Vine growth balance – Internodal distance and Root:Shoot Relationship
The most significant visible effect of using a vine shelter is the pronounce growth of the leader stem and an increase in the internodal length. The number and strength of lateral shoots reduces to an extent that pruning is not usually necessary in the first year.
As long as there has been good soil preparation there will be good balanced growth between leader length, stem diameter and root growth. Very good root development is experienced that will often support a large crop 18 months after planting.
Root:shoot ratios have been assessed in various trials that indicate a balanced relationship when using all vineshelters. The diameter of the shelter affects the overall relationship, with the wider diameter tubes (80 – 110mm) producing a higher relationship (proportion of root development) of approx 70% after one growing season.
Stem diameter and internodal distance have been measured during various trials and give different results in different locations and with different varieties of vine. Internodal distance can be as much as 100% longer in a vine shelter, compared to a control vine. Stem diameter is less affected, and could be smaller (85%) within a vine shelter, or it could be larger. In trials the longer internodal distance is returns to normal levels once the vine emerges from the shelter.
Lateral growth is caused when the vine plant is buffeted in the wind. It is a stabilization measure adopted by the plant. When the vine grows in a stable, wind-free environment it does not grow laterals. The same is true if the vine is trained up a fixed wooden stake. This is a key difference between a Tubex vineshelter and some of the more flimsy alternatives on the market (plastic films or bags that blow around in the wind).