The Effect of Fertilisation and Plant Care Practices on the Yield Structure of Black Currant

The article is focused on the influence of fertilisation and plant care on the productivity of the black currant variety ‘Siuita Kyivska’. Black currant was planted on the Rodnikovka Experimental Farm of the Uman State Agrarian University. Better conditions for the development of such signs as the number of clusters per shrub and the length of a cluster were provided under the application of mineral fertilisation as a background and foliar application of fertiliser Riverm 5%, maintaining of interrow space as clean fallow and mulching plants in the row with straw. The best characteristics of clusters were obtained with N 60 P 90 K 90 as background fertilisation. Foliar application of fertiliser Riverm 5% resulted in an increased (by 251.2−299.8) number of clusters per plant and longer (by 0.60−0.80 cm) clusters. A combination of clean fallow and application of Riverm 5% against the background of mineral fertilisation resulted in lower indicators of the fruit weight in a cluster compared to the control. This means that the yield structure of black currant under the effect of fertilisation and plant care changes towards an increase in the number of clusters, thereby reducing the number of fruits and the weight of fruits from one cluster. It was also found that foliar application of fertiliser Riverm 5% against the background of mineral fertilisation contrib - uted to an increase in the yield of black currant. In the treatment with clean fallow between rows and mulching plants in rows, application of fertiliser Riverm 3% or 5% against the background of mineral fertilisation N 60 P 90 K 90 , the yield of fruits was 13.1 t/ha.


INTRODUCTION
Among the biological features of black currant plants, rapid growth should be mentioned since it takes only from 3 to 5 years to obtain a high-yielding plantation, sufficient cold resistance and early fruiting (Hummer and Dale, 2010;Gopalan et al., 2012). At the same time, to obtain a high level of plantation productivity, effective agronomic practices should be applied to care for black currant plants (Heide and Sønsteby, 2012).
In the conditions of Ukraine, it is possible to obtain stable yields of black currant from 9 to 12 t/ha. However, a reason for the low profitability of black currant plantations in Ukraine is the low yield (about 4 t/ha), which leads to the impossibility of effective and environmentally-friendly cultivation of plantations (Markovskyi, 2012;Kopytko et al., 2019). Therefore, the search for ways of improving cultivation technology that could provide a high level of yield and quality of berries is an important task (Hummer and Barney, 2002;Kim et al., 2011).
Among the factors influencing the quality of the produce, fertilisation and plant care can be listed. Due to the lack of mineral components in plant nutrition, it is difficult to obtain highly productive black currant plantations, and in the case of excessive weeds infestation in a row and between the rows is not possible, because crop plants cannot compete with weeds for nutrients, which reduce crop productivity and the plantation becomes unprofitable (Lovell and Johnston, 2009;Malézieux et al., 2009;Opstad et al., 2007;Valladares et al., 2016).
Therefore, the development of efficient methods of fertilisation and plant care is the ground for the formation of high productivity and long-term exploitation of black currant plantations.

MATERIALS AND METHODS
The research was carried out on the Rodnikovka Experimental Farm of the Uman National University of Horticulture (Rodnikovka, Uman district, Cherkasy region).
The black currant variety 'Suita Kyivska' was used in the experiment. It is an industrial medium-early variety known as well-establishing, unpretentious, stable and high-yielding. The berries of this variety are quite large and reach 3.2−3.5 g, with an average weight of 1.7−1.8 g, round-oval in shape, uniform, black, shiny, with elastic strong skin, dry tear, soft greenish-brown flesh, sour-sweet and fragrant. The variety is characterized by the almost simultaneous ripening of fruits. The shrub is of medium height, slightly sprawling, and has elastic shoots and short internodes. Variety is resistant to powdery mildew and rust but can be affected by anthracnose. It is a self-fertile drought-resistant variety that has high processability of the shrub and high, stable yield.
The soil of the plantation was heavy loamy podzol forest chernozem with a humus content of 3.25%. The reaction of the soil solution was slightly acidic with a pH of 5.5, hydrolytic acidity of 2.1 mmol/kg, and a degree of alkali saturation of 92%. The soil of the experimental plantation contained movable compounds of alkaline hydrolysable nitrogen (determined by the Kornfield method) in the amount of 100-110 mg/kg, phosphorus and potassium (determined by the Chirikov method) of 100 mg/kg and 120 mg/kg, respectively.
The experiment was arranged for the study of such plant care options as the maintenance of the soil between rows as clean fallow or grassing with a garden mixture of grass species; maintenance of the soil in rows as clean fallow, mulched with straw or covered with a mulch film; foliar application of fertiliser Riverm at a concentration of 1, 3 and 5%.
Liquid organic bio-fertiliser Riverm contains NPK in a ratio of 10:1:1.5%, trace elements of calcium, magnesium, iron, manganese, copper, zinc, nickel, lead, cadmium, cobalt, microorganisms and nitrogen-fixing bacteria. The fertiliser has a plant-neutral pH of 7−7.4 and is used in the stage of opening leaf buds.
The placement of black currant shrubs in the experiment was 3 m × 0.5 m, with three replications. Ammonium nitrate, granulated superphosphate and potassium chloride were used for fertilisation. To reduce the loss of active components of fertilisers, nitrogen fertilisers were introduced before the beginning of vegetation, while phosphate and potassium fertilisers were applied in the autumn in the near-shrub area.
The methods of establishing and carrying out the experiment, determining crop yield and its structure are described by Prysiazhniuk et al. (2021). To establish patterns and determine the reliability of deviations in the experimental data, a dispersion multivariate analysis was performed using the ANOVA package.

RESULTS
Conditions for the growth and development of black currant differed in the years of research. Therefore, the influence of experimental factors on the formation of the number per branch and the length of a cluster will be analysed separately in the context of the influence of weather conditions during the vegetation season (Table 1).
Weather conditions during vegetation season were the most favourable for black currant in 2019, when, on average, the number of clusters per shrub reached the maximum of 337.7. The least favourable weather conditions were in 2020 when a minimum of 267.5 clusters per shrub was formed.
Clean fallow between rows significantly increases the amount of nutrients available to plants due to the mineralization of the organic component of the soil. Compared with grassing, we obtained 85.1−124.5 more clusters per shrub and 0.4−0.6 cm longer clusters.
If we analyse the options for maintaining the soil in the rows of shrubs, then we can see that clean fallow had the worst effect on the crop productivity indicators, compared to mulching with straw and mulch film. Thus, in the treatment with mulch film, plants had 60.0−84.3 more clusters per shrub and 0.41−0.51 cm longer clusters compared to the treatment with clean fallow. In the treatment with mulching, even higher indicators Fertilisation had a positive effect on the formation of black currant productivity indicators and the effectiveness of the N 60 P 90 K 90 application as a background fertiliser is undoubted. However, with the foliar application of Riverm 5% we obtained 251.2−299.8 more clusters per shrub and 0.60−0.80 cm longer clusters. It can be stated that better conditions for the formation of such yield structure components as the number of clusters per shrub and the length of a cluster ensured treatments with mineral fertilisation and foliar application of fertiliser Riverm 5%, and maintenance of the soil between rows in the state of clean fallow and plant rows mulched with straw.
We also determined the number of fruits per cluster and per shrub ( Table 2).
When analysing the number of fruits per cluster, we observed a reverse trend in comparison with the number of clusters per shrub: in 2019, we obtained 3.1 fruit per cluster and in 2020 4.1 fruits per cluster. At the same time, grassed soil between rows ensured 8−1.1 more fruits in a cluster. On the contrary, the number of fruits per shrub was 70.5−181.8 higher under the maintaining of the soil between rows in the state of clean fallow compared to grassing. Options for soil maintenance in the rows worked similarly. Clean fallow, compared to clean fallow, provided better conditions for the formation of the number of fruits per cluster, while mulch film had a better effect on the number of fruits per shrub. Even better results were obtained for mulching with straw -232.6-270.7 more fruits per shrub.
Data on the weight of fruits from a cluster under the effect of experimental treatments are shown in Table 3.
The highest weight of one fruit was formed in 2020 when a smaller number of fruits per shrub was obtained. It was also found that grassing of the space between rows ensures a 0.4−1.0 higher number of fruits per cluster. Clean fallow and foliar application of fertiliser Riverm 5% against the background of mineral fertilisation resulted in a lower weight of fruits per cluster compared to the control treatments of the experiment. This means that the yield structure of black currant under the effect of fertilisation and plant care changes towards an increase in the number of clusters, thereby reducing the number of fruits and the weight of fruits from one cluster Let us analyse the yield of black currant under the effect of fertilisation and plant care (Fig. 1).
The highest yield of berries (9.0 t/ha) was obtained in 2019, the lowest (7.2 t/ha) in 2020 and average (8.2 t/ha) in 2022. Clean fallow between It is quite natural that foliar application of fertiliser Riverm against the background of mineral fertilisation contributed to an increase in the fruit yield. Therefore, the treatment where clean fallow between rows, mulching plants in rows, mineral fertilisation N 60 P 90 K 90 and foliar application of fertiliser Riverm 3% or 5% were combined yielded in 13.1 tonnes of berries per hectare.
The patterns obtained by us are in agreement with the works of many scientists (Haviuk, 2011;Kucher, 2002;Markovskyi, 2012;Kopytko et al., 2019). They are a logical continuation of the study on the improvement of the cultivation technology of black currant in terms of adaptation to the conditions of the Forest Steppe of Ukraine.

CONCLUSIONS
It was found that better conditions for the formation of such yield structure components as the number of clusters per shrub and the length of a cluster are provided with mineral fertilisation and foliar application of fertiliser Riverm 5% along with maintenance of the soil between rows in the state of clean fallow and plant rows mulched with straw.
The best parameters of a cluster were obtained with the application of N 60 P 90 K 90 as background fertilisation. However, with the foliar application of Riverm 5%, on average in the experiment, we obtained 251.2−299.8 more clusters per shrub and 0.60−0.80 cm longer clusters.
Maintenance of the soil between rows in the state of clean fallow combined with foliar application of fertiliser Riverm 5% against the background of mineral fertilisation results in a lower weight of fruits per cluster, compared to the control. This means that the yield structure of black currant in the context of changes in nutrition and plant care is changing towards an increase in the number of clusters, thereby reducing the number of fruits and the weight of fruits per cluster.
Foliar application of fertiliser Riverm against the background of mineral fertilisation contributes to an increase in the yield of black currant. Clean fallow between rows, mulching plants in rows, mineral fertilisation N 60 P 90 K 90 and foliar application of fertiliser Riverm 3% or 5% yielded 13.1 tonnes of berries per hectare.