Application of growth regulators to increase the efficiency of viticulture

The application of growth regulators (phytohormones) is a reliable way to intensify viticulture. These compounds stimulate or inhibit growth processes, helping the agronomist manage the development of the bush at different stages. In practice, they are used to accelerate the rooting of cuttings, improve the healing of grafts, regulate shoot growth, and increase the quality of bunches.

Stimulation of root formation and cutting survival

Treatment with synthetic growth regulators activates the metabolism in cuttings and directs the flow of nutrients to the root formation zone. This accelerates the development of the root system and increases the output of standard nursery plants. To improve the rooting of woody and green cuttings, preparations based on indolebutyric acid (IBA) and indole-3-acetic acid (IAA, heteroauxin) are used.

IBA stimulates root formation more actively, but in practice, heteroauxin (IAA) is used more often as it is cheaper and more economical. In the production of grafted nursery plants, growth regulators solve two problems at once: they improve the union of the scion with the rootstock at the grafting site and stimulate rapid root formation of the rootstock. This allows for a significant reduction in the percentage of culls when digging nursery plants out of the nursery field.

Preparation of planting material requires strict adherence to the sequence of technological operations. Violation of regulations at any of the stages significantly reduces plant survival. Also, the success of the treatment largely depends on maintaining an optimal microclimate.

1. Tie the prepared cuttings into loose bundles of 50 pieces.
2. Immerse the lower ends of the cuttings 2/3 of their length into the working solution of the preparation.
3. Keep the cuttings in the solution for 18–24 hours.
4. Transfer the treated material for callusing.

The success of the treatment depends on compliance with microclimate parameters during the callusing of cuttings:

• Air temperature — 26–28 °C
• Air humidity — 85–90%
• Time in solution — 18–24 h

Regulation of fruiting in seedless cultivars

Gibberellin (gibberellic acid A3) has the strongest effect on fruiting processes. This preparation is indispensable when growing seedless grape cultivars, such as Kishmish Belyi oval, Kishmish Kruglyi, Kishmish Rozovyi, Kishmish Chernyi, and the Korinka group. Due to the absence of seeds, these cultivars do not produce their own hormones for pericarp growth. Foliar treatment compensates for this deficit, allowing for large, marketable bunches.

Treatment of inflorescences at the end of flowering increases the size and weight of berries, increasing the overall yield by 40–50% or more. At the same time, the berries become more resistant to crushing and pressure, which significantly improves their transportability and commercial appearance in both fresh and dried forms. The increased harvest load does not weaken the bushes, as the active influx of nutrients to the bunches stimulates photosynthesis in the leaves.

The working solution of gibberellin can be applied to the inflorescences of seedless grape cultivars in several ways:

• spraying of inflorescences;
• dipping the bunches into the solution;
• applying a hormonal adhesive patch to the bunch stem.

To achieve the maximum effect, it is necessary to strictly observe the dosages of the preparation and the application rates of the working fluid. Foliar treatment is carried out at strictly established developmental stages of the plants. Below are the main technological parameters for the use of gibberellin in vineyards.

• Preparation consumption (80% powder) — 150 g/ha
• Working fluid consumption — 1000–1500 l/ha
• Solution concentration — 100 mg/l
• Yield increase — 40–50%

The effectiveness of gibberellin application has been confirmed by large-scale production experience on an area of more than 2–3 thousand hectares. The technology shows stable results in the main regions where seedless cultivars are grown. The economic indicators of vineyard treatment are shown in the table.

When treating large areas, manual labor is replaced by mechanized spraying. The use of OUM–4 tractor sprayers or upgraded OVT–1V sprayers allows increasing labor productivity by 80–100 times while maintaining high biological efficacy of treatments. This allows work to be carried out within tight agrotechnical timeframes and reduces the cost of production.

Regulation of shoot growth and berry ripening

The effectiveness of treating grape plantations with gibberellin directly depends on the water-nutrient regime of the soil. Due to the sharp increase in yield, the bushes begin to experience an increased need for water and nutrients. To avoid negative aftereffects of the stimulant, it is necessary to strictly maintain optimal soil moisture and apply fertilizer in a timely manner according to the requirements of the Agricultural Guidelines.

• Soil moisture during gibberellin treatment — not lower than 80–85% of field capacity
• Application rate of Tur preparation — 1.2–1.5 l/ha
• Concentration of the working solution for spraying — 0.05–0.1%
• Timing for Tur treatment — 2 weeks before flowering
• Growth inhibition of shoots — by 30–35%

Since the grapevine is a liana with distinct polarity, shoots grow too rapidly under favorable conditions, especially in cultivars of the Eastern ecological-geographical group. Excessive growth of vegetative mass leads to unproductive consumption of nutrients and canopy density. Traditional manual shoot pinching is labor-intensive, so it is advisable to replace it with treatment using growth inhibitors.

In viticultural practice, chlormequat chloride (CCC), known as the preparation Tur (60% aqueous solution), is widely used for this purpose. Its use allows for the redistribution of nutrient flow in favor of reproductive organs, which improves fruit set and increases cluster weight. Treatment provides the greatest yield increase in cultivars with loose clusters, while simultaneously enhancing the photosynthetic productivity of plants through the synthesis of chlorophyll "b".

To accelerate harvest ripening and sugar accumulation in berry juice, it is promising to use ethylene-producing preparations. They also reduce the attachment strength of berries to the pedicel. This technique facilitates mechanical harvesting by shaking and reduces berry damage during collection.

Soil management and tillage systems in vineyards

Proper soil care determines the general condition of plantations and allows for obtaining a harvest of specified quality. The tillage system must address the tasks of moisture conservation, improvement of aeration, fertilizer application, and control of weeds. In zones of cover viticulture, tillage helps protect vines from winter frosts, and in irrigated viticulture — to rationally use irrigation water.

To avoid destruction of the soil structure and reduce farm expenses, the number of machinery passes through the vineyard must be limited. Tillage timing should be strictly coordinated with weather conditions, soil moisture, and the general technological schedule for vine care. Sodding, sowing green manure crops, using herbicides, and combining several operations in a single pass of the unit help to optimize labor costs.

To reduce soil compaction and save resources, it is recommended to use the following combined technological practices:

• simultaneous fertilizer application and irrigation during periodic plantation trenching or deep soil loosening;
• combination of autumn ploughing in row spacings with hilling of grapevines.

Soil management systems: sodding and green manuring

In zones of cover viticulture, where vines are annually covered with an earthen mound for the winter and uncovered in the spring, bare fallow remains the basic management system for the soil. Green manure crops are sown here only in isolated cases when water availability is high. In non-cover zones, the choice of technology is wider and depends primarily on moisture availability. With good natural moisture or under artificial irrigation, vineyard row spacings are sodded or occupied by green manure crops.

Good results are obtained by sowing winter crops and cutting their root system in late April — early May to a depth of 12–15 cm. Annual and perennial grasses are also used, which play a key role in protecting the soil from erosion on slopes. Sodding is usually carried out only in bearing vineyards.

Grasses are sown in a strip 1–1.5 m wide, leaving a clean strip near the rows for subsequent soil tillage. In the second and subsequent years, the grass stand is periodically mowed with KIR-1.5 or KFN-1.6 mowers, leaving the mowed mass in the row spacings as mulch. After 3–5 years, the strips are ploughed, moving the sodding to adjacent row spacings. On steep slopes, permanent strip-sodding is permitted.

The scheme of grass sowing in row spacings depends directly on the slope steepness:

To create a sod cover, pure grass sowings or grass-legume mixtures are used. Spring sowing is carried out in late March — early April. However, the best time for sowing grasses is considered to be early autumn — the second half of August or September. The most promising option for slopes is the combination of strip-sodding in row spacings with herbicide application in the rows.

• Width of the grass strip — 1–1.5 m
• Root pruning depth for winter crops — 12–15 cm
• Ploughing interval for grass strips — every 3–5 years
• Timing for autumn sowing of grasses — second half of August — September

For grassing vineyards, the following crops are recommended:

• Grasses: meadow fescue, perennial ryegrass, orchard grass, tall oat-grass, rhizomatous wheatgrass, Kentucky bluegrass, crested wheatgrass, timothy-grass, smooth brome, meadow foxtail.
• Legumes: white clover, red clover, Caucasian sainfoin, perennial lupine.
• Intra-row space: low-growing grasses (perennial ryegrass) or low-maintenance lawn grass mixtures that do not require mowing.

Tillage: autumn ploughing and spring moisture conservation

Vineyard soil is tilled almost throughout the entire year. During the dormant period of the grapevine, the main task of the agronomist is to accumulate and conserve moisture from rain and snow. In autumn, after harvesting (and in the cover zone — after pruning and covering the vines), deep ploughing with furrow turning is performed. Ploughing in the "open" method provides the best results during this period.

Ploughing in the "open" method moves the soil layer toward the vine bush area, which suppresses the development of winter weeds and reduces the number of manual weedings. At the same time, the top pulverized soil layer, 0–10 cm thick, is buried, while the lower, more structured layer ends up on top. This allows maintaining the water stability of aggregates in the top layer throughout the year at a level of 43–48%.

In contrast, annual autumn chiselling or deep loosening without moving layers reduces the water stability of the structure to 33%. According to the soil structure classification, such indicators bring it close to a structureless state. Spring tillage, in turn, focuses on maximizing the conservation of accumulated moisture and protecting against weeds.

On sunny days, moisture loss through evaporation reaches 4–6 mm per day. Loosening and harrowing the top layer prevent moisture from rising to the surface, create a mulch, and reduce evaporation by 1.5–2 times. Moisture loss is heavily influenced by topography: on uneven plots, evaporation increases by 15–30%. Therefore, spring tillage should consist of shallow loosening followed by leveling and rolling of the top layer.

For early spring tillage in vineyards, cultivation to a depth of up to 15 cm is best. On compacted soils, chiselling to a depth of up to 30 cm is performed. Both operations are carried out with simultaneous tillage between the vine bushes.

• Moisture loss to evaporation on sunny days — 4–6 mm per day
• Reduction in evaporation after loosening — 1.5–2 times
• Increase in evaporation on uneven plots — by 15–30%
• Spring cultivation depth — up to 15 cm
• Chiselling depth for compacted soils — up to 30 cm

Summer tillage in vineyards aims to conserve moisture after rains and irrigation, control weeds, and restore the loose state of the top layer after technological operations for vineyard maintenance have been completed. For this purpose, cultivation to a depth of up to 15 cm is used. In the zone of irrigated viticulture, vineyard maintenance practices also include cutting irrigation furrows or slits, followed by their closing after irrigation once the soil has reached the proper moisture content for tillage. All these operations are performed using the PRVM-3 machine with the appropriate set of attachments.