Prospects for the use of planting tubers 10-15 mm when growing potatoes for a healthy diet

Perspectivas para o uso de tubérculos de 10-15 mm no cultivo de batatas para uma dieta saudável

Abstract

The results of studies conducted in the period of 2019-2021 in order to determine the effectiveness of growing high-quality food potatoes saturated with trace elements for a healthy diet. The field test was launched according to the available procedures on the territory of the Korenevo (Kraskovo) experimental station in the Moscow region on the sod-podzolic medium-cultivated, granulometric composition sandy loam soil. Sprouted small fraction mini-tubers of 10-15 mm in size and 3 to 5 g in weight of the following varieties were planted: Gulliver (early ripening (ER)), Ametist and Grand (medium early ripening (MER)). The research years – 2019, 2020 and 2021 – were characterized, respectively, as humid, very humid and slightly arid. The average yield for all varieties was 18.0 t/ha, including commercial tubers in size – 96.5 to 97.4%, or 67-91% of the possible potential yield, depending on the variety. The starch content in tubers was within the range of potentially possible values, namely, in Grand (16.5 to 18.3%). The nitrate content in potato tubers of all varieties did not exceed MPC – 250 mg/kg. Tubers of all varieties turned out to be quite tasty – 6.0 to 7.5 points, Gulliver tubers (7.5 points) being found the most delicious, despite the low starch content. Selenium content in tubers when applying sodium selenite in average for three years was 0.040 to 0375 mg/kg, which does not exceed MPC in potatoes (0.5 mg/kg). The obtained data provide grounds for expanding research not only to correct selenium deficiency in ecosystems, but also to increase yields and improve the quality of agricultural products. Potatoes were sold at a price of 17 rubles/ kg, the income from potato cultivation amounted to 21.7 to 104.0 thousand rubles/ ha, and profitability was 16.1 to 28.6%. The research has proved the economic feasibility of producing food potatoes grown in the field from mini-tubers of small fractions obtained using the aero-hydroponic method with a compound nutrition system.

Keywords:
potatoes; non-standard mini-tubers; sodium selenite; yield; quality of tubers; starchiness; darkening of the pulp of tubers; profitability

Resumo

Os resultados de estudos conduzidos no período de 2019 a 2021 visam determinar a eficácia do cultivo de batatas de alta qualidade, ricas em oligoelementos, para uma dieta saudável. O teste de campo foi iniciado de acordo com os procedimentos disponíveis no território da estação experimental de Korenevo (Kraskovo), na região de Moscou, em solo franco-arenoso de composição granulométrica, médio-cultivado e podzólico. Foram plantados minitubérculos germinados de 10-15 mm de tamanho e 3 g a 5 g de peso das seguintes variedades: Gulliver (maturação precoce), Ametist e Grand (maturação semiprecoce). Os anos de pesquisa – 2019, 2020 e 2021 – foram caracterizados, respectivamente, como úmidos, muito úmidos e ligeiramente áridos. A produtividade média para todas as variedades foi de 18,0 t/ha, incluindo tubérculos de tamanho comercial – 96,5 a 97,4%, ou 67-91% do potencial produtivo, dependendo da variedade. O teor de amido nos tubérculos estava dentro da faixa de valores potencialmente possíveis, nomeadamente, na variedade Grand (16,5 a 18,3%). O teor de nitrato nos tubérculos de batata de todas as variedades não ultrapassou o Limite Máximo Tolerado (LMT) – 250 mg/kg. Os tubérculos de todas as variedades mostraram-se bastante saborosos – 6,0 a 7,5 pontos, sendo os tubérculos da variedade Gulliver (7,5 pontos) considerados os mais saborosos, apesar do baixo teor de amido. O teor de selênio nos tubérculos, após a aplicação de selenito de sódio em média durante três anos, foi de 0,040 a 0,375 mg/kg, o que não ultrapassa o LMT para batatas (0,5 mg/kg). Os dados obtidos fornecem subsídios para a expansão da pesquisa, não só para corrigir a deficiência de selênio nos ecossistemas mas também para aumentar a produtividade e melhorar a qualidade dos produtos agrícolas. As batatas foram vendidas a um preço de 17 rublos/kg, a renda do cultivo da batata foi de 21,7 a 104,0 mil rublos/ha e a lucratividade foi de 16,1 a 28,6%. A pesquisa comprovou a viabilidade econômica da produção de batata alimentícia cultivada no campo a partir de minitubérculos de pequenas frações obtidos pelo método aero-hidropônico com sistema de nutrição composto.

Palavras-chave:
batata; minitubérculos não padronizados; selenito de sódio; rendimento; qualidade dos tubérculos; amido; escurecimento da polpa dos tubérculos; rentabilidade

1. Introduction

The nutritional value of potatoes is largely determined by the balanced ratio of the most important nutrients (starch, protein, fats, vitamins, minerals, organic acids, etc.) in tubers. Producing consistently high yields, potatoes seem to be a highly productive agricultural crop of the temperate zone.

In recent decades, commercial potato cultivation in Russia has declined significantly. In many regions, there has been a tendency to increase potato yields in the sector of agricultural enterprises and household farming units and decrease production in the sector of private subsidiary smallholdings. It is relevant to maintain the total volume of potato production at a level that meets the population needs in the Russian Federation (Starovoitova et al., 2021).

Russia ranks third in the world in terms of gross potato production after China and India. In 2020 the structure of the acreages occupied by potatoes consisted of 76.2% for households (HH), about 13% for agricultural (farm) organizations (A(F)O), 10.8% for peasant (farm) enterprises (P(F)E) (Russia, 2021a, b). As part of the implementation of the departmental project ‘Development of agro-industrial sector that provide accelerated import substitution of the main types of agricultural products, raw materials and food’ within the State Program for the Development of Agriculture and regulation of markets for agricultural products, raw materials and food in 2019, 22.1 million tons of potatoes were produced by A(F)O and P(F)E, among them 7.6 million tons produced by individual entrepreneurs (Russia, 2020).

In 2020 potato production on farms of all types in the Russian Federation amounted to 19.6 million tons (including 6.8 million tons in A(F)O and P(F)E), that is 11.3% less than in 2019. The yield was 166 kg/ha, or 93.3% in comparison to 2019. The average annual potato production was 22.8 million/t for the period 2015- 2019 provided that crop capacity was 167 kg/ha (Russia, 2021a, b).

Currently, there is a lack of own seed material in the potato farming industry. Due to the purchase of seed material abroad, new potato diseases and pests that are not typical for Russia appeared. One of the main tasks in crop cultivation is to deepen research on the methodology of managing the crop yield and product quality (Shabanov et al., 2019).

One of the main problems is the increasing frequency of climatic variations, consisting of prolonged droughts during the growing season and heavy rainfall during potato harvesting, which results in poor yields (Russia 2019). In 2019, direct damage from natural disasters in the agriculture in Russia amounted to 13.17 billion rubles.

The development of organic potato cultivation technology is relevant now.

In traditional seed production industry, technologies of clonal micro-plant reproduction in vitro with further production of mini-tubers under controlled environment are widely used (Malko et al., 2011).

Aeroponic production of certified seed potatoes is a rapidly developing alternative for arid and semi-arid areas where there is not enough fresh water, and soil-borne diseases and nematodes prevent cultivation in the fields (Silva Filho et al., 2022).

Considerable attention has been paid to modern methods of growing plants under the conditions of aero-hydroponics based on the oxygenation of water by passing it through the air (Popkova, 2022). Historically, agriculture in many countries has been one of the leading industries, hence the introduction of innovations and investment in this area is considered to improve significantly the economic situation of the Russian Federation (Fussy and Papenbrock, 2022). Various farm and forest crops are grown in plant hydroponic units: leaf lettuce, Daikon, tomatoes, potato mini-tubers (Khutinaev et al., 2016), Jerusalem artichoke, arum, medicinal plants, odoriferous herbs, juniper, prickly spruce, forage crops. Moreover, different nutrient media (Varia et al., 2022), lipid metabolism (Wang et al., 2022), accumulation of anthocyanins and phenolic acids and antioxidant activity (Oleinits et al., 2022) are studied.

Currently, producers of original potato seeds are interested in using highly efficient production methods based on the use of aero-hydroponic cultivation technologies. The latter make it possible to prolong tuber formation and obtain successful development of mini-tubers more than 10 g in size (Khutinaev et al., 2016). The possibilities of increasing the number of tubers from one plant by the aeroponic method of cultivation have been shown. Nowadays, the method of plant cultivation in indoor structures equipped with a compound nutrient system has been found to be the most cost effective per unit of total factor input. Such technological process ensures a yield of over 57 potato mini-tubers with a size of more than 10 mm (tubers with a size of less than 10 mm were not taken into account) from one plant with the lowest direct energy costs (Khutinaev et al., 2016).

The conducted studies on the potato cultivation from mini-tubers of different sizes have showed that all tested varieties had lower productivity in greenhouses compared to the crop cultivated in the field (yield differences were from 0.74 to 10.29 t/ha), but their tubers were of better quality according to phytosanitary indicators, being 100% free from viruses. The fraction with a size of 25 to 35 mm gave a higher yield compared to the fraction with a size of 15 to 25 mm (Nistor et al., 2011). Mini-tubers of these fractions (15 to 25 and 25 to 35 mm) are widely used in the original potato seed production to obtain healthy seed material for further replication of varieties. Mini-tubers with a size of less than 15 mm are rejected in seed production as nonacceptable. Hence, it seems promising to use small mini-tubers when growing healthy, high-quality food potatoes saturated with trace elements.

The widespread occurrence of microelemental diseases and their significant impact on the health of the world's population determine the need to develop effective measures to optimise the supply of human population with microelements. Selenium (Se) belongs to a group of seven elements (Fe, Ca, Mg, I, Se, Zn, Cu), the deficiency of which is the most widespread among the inhabitants of the planet (White and Broadley, 2009). This is especially true for a significant part of the territory of Russia, where the population has registered levels of selenium in blood serum less than 75 µg/l with the norm of 115 to 120 µg/l according to Golubkina and Sokolov (2012).

Low selenium content in soil is observed in China, Sweden, and Finland; in Russia, this is characteristic of the Republic of Buryatia and the Chita Region. A number of Western European countries, the USA and China have adopted state programmes stimulating the production of food additives for humans and animals. Fertilisers enriched with selenium are used in Finland, New Zealand, China, and the USA to obtain selenium in the food chain and as an alternative to direct selenium feed additives (Kulchitskiy and Naumov, 2015). This application of selenium is growing (BGS, 2014). In the long term, the role of selenium and Se-containing compounds will increase due to the development of new innovative application sectors. By 2030, the global demand for selenium may grow to 8-9 thousand tons/year (Kulchitskiy and Naumov, 2015).

Selenium is a powerful immunomodulator and a natural antioxidant, effectively protecting the body from various kinds of stress. It is essential for growth, normal functioning of the brain and reproductive system of the body. The importance of selenium for normal thyroid metabolism is well known (Kulchitskiy and Naumov, 2015).

The possible ways to solve the problem of trace element deficiencies include: expanding the range of applied food products, enriching finished food products with trace elements, using biologically active additives, and biofortification of agricultural plants. The last way seems to be the most promising and economically favourable, capable of covering a large part of the population regardless of the place of residence and social status. The use of selenium in the form of sodium selenite in fertilisers, food, and vitamin supplements has increased over the last 5 years, as its benefits for human health are widely recognised (Kulchitskiy and Naumov, 2015).

The main method of solving the problem of selenium deficiency is agrochemical - the use of Se-containing fertilisers.

Currently, Se-enriched garlic (USA), tomatoes (UK), and tea (China) are produced on an industrial scale. In Finland, NPK fertilisers enriched with sodium selenate have been widely used since 1985 (Ekholm et al., 2007). In Russia, the technology of obtaining Se-enriched sweet pepper has been developed (Golubkina et al., 2010) and the preparation was successfully tested on patients with cardiovascular diseases at Khabarovsk Medical University.

However, there are serious problems in the implementation of Se-enrichment technology in plants. First of all, it is low resistance of most agricultural plants to high concentrations of the trace element. In addition, the optimum Se-concentrations used for biofortification may differ significantly for different plant species. There are also varietal differences, although less pronounced.

Thus, the enrichment of agricultural land will provide plants with necessary micro- and macroelements, improve the quality of agricultural raw materials for the production of high-quality food products (Shchukin et al., 2018). Scientists emphasise the relevance of food enrichment with selenium, so purposeful research in this area has been intensified in recent years (Amagova and Golubkina, 2018).

Therefore, it is necessary to survey cultivation of food potatoes of proper high-quality in the open ground from mini-tubers of a fraction 10 to 15 mm in size alongside with leaf treatment with a selenium-containing preparation and with laboratory studies on the crop suitability for food.

To minimize costs of mini-tuber production remains an urgent task for scientists to develop new effective cultural practices in order to get original seed material, including selenium-rich food-grade tubers for dietary purposes.

The purpose of the research was to determine the effectiveness of growing high quality food potatoes, saturated with the trace element of selenium for a healthy diet, in the field from outsized small fraction mini-tubers.

2. Materials and Methods

Scientific methods such as physical modeling, analysis and synthesis were used in the study.

The research was carried out on the territory of the experimental center Korenevo (Kraskovo), Moscow region, in 2019-2021 on the sod-podzolic medium-cultivated, granulometric composition sandy loam soil. The field experiment was laid down in accordance with the available methodology (Dospekhov, 1985) according to the scheme, by the method of systematic placement of plots in fourfold replication with a planting density of 44.4 thousand plants/ha with a row spacing width of 75 cm to a depth planting of 8...10 cm. The area of the test plot was 21 m².

In autumn, underwinter plowing was carried out with a revolving plow to a depth of 18 to 22 cm. In spring, for pre-planting seedbed preparation soil tillage was done to a depth of 12 to 15 cm by means of a machine-tractor unit with a disk heavy harrow. Fertilizers were applied locally as part of the ridge-forming tillage before planting (N40P40K70) and during the period of crop tending (N40P40K40) by a machine-tractor unit with a row cultivator (background).

Test variants were planted in ridges formed with a unit quipped with a hand-feed potato planter. Sprouted small fraction mini-tubers of the following potato varieties were used (the size of tubers in the largest cross section was 10-15 mm, the tuber weight was 3 to 5 g): early-ripening Gulliver, medium-early-ripening Ametist and Grand.

Described below is the experiment procedure. Sodium selenite (98.7%) at a dose of 0.01 g/l was selected as a selenium-containing preparation. The plants of the experimental variants were treated at the sprouting phase (a plant height of 10-15 cm).

Herbicides (a systemic pesticide in the phase of full germination) were used to control weeds. A one-time insecticide spraying was used to control pests (Colorado beetle). Two treatments were performed with a fungicide – a contact pesticide – to control the main diseases (late blight and alternariasis). All agents were applied in the dose recommended by the manufacturer. The spray material consumption was 300 l/ha. In 2019, 2020, and 2021, basic characteristics of the growing seasons from May, 1 to August, 31 were:

• average air temperature – 17.4 °C, 17.1 and 19.7 °C, respectively (at the rate of 16.5 °C);

• precipitation was sufficient for growing potatoes without additional irrigation – 292.3 mm (112.2% from the norm), 427.1 mm (163.95% from the norm) and 258.0 mm (99.04% from the norm);

• the sum of effective temperatures (above 10 °C) – 2126.18 °C, 1980.04 °C and 2354.61 °C, respectively;

• hydrothermal index – 1.38 (wet year), 2.1 (very wet year) and 1.096 (slightly arid year).

Mini-tubers were cultivated in aero-hydroponic devices at the laboratory of the Russian Potato Research Centre named after A.G. Lorch, equipped with a combined aero-hydroponic power system. To grow mini-tubers of potatoes, an aero-hydrophone module with four sections of 40 seats, arranged according to the 90 × 200 mm scheme, with a total area of 2.88 m² was used.

The harvesting of mini-tubers began 60 days after planting. It was done every 7 days after tubers reached the size of 10 to 15 mm in diameter when they became the potential to germinate that is why we harvest them.

The collected mini-tubers were dried indoors for 3 days, and then they were exposed to light to turn green at room temperature for 3 to 5 days.

Further preparation for long-term storage (from September till May) was carried out using traditional storage technology.

We have previously grown mini-tubers on aero-hydroponic plants. During the growing season, the total yield of mini-tubers with a size of 10-15 mm was more than 100 pieces per 1 plant.

During the growing season, we made the following records and observations in field conditions: gross and marketable yield (August 28th - September 03); study of tuber quality indicators. The average potential commercial yield of potatoes obtained from the catalogues of potato varieties starch and dry matter content (by the weight method), nitrate content in tubers (ionometrically), selenium content in tubers (Starovoitov et al., 2024), and flesh darkening of raw and cooked tubers (Gordeev and Udalova, 2017).

3. Results

3.1. Yield of potatoes grown from mini-tubers of small fraction

The main criterion for evaluating the field work performed is the yield, which, as is known, depends on the meteorological conditions of the year and the varietal characteristics of the crop (Table 1; Figures 1 and 2).

Table 1
The plan for conducting experimental studies.

Variety	Yield, t/ha				Marketability,%	Potentially possible croppage, t/ha	± extra potentially possible croppage
	Research year			Average for 2019-2021
	2019	2020	2021				t/ha	t/ha
Ametist, control	15.2	15.3	14.8	15.1	97.2	22.5	7.4	67.1
Ametist, experiment	16.5	17.3	15.1	16.3	97.3		6.2	72.4
Grand, control	18.2	17.1	17.6	17.6	96.5	25.1	7.5	70.3
Grand, experiment	18.5	21.9	19.4	19.9	96.7		5.2	79.4
Gulliver, control	18.4	19.8	17.6	18.6	97.1	22.3	3.7	83.4
Gulliver, experiment	20.7	21.0	19.2	20.3	97.4		2.0	91.0
Average	17.9	18.7	17.3	18.0	97.0	23.3	-	-
НСР05	1.72	2.34	1.79	-	-	1.28	-	-

Figure 1
Yield of Grand commercial potato tubers grown from small mini-tubers obtained by aerohydroponics, t/ha. Note: Average value by variety, 2019 – 17.6 t/ha, LSD ₀₅ (2019) – 1.65 t/ha. Average value by variety, 2020 – 18.0 t/ha, LSD ₀₅ (2020) – 2.24 t/ha. Average value by variety, 2021 – 16/6 t/ha, LSD ₀₅ (2021) – 1.69 t/ha.

Figure 2
Crop yield of market and non-market fraction of potato tubers grown from mini-tubers obtained by the aero-hydroponic method and potential market product yield of varieties, t/ha (on average for three years).

3.2. Qualitative and economic characteristics of potatoes obtained from mini-tubers

Figure 3 shows the results of measuring the starch content in grown tubers.

Figure 3
Content of moisture, dry matter and starch in potato tubers grown from small fraction mini-tubers obtained by aero-hydroponic method, average potentially possible data and empiric data for 2019-2021. LSD₀₅ (2019) - 1.63%; LSD₀₅ (2020) - 1.45%; LSD₀₅ (2021) - 0.92%.

We also studied the nitrate content in tubers, mg/kg (Figure 4), and tuber flesh browning (Figure 5), evaluated taste qualities of potato tubers produced (Figure 6) and carried out an economic assessment of potato cultivation from small fraction mini-tubers obtained by the aero-hydroponic method (Figure 7).

Figure 4
Nitrate content in tubers, mg/kg. (average for 2019-2021). LSD₀₅ (2019) - 23.16 mg/kg; LSD₀₅ (2020) - 14.96 mg/kg; LSD₀₅ (2021) - 25.74 mg/kg.

Figure 5
Browning of tuber flesh, points, (average for 2019-2021). Browning of the tuber flesh: 1 – browns very much; 3 – browns strongly over the entire surface; 5 – browns moderately; 7 – browns slightly; 9 – does not brown. Browning of raw tuber flesh: LSD₀₅ (2019) - 0.97; LSD₀₅ (2020) - 1.05; LSD₀₅ (2021) - 0.77. Browning of boiled tuber flesh: LSD₀₅ (2019) - 0.96; LSD₀₅ (2020) - 0.29; LSD₀₅ (2021) - 0.33.

Figure 6
Taste boiled tuber pulp, points, (average for 2019-2021). Browning of the tuber flesh: 1 – browns very much; 3 – browns strongly over the entire surface; 5 – browns moderately; 7 – browns slightly; 9 – does not brown. Taste of boiled tuber flesh: LSD₀₅ (2019) - 0.11; LSD₀₅ (2020) – 0.25; LSD₀₅ (2021) - 1.41.

Figure 7
Selenium content in tubers, mg/kg of raw weight in the feedstock.

Figure 7 shows the results of measuring selenium content in grown tubers.

We have calculated economic efficiency (Figure 8).

Figure 8
Economic efficiency of growing food potatoes from small fraction mini-tubers obtained by the aero-hydroponic method, average for 2019-2021.

4. Discussion

4.1. Yield of potatoes grown from small fraction mini-tubers

In 2019, the average yield for all tested varieties was 17.9 t/ha, in 2020 – 18.7 t/ha, in 2021 – 16.2 t/ha, respectively (Table 1). At the same time, the commodity size of tubers in 2019 turned out to be 97.9 to 99.1%, in 2020 – 95.2 to 97.0%, and in 2021 – 95.2 to 96.7%, that affected the yield of tubers of marketable size, the latter averaged 17.6 t/ha, 18.0 and 16.6 t/ha, correspondingly (Figure 1). According to the standard, the size of tubers along the largest transverse diameter should be at least 30 mm for round-oval tubers and 28 mm – for elongated ones. Consequently, taking into account the size of the seed tubers, all growing seasons were very favorable for producing potatoes from mini-tubers and obtaining a fairly high yield.

On average for three years (Table 1, Figures 1 and 2), the early Gulliver variety showed the highest yield; total (gross) yield was 19.5 t/ha and marketable in size yield was 18.9 t/ha by maximum transverse diameter of more than 30 mm. The lowest yield was noted in the early-ripening variety Ametist: total (gross) and marketable in size - 15.7 and 15.3 t/ha, respectively. The use of sodium selenite resulted in the yield increase of marketable tubers, which averaged 0.9 to 2.6 t/ha over three years.

In previously conducted experiments in seed germination control on fertile soils by Anisimov et al. (2017), the Nevsky variety with a fraction of 1-5 g produced 397 g/bush from mini-tubers. According to averaged data, we received 317 to 446 g/bush in our experiments that indicates the possibility of obtaining higher yields from mini-tubers under favorable conditions.

Mini-tubers weighing 1-5 g with a planting density of 95.2 thousand pcs./ha produced 18.0 to 20.1 t /ha, and in the experiment with a density of 71.4 thousand pcs./ha the yield was18.3 to 24.3 t/ha (Krychkovsky, 2009). It also confirms the possibility of obtaining high yields of potatoes from mini-tubers of small fraction for food purposes.

According to the characteristics given by breeders, the average potential commercial yield of potatoes grown from mature elite seed tubers was:

Ametist – 22.5 t/ha (Russia, 2022a);

Grand – 25.1 t/ha (Russia, 2022b);

Gulliver – 22.3 (Russia, 2022b).

In our experiments, the following indicators of gross yield by varieties (t/ha, or % of possible potential yield) were obtained:

Ametist – 14.8 to 15.3, or 66 to 68%;

Grand – 17.1 to 18.2, or 68 to 73%;

Gulliver – 17.6 to 19.8, or 79 to 89%.

These values point that under favorable conditions more than 66-89% of the potential yield can be obtained from mini-tubers of a small fraction grown by the aero-hydroponic method, depending on the variety.

4.2. Qualitative and economic characteristics of potatoes obtained from mini-tubers

As for food potatoes both yield values and qualitative characteristics (the content of dry matter and starch in tubers) are important, the latter are primarily determined by the biological features of the variety, and can also vary significantly from growing conditions. Dry matter content in tubers affects the product yield and is an indicator of the suitability of potatoes for processing: the more dry matter in potatoes, the better the quality of processed products (taste, crispy properties, friability). The dry matter content in tubers for the food production should be at least 20% (20 to 24%) (Pshechenkov et al., 2018).

The data obtained in the experiment (Figure 3) has shown that tuber starchiness of the Ametist (12.5 to 14.9%) and Gulliver (10.8 to 14.0%) varieties was slightly lower than their varietal characteristics allow – 15.0 to 16.0% and 14.1 to 15.4%, respectively. The starch content in tubers of the varieties Grand (16.5 to18.3%) was within the range of potentially possible values –13.4 to 18.0%. It proves full physiological maturity of tubers for food consumption.

In tubers of the Ametist and Gulliver varieties, dry matter content turned out to be less than 20%, therefore, tubers of these varieties are better for salads and cutting. The highest dry matter content was found in tubers of the Grand variety – 21.8–23.1 to 23.5%. Hence, tubers of this variety should be used for further processing, for example, for dry puree production. The application of sodium selenite had no significant effect on the starch and dry matter content in tubers.

One of the main indicators of grown product quality is the amount of nitrates in potato tubers. A lot of factors are known to affect the nitrates entry into the soil and their accumulation in plants, one of them is the use of nitrogen fertilizers. At the same time, it should be considered that NO3 ion concentration in tubers may be influenced by varietal characteristics, stressful situations, prevailing conditions of the growing season (in terms of moisture availability, temperature, daylight time, etc.).

According to the experiments conducted (Figure 4), nitrate content in potato tubers changed depending on the meteorological conditions of the growing season. In 2020, nitrate content in tubers was 32 mg/kg, on average less than in 2019, while in 2021 it was 38 mg/kg higher than in 2019, which confirms the dependence of this indicator on meteorological conditions of the growing season. The application of sodium selenite had no significant effect on the nitrate content in tubers. At the same time, it did not exceed the maximum permissible concentration (250 mg/kg) in all varieties. Consequently, potato tubers grown in the field from small fraction mini-tubers obtained using aero-hydroponic units with a combined nutrition system can be used for food potato production.

One of the quality indicators of food potatoes is flesh browning. It is vital that potatoes do not start turning brown in a few minutes after they are peeled or cooked. According to our findings, raw tuber flesh of the Gulliver variety was less susceptible to browning compared to tubers of other varieties. Tubers of this variety became slightly brown along the edge near the peel 24 hours after cutting. It was valued by 7.8 to 8.3 points in all years of the research. Tubers of this variety can be vacuum-processed or frozen for long-term storage in a purified form. Tubers of varieties Grand with light bodies turned out to be moderately brown in 24 hours after cutting. They were appraised by 5.8 to 6.8 points. Therefore, potato tubers can be used for food purposes, but it is desirable to put them immediately after peeling in water or solution, which is usually done by housewives. Tubers of the Ametist variety were not evaluated, since their flesh colour is originally purple. In general, it can be concluded that tubers of all varieties can be used for food purposes (Figure 5).

Being evaluated 24 hours after cutting and cooking, both tested varieties received high points, so they may be recommended for cookery purposes. At the same time, tubers of all varieties turned out to be ’slightly overcooked’ or almost ‘not overcooked’. Their points were 2.0 to 4.0. Therefore, these potato tubers are suitable for salads and cuttings. To make mashed potatoes they should be boiled a little bit longer than the recommended time.

Tubers of all tested varieties were found to be quite tasty – 5.5 to 8.0 points (Figure 6). At the same time, Gulliver tubers were the most delicious ones, despite the low starch content, the average score for three years was 7.5 points (according to the taste indexes: 1 – bad (unpleasant, bitter); 3 – bland; 5 – satisfactory (including sweet); 7 – good; 9 – excellent). The application of sodium selenite had no significant effect on the flesh darkening and taste quality of tubers.

Studies have shown that according to their cookery properties potatoes produced from mini-tubers obtained by the aero-hydroponic method are suitable for food consumption and further processing in food industry. Starch content in tubers was 75% or more of the potentially possible values for all tested varieties. When applying sodium selenite in average for three years, the selenium content in tubers amounted to 0.040 to 0.0375 mg/kg, which does not exceed MPC in potatoes (0.5 mg/kg). At the same time, an increase in the selenium content in tubers was obtained on average over three years when using leaf treatment with sodium selenite relative to the control of 0.08...0.10 mg/kg of raw weight (Figure 7). The data obtained provide the basis for research expansion not only to correct selenium deficiency in ecosystems, but also to increase the yield and improve the quality of agricultural production. They also confirm that the rationed application of selenium is still far from optimal, which is manifested by unstable results in a number of experiments conducted (Sychev, 2015).

Mini-tubers of a small fraction are usually rejected or undervalued, unlike mini-tubers of a standard fraction. Thus, to determine the maximum economic efficiency of their cultivation, a cost of 4.00 rubles is accepted. With a commodity yield from 14.7 to 19.7 t/ha of tubers with more than 30 mm, the cost of food potatoes was 11.72 to 15.52 rubles/kg. Therefore, when using mini-tubers of a standard fraction with the cost price up to 8.00 rub/pcs, the cost price of food potatoes would increase more than 1.5 times. Having been sold at a price of 17 rubles/kg (taken as calculated), potatoes produced from mini-tubers afforded a good profit in the range from 21.7 to 104.0 thousand rubles/ ha (depending on the variety), the profitability was 16.1 to 28.6%, respectively (Figure 8).

Mini–tubers of small fraction (less than 15 mm), as non-conforming, are rejected and are not used in the original potato seed production. Therefore, it seems promising to use such mini-tubers for growing healthy and high-quality food potatoes.

5. Conclusion

Summarizing the results of the research carried out, we come to the following conclusion:

1. The average yield of all tested varieties was at the level of 18.0 t/ha, while the share of commercial tubers in size was 96.5 to 97.4%. These indicators point out that depending on the variety it is likely to obtain more than 67 to 91% of the possible potential commercial yield, growing potatoes from mini-tubers of a small fraction;

2. Starch content in tubers of the Grand (16.5 to 18.4%) varieties was noted within the limits of potentially possible values. The highest dry matter content (23.1 to 23.5%) was found in tubers of the Grand variety, as a result, tubers can be recommended for production of processed products, for example, dry potato flakes. Potatoes grown from mini-tubers obtained by the aero-hydroponic method are suitable for cookery purposes, as well, in the food industry. Starch content in such tubers is 75% or more of the potentially possible values for all tested varieties;

3. Nitrate content in potato tubers of all varieties did not exceed the maximum permissible concentration (250 mg/kg). Consequently, tubers grown in the field from mini-tubers obtained using aero-hydroponic units with a combined nutrition system can be used for food;

4. In comparison with tubers of other varieties the raw tuber flesh of the Gulliver variety was less susceptible to browning – 7.8 to 8.3 points (in all years of research). Despite low starch content (10.8 to 14.0%), the variety received the highest rating in terms of taste (the average point was 7.5 in all years of research). Tubers of this variety seem to be suitable for vacuum treatment and freezing for long-term storage in a purified form. Consequently, potatoes grown from mini-tubers obtained by the aero-hydroponic method are appropriate for cookery purposes to be used in the food industry;

5. The obtained data provide grounds for expanding research not only to correct selenium deficiency in ecosystems, but also to increase yields and improve the quality of agricultural products;

6. Cost minimisation of mini-tuber cultivation remains an urgent task to study and develop new effective ways of obtaining original seed material, including the cultivation of food tubers for dietary purposes with tuber selenium saturation. When a commodity yield of tubers more than 30 mm in size was from 14.7 to 19.7 t/ha, the cost of food potato production amounted to 11.72 to 15.52 rubles/kg. Potatoes produced from mini seed tubers were sold at a price of 17 rubles/kg (taken as calculated).The income ranged between 21.7 and 104.0 thousand rubles/ha (depending on the variety), the profitability was 16.1 to 28.6%, respectively. Thus, it is possible to state the economic feasibility of growing food potatoes from mini-tubers of a small fraction obtained using aero-hydrophone modules with a combined nutrition system.

Data Availability Statement

All the data is available in the article.

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Edited by

• Editor:
  Takako Matsumura Tundisi

Publication Dates

• Publication in this collection
  10 July 2026
• Date of issue
  2026

History

• Received
  09 Nov 2025
• Accepted
  09 Jan 2026