with root-stock/scion interactions affecting not only growth potential, but also budding , ripening, fruiting potential, pest resistance, water efficiency, and nutrient uptake; all of which  are crucial to overall  vine balance development and general final product. ,

Canopy Management

    Regardless of the variety type, pruning and thinning strategies are paramount for achieving an ideal vine balance; capable of producing a high quality yield.

   Thinning and pruning techniques can be implemented strategically[6] in accordance with variety requirements and the climate and regions best timing practices.

    For example, pruning intensity should be more aggressive and severe with highly vigorous vine varieties that are growing in very fertile soils holding high moisture levels   

     Furthermore, it is important for growers to adjust their applied canopy management strategies in accordance with any impactful weather patterns and temperature fluctuations, in order to best accommodate the cultivars growth requirements.

     In regions with high amounts of rainfall, pruning should be done early enough in the season to allow for proper wound healing before the onset of excessively wet weather. This can help to decrease the chances of infection and diseases.

     During periods of exceptionally hot weather and intense sunlight, there should be an emphasized focus on strategic trellis structuring techniques along with carefully arranged shoot positioning and leaf foliage covering for achieving optimal sunlight exposure arrangements which best correlate with the suns movement patterns.

      These strategies can be used to control a fruit clusters exposure levels to sunlight( depending on suns positioning and the time of day) allowing the leaves to harness sunlight and redirect energy resources for the purpose of delivering nutrients to fruiting berry clusters rather than wood and other vegetative growth.

     As for fruit thinning strategies, it is important that growers understand the capabilities of their vines and their soils so that they can set realistic expectations and predictions regarding their desired yield and quality parameters, because grape vines do only have a limited capacity for total reproductive growth afterall.

     So, attempting to grow excessively high densities of fruit clusters under inadequate growth conditions can result in inferior fruit quality and insufficient sugar accumulation [7]in the final product at harvest time.   

Irrigation

    In regard to irrigation, since grapevine productivity is significantly influenced by hydration[8] levels and by climatic conditions, ideally,  moisture levels should be monitored frequently in order to accurately apply the most suitable irrigation strategy for each specific situation.

      For example, as a response to heightened temperatures, there should be adjustments made to irrigation applications, in order to compensate for heat stress induced water requirements and increased evaporative demands; caused by amplified plant transpiration and overall moisture loses.

     Likewise, adjustments to irrigation should also be made as a reaction to temperature decreases as well, as over-hydration due to decreased evaporation and transpiration can potentially cause imbalance in the vine too. Because,, excessive water stress will slow overall photosynthesis and divert resources towards wood growth rather than berry development.

  In the case of rainfall and increasing humidity levels, these factors should also be calculated for carefully as well, because failure to incorporate these events into irrigation application schedules could end up resulting in significant unwanted changes in vine balance.

 

Fertilization

     Another very important factor that greatly impacts a vines fruit development is the applied fertilization strategy.

     Too little or too much of any of the essential elements can potentially cause imbalances in the vines overall growth parameters.

     For example, nitrogen levels should be maintained carefully as excessive amounts of nitrogen can potentially cause undesirable increases in uncontrolled wood growth[9] which could ultimately divert resources away from achieving optimal fruit development during ripening. While conversely, insufficient levels of nitrogen can also potentially result in decreased berry sizes and lower overall fruit yield at harvest as well.

     Additionally, potassium levels can also have profound impacts on a growers vine balance too; with inadequate concentrations of potassium causing poor fruit development and excessive potassium concentrations causing unwanted increases in extraneous vegetative growth. 

     And other similar inferences can also be applied towards the other essential minerals and micronutrients as well, such as phosphorus or calcium or magnesium or zinc.

     This is why frequent soil testing and constant monitoring of the cultivated soils mineral concentrations is so important for ensuring high quality yields in each harvest.

References

1.)Janet K. Myers, James A. Wolpert, G. Stanley Howell, “Effect of Shoot Number on the Leaf Area and Crop Weight Relationship of Young Sangiovese Grapevines (2008), American Journal of Enology and Viticulture, DOI: 10.5344/ajev.2008.59.4.422 Effect of Shoot Number on the Leaf Area and Crop Weight Relationship of Young Sangiovese Grapevines | American Journal of Enology and Viticulture (ajevonline.org)

2.) W. M. Kliewer, “Effect of Time and Severity of Defoliation on Growth and Composition of Thompson Seedless Grapes”(1970), American Journal of Enology and Viticulture, DOI:10.5344/ajev.1970.21.1.37, Effect of Time and Severity of Defoliation on Growth and Composition of ‘Thompson Seedless’ Grapes | American Journal of Enology and Viticulture (ajevonline.org)

3.) PETRIE, P.R. and CLINGELEFFER, P.R. (2006), Crop thinning (hand versus mechanical), grape maturity and anthocyanin concentration: outcomes from irrigated Cabernet Sauvignon (Vitis vinifera L.) in a warm climate. Australian Journal of Grape and Wine Research, 12: 21-29. https://doi.org/10.1111/j.1755-0238.2006.tb00040.x

4.) The Science of Grapevines: Anatomy and Physiology, 2nd Editiion (2015) Markus Keller,  Academic Press, ISBN: 9780124199873, The Science of Grapevines – 2nd Edition (elsevier.com)

5.) Paolo Sabbatini & Gordon S. Howell (2013) Rootstock Scion Interaction and Effects on Vine Vigor, Phenology, and Cold Hardiness of Interspecific Hybrid Grape Cultivars (Vitis spp.), International Journal of Fruit Science, 13:4, 466-477, DOI: 10.1080/15538362.2013.789277 Full article: Rootstock Scion Interaction and Effects on Vine Vigor, Phenology, and Cold Hardiness of Interspecific Hybrid Grape Cultivars (Vitis spp.) (tandfonline.com)

6.) M. Carmo Vasconcelos and Steve Castagnoli, “Leaf Canopy Structure and Vine Performa” (2000), American Journal of Enology and Viticulture, DOI = 10.5344/ajev.2000.51.4.390 Leaf Canopy Structure and Vine Performance | American Journal of Enology and Viticulture (ajevonline.org)

7.) C. E. Edson and G. S. Howell and J. A. Flore, Influence of Crop Load on Photosynthesis and Dry Matter Partitioning of Seyval Grapevines. III. Seasonal Changes in Dry Matter Partitioning, Vine Morphology, Yield, and Fruit Composition (1995), American Journal of Enology and Viticulture, DOI= 10.5344/ajev.1995.46.4.478 Influence of Crop Load on Photosynthesis and Dry Matter Partitioning of Seyval Grapevines. III. Seasonal Changes in Dry Matter Partitioning, Vine Morphology, Yield, and Fruit Composition | American Journal of Enology and Viticulture (ajevonline.org)

8.) Junquera, P., Lissarrague, J.R., Jiménez, L. et al. Long-term effects of different irrigation strategies on yield components, vine vigour, and grape composition in cv. Cabernet-Sauvignon (Vitis vinifera L.). Irrig Sci 30, 351–361 (2012). https://doi.org/10.1007/s00271-012-0348-y  Long-term effects of different irrigation strategies on yield components, vine vigour, and grape composition in cv. Cabernet-Sauvignon (Vitis vinifera L.) | SpringerLink

9.) Grapes: Crop Production Science in Horticulture,(2018) 2nd Edition, Glen L. Creasy, Leeroy L. Creasy, Ph.D. ISBN-13: 978 1 78639 136 0  Grapes | Crop Production Science in Horticulture (cabidigitallibrary.org)