The effectiveness of foliar feeding with Agro.Bio Potassium Humate with urea in dense apple tree plantings

The current stage of industrial fruit growing is characterized by its intensification. This requires, along with agronomic and technical-economic measures, denser planting of fruit trees per unit area. In varying degrees of dense plantings, environmental factors influencing the physiological processes of fruit plants interact differently, determining the nature of these changes in the plant and, ultimately, its productivity. Therefore, studying rational methods of feeding fruit plants and increasing the efficiency of mineral fertilizer use is of particular importance.

Scientific literature indicates that humic acids, as physiologically active substances, directly influence plant metabolism, activating physiological processes and increasing nutrient uptake from the soil. The effects of humic substances when applied in combination with chemical crop protection products have not yet been adequately studied, especially in field conditions.

The concepts of modern Ukrainian and international researchers demonstrate the patterns that determine the action of physiologically active substances, and in particular humic preparations (such as Agro.Bio Potassium Humate ), as well as the common conditions under which the stimulating effect of these substances is particularly noticeable. The main ones include a specific concentration of the stimulant, unfavorable external conditions (primarily elevated temperatures, high nitrogen levels, oxygen deficiency in the root feeding environment, etc.).

Dense plantings of fruit crops are those in which unfavourable external conditions can have a significant aggravating effect, especially during intense temperature and other periods of vegetation.

In foliar feeding aimed at increasing the resistance of fruit crops, we tested the physiologically active preparation Potassium Humate Agro.Bio and urea.

RESEARCH METHODOLOGY

Long-term field experiments studying foliar feeding in combination with pest and disease protection against adequate nutrient supply were conducted in research orchards in the Steppe Zone of Ukraine, with dense tree spacing of 8x8 m (control), 8x6 m, and 8x4 m. The Renet Simirenko, Calville Snowy, and Jonathan varieties were planted as two-year-old seedlings in a trench (60 cm deep, pre-treated with granular superphosphate at 4 c/ha). The rootstock was Borovinka.

The experiment was conducted under dryland conditions in four replicates, with five trees per replicate. The soil was ordinary low-humus chernozem. The orchard was maintained under bare fallow conditions with the addition of organic fertilizers once every three years. Beginning with the full fruiting period, mineral fertilizers were applied annually at a dose of N₆₀ P₉₀ K₄₅ per hectare. During the growing season, 7-8 pesticide sprays were applied against pests and diseases (the control was sprayed with pesticides – background).

Foliar applications of Agro.Bio Potassium Humate and urea were combined with fungicide and insecticide sprays and were performed three times during the growing season: in early June, early July, and late July to early August. The application rate of the working solution was 1,200 l/ha.

RESEARCH RESULTS

When growing gardens in the dryland conditions of the Steppe Zone of Ukraine with dense tree growth, the primary concern is the supply of soil moisture in the layer where the roots are most concentrated.

Table 1. Soil moisture at different planting densities of apple trees, % (beginning of July)

Our research on the water supply of apple tree leaves with foliar feeding with Agro.Bio Potassium Humate and urea in combination with pesticides was conducted during the hottest and driest period of vegetation with low relative humidity.

Table 2. Effect of foliar feeding on the water content in the leaves of growth shoots and rings of the Calville Snowy apple tree (% of fresh weight)

Adding Agro.Bio Potassium Humate and urea to the tank mixture during spraying had a positive effect on the water supply of apple tree leaves. Notably, the highest leaf water content was observed in the experimental variant where humate, urea, and pesticides were applied together.

Table 3. Dynamics of water content in leaves depending on tree planting density (without fertilizing), %

Research results show that foliar feeding increases chlorophyll content and the rate of its production. This is particularly noticeable in the experimental variant using a mixture of Agro.Bio Potassium Humate and urea .

Table 4. The amount of chlorophyll in the leaves of the snow apple tree Calville (mg per 1 g of raw material)

Under unfavorable external conditions, the combined use of humates and urea with foliar feeding is particularly effective in influencing the intensity of photosynthesis.

Table 5. Average daily intensity of photosynthesis of the snowy Calville apple tree

An analysis of the yield of young apple tree plantings showed that it depends on the planting density, the intensity of physiological processes and the area of ​​the leaf surface (Table 7).

Table 7. Removable apple tree yield depending on planting density, c/ha (average for three years)

In order to enhance the intensity of physiological processes and the productivity of trees in dense plantings, along with pruning, an important agricultural technique is foliar feeding with the preparation Potassium Humate Agro.Bio with urea.

Table 8. The effect of foliar feeding on the harvested apple tree yield

The increase in yield resulted in an increase in the size of the fruits and also improved their chemical composition (the amount of soluble sugars and vitamin C increased).

Table 9. Effect of foliar feeding on the chemical composition of fruits (mg per 1 g of raw material)

CONCLUSIONS

Long-term research results show that in fruit-bearing orchards in the Steppe Zone of Ukraine, foliar feeding with Agro.Bio Potassium Humate with urea is highly effective against the background of root nutrition with mineral salts (NPK). By activating metabolic processes, it increases leaf water content, chlorophyll production, photosynthesis intensity, and overall metabolism, ultimately resulting in increased plant productivity and improved fruit quality.

Agro.Bio Expert Note: Today, Agro.Bio specialists continue to develop foliar application technologies based on this fundamental research. The modern formulation of Agro.Bio's Potassium Humate boasts the highest degree of purification and bioavailability, allowing Ukrainian gardeners to achieve consistently high yields even under severe climatic conditions and intensive gardening.