Technology of harvesting and storage of grapevine rootstock cuttings

The viability of grafting components and the yield of nursery plants from the nursery bed directly depend on how timely the rootstock vine is harvested and the conditions under which it was stored. Cuttings cut at the optimal time accumulate the maximum amount of nutrients. This ensures rapid fusion of the scion with the rootstock and protects the grape grower from plant losses.

• Optimal diameter of the cutting — 7–13 mm
• Vine humidity before storage — at least 48%
• Storage temperature — about 0 °C (no higher than 2–4 °C)
• Air humidity in the storage facility — 80–85%
• Minimum maturity score for grafting — 6

The timing for harvesting rootstock vines depends on the method of managing the mother plantation. When growing mother plants in a sprawling manner, it is advisable to harvest the vine immediately after leaf fall and complete the work by the end of November. If necessary, cutting can be carried out throughout the winter on frost-free days or in the spring before the sap starts to flow. In mother plantations with supports, the vine is harvested from December to early January, strictly before the onset of severe frosts.

During harvesting, shoots are cut at the very base of the bush, leaving short annual stubs with 3–4 buds on the arms. Before cutting, the vine is cleaned of tendrils, suckers, and thin immature tops with a diameter of less than 6 mm. Shoots are immediately removed from the row spacings and cut into whips 2–2.5 m long. After storage, 3–4, and sometimes 5 standard cuttings 40–50 cm long can be cut from them. The finished vine is sorted by the diameter of the upper section, selecting branches 7–13 mm thick.

Monitoring vine maturity and humidity

The degree of maturity is assessed by the content of starch and sugars in the tissues. At the end of October – early November, when the starch level is at its maximum, 200 shoots are selected from each homogeneous plot of 25–30 hectares. The sample is cleaned of dust and pesticides, washed with distilled water, cut along the node diaphragm, and sorted by the diameter of the upper section using a template with a 0.5 mm increment, forming groups of at least 80–100 pieces.

For analysis, sections 60–80 µm thick are made from the upper part of the cuttings of each group. The sections are kept for 10–15 minutes in a 1% iodine solution, and then the density of starch filling in the cells is assessed under a microscope. The tissues of the medullary rays in the xylem and phloem zone, the perimedullary zone, the libriform, as well as the soft and hard bast are analyzed. The assessment is carried out on a 10-point scale, where 10 points are given for dense filling of all cells, and 1 point — for the almost complete absence of starch grains. Vines with a score of at least 6 points are admitted for grafting.

1. Tie the prepared cuttings into bundles of 100–200 pieces.
2. Attach a label to each bundle indicating the rootstock cultivar and the number of cuttings.
3. Transport the material to the storage location and stack it.

Rootstock cuttings are stored in specialized storage facilities or cellars under the same conditions as scions of European-Asian grape cultivars. The optimal regime provides for a temperature of about 0 °C (no higher than 2–4 °C) and Relative humidity of the air">relative air humidity of 80–85%. Violation of these parameters leads to the desiccation of the vine or premature bud break.