For successful vineyard management, it is essential to clearly understand how the grapevine root system develops. Root development, rooting depth, and moisture absorption capacity depend directly on the vine's origin—whether it was grown from a seed or obtained vegetatively from a cutting (sapling). The anatomical and biological features of this process dictate all subsequent agrotechnical practices in the vineyard.

The Root System of a Grapevine Seedling

During the germination of a grapevine seed, its hard, woody shell ruptures. Two longitudinal cracks always initiate at the beak (rostrum) of the seed. Through the resulting aperture, the primary embryonic radicle emerges (Fig. 1). Within a few days, this taproot begins to branch actively. The first lateral roots of the first order branch off directly from the root collar—the junction between the hypocotyl and the primary root.

Following them, in strict succession, the first-order lateral roots begin to branch, giving rise to second-order roots, which, in turn, produce third- and fourth-order roots (Fig. 2 and 3). By the end of the first year of life, the grapevine seedling forms a powerful, ramified root system, striving to encompass the maximum volume of soil.

It is important for the practitioner to know that during the first years of life, the seedling's root system grows and develops significantly faster than its above-ground parts (young shoots). Hybrid seedlings exhibit particularly vigorous development of the underground system.

Adventitious Roots of the Grapevine

In commercial viticulture, growers rarely deal with seedlings. The grapevine is propagated vegetatively because it possesses a natural capacity to readily form adventitious roots. In a natural environment, this capacity manifests as "aerial" roots. In southern regions, after a prolonged and humid spring, the emergence of such roots can be observed on the old, perennial trunks of the vines (Fig. 4). Under ordinary conditions, they quickly perish from desiccation, but in the humid and warm atmosphere of greenhouses, aerial roots develop in entire bundles, reach the ground, and transform into normally functioning lateral roots.

While the appearance of aerial roots requires a rare combination of high humidity and warmth, the rooting of shoots layered in the soil without separation from the mother bush occurs with extreme ease. This technique is called "layering" (otvodki) and is universally used in practice to restore or expand a vineyard.

Patterns of Cutting Rooting and the Three Root Tiers

Planting grapevines using cuttings (chubuks) is the most common method of propagation. The length of the cutting can vary: from a short, single-bud cutting 2–3 cm long to a long cane exceeding 70 cm with 5–6 nodes. However, regardless of the cutting's length, the same biological pattern applies: adventitious roots appear predominantly on the nodes (more precisely, on the lower half of each node) and much less frequently on the internodes. On the internodes, roots typically form in areas of artificial wounding, such as the bottom cut of the cutting.

Thus, exactly as many root tiers are formed on a planted cutting as there were nodes submerged in the soil. The underground part of the cutting is artificially transformed from an above-ground shoot into an underground root axis, fulfilling the role of the primary taproot of a seedling. The main mass of roots is established on the cutting only during the first two years after planting; in subsequent years, the capacity of the root axis to produce new vigorous roots gradually declines.

All adventitious roots developing on a cutting planted in the soil are conventionally divided into three distinct groups based on the site of their initiation:

  • Surface (dew) roots: develop on the uppermost underground node of the cutting, located closest to the soil surface.
  • Lateral roots: form on the intermediate nodes of the cutting, lying in deeper horizons of the soil.
  • Basal (heel) roots: develop from the lowest node of the cutting, directly beneath which passes the bottom cut, known in viticulture as the "heel" (pyatka).

Under normal conditions of cutting rooting, a constant biological pattern always manifests—the more vigorous development of the basal (heel) roots. Lateral roots, as a rule, are characterized by weaker development and are formed in smaller numbers, while the surface dew roots remain the weakest under natural conditions.

The Principle of Polarity and Its Disruption in Practice

Many researchers (Kroemer, in particular) tend to view the vigorous development of basal roots as a manifestation of the natural "polarity" of the grapevine plant. However, in practice, this pattern can easily be disrupted by external environmental factors.

Such disruption is frequently observed during extremely deep planting of cuttings. If the lower node of the cutting enters unfavorable conditions—dense soil with poor aeration, excessive moisture, and low temperature—the development of basal roots is inhibited. In this case, the strongest and most viable roots form not on the heel, but on the middle nodes of the cutting, where the conditions for respiration and soil warming are significantly better.

Furthermore, in viticultural practice, it is customary to perform mandatory "katarovka"—the removal of all surface dew roots during the first years after planting. Because of this artificial operation, it is impossible to determine with absolute certainty under normal conditions whether dew roots always remain naturally weak. When using other methods of training the grapevine (without katarovka), surface roots prove capable of gradually strengthening, thickening, and eventually penetrating into deeper layers of the soil on their own.