An International Multidisciplinary Research Journal

Abstract

Maintaining and improving product quality in the cultivation o f agricultural crops is one o f the most pressing tasks. Due to this, the study of product quality is required in all scientific works.
The quality of the product in the stevia crop depends primarily on the chemical composition of the plant, the presence of minerals and vitamins in the plant, and their amount. In the experiment, the leaf yield of the stevia crop was 20 c / ha in the control variant without the use of mineral fertilizers. The highest rate of stevia leaf yield was recorded in the variant where 175 kg/ha of phosphorus fertilizers were applied at a high rate of 31 c / ha, with an additional yield of 11 c /ha due to mineral fertilizers.

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ISSN: 2249-7137 Vol. 10, Issue 10, October 2020 Impact Factor: SJIF 2020 = 7.13
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A.A, Khayrullaev S.Sh
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ACADEMICIA
An International
Muiltldlsciplinary Research
Journal
ACADEMICIA
An International
Multidisciplinary
Research Journal
__
South Asian Academic Research Journals.
A Publication of CIX College of Education
/ T V 1 1 1 • 1 - - n 1 О ш ъ ш ж • I T 1 \ (Affiliated to Kuruksh^ra Umwraty
(Double Blind Refereed & Peer Reviewed Jo urnal)
DOI: 10.5958/2249-7137.2020.01257.4
EFFECT OF MINERAL NUTRITION ON OVERALL LEAF AREA AND
YIELD OF STEVIA (STEVIA REBAUDIANA BERTONI)
Azizov B.M*; Ulugboev A.Y**; Kurbanov A.A***; Khayrullaev S.Sh****
*Professor,
Tashkent State agrarian University,
UZBEKISTAN
**Doctoral student,
Cotton Breeding, Seed Production and Agro-technologies Research Institute,
UZBEKISTAN
***Assistant,
Tashkent State Agrarian University,
UZBEKISTAN
****Assistant,
Tashkent State Agrarian University,
UZBEKISTAN
Email id: a.kurbonov27@mail.ru sardorxayrullayev@mail.ru
ABSTRACT
Maintaining and improving product quality in the cultivation o f agricultural crops is one of the
most pressing tasks. Due to this, the study of product quality is required in all scientific works.
The quality of the product in the stevia crop depends primarily on the chemical composition of
the plant, the presence o f minerals and vitamins in the plant and their amount. In the experiment,
the leaf yield o f the stevia crop was 20 c / ha in the control variant without the use of mineral
fertilizers. The highest rate of stevia leaf yield was recorded in the variant where 175 kg / ha o f
phosphorus fertilizers were applied at a high rate of 31 c / ha, with an additional yield of 11 c /
ha due to mineral fertilizers.
KEYW ORDS: Stevia, Medicinal Plant, Chemical Composition, Mineral Fertilizers, Calcium,
Nitrogen, Phosphorus, Potassium, Iron, Physiological Process, Yield.

ISSN: 2249-7137 Vol. 10, Issue 10, October 2020 Impact Factor: SJIF 2020 = 7.13
INTRODUCTION
Maintaining and improving product quality in the cultivation of agricultural crops is one of the
most pressing tasks. Due to this, the study of product quality is required in all scientific works.
The stevia plant is grown for its leaves, so it is advisable to study the leaf quality of stevia in
practice, as well as the factors that affect leaf quality. The quality of the product in the stevia
crop depends primarily on the chemical composition of the plant, the presence of minerals and
vitamins in the plant and their amount.
Scientific research on the product quality, yield and cultivation technology of the stevia plant has
been studied mainly in foreign countries in the research work of scientists such as P.J.Larkin,
T.A.Thorpe, J.K.Yasil, M.J.Aparajta. However, this research has been conducted in Europe and
Russia, Ukraine, Germany, Poland, Sweden, North America in the USA and Canada, and in East
Asia in countries such as Japan, China and Korea, Australia and New Zealand.
Especially in countries such as Japan, China, Korea, there is a growing interest in the stevia
plant. In Japan, stevia cultivation has risen to the level of national value.
In Uzbekistan, too, in recent years, interest in the stevia plant is growing. In this regard
I.Belolipov,T.M.Duseynov, T.K.Duseynov, J.Tursinov. It has been studied in the scientific
works of such a scientist as Baykabilov. The scientific work mainly studied the morphology,
systematics and biological properties of the plant. However, the technology of growing stevia in
the conditions of our country is not sufficiently studied, there is insufficient scientific data in this
regard.
EXPERIMENTAL METHODS
The experiment was conducted in Uychi district of Namangan region. The experimental field
consists of meadow-gray soils, moderately sandy mechanical composition, irrigated from time
immemorial, not saline. The driving layer is 0-30 and 0-40 cm, in some places there is a layer of
sand at a depth of 60-70 cm below the driving layer. Field experiments were carried out
according to BA Dospekhov's (1982) "Methods of conducting field experiments".
The second field experiment consisted of 4 variants and was conducted in four repetitions. All
returns were placed in one tier. All phenological observations and accounts were carried out in
the calculated areas of each variant, in separate plants.
Leaf level of stevia and total leaf area per hectare are determined by the method of
A.A.Nichiparovich, biological productivity is determined by the method of I.S.Shatilov,
M.K.Kayumov.
RESULTS
According to the results of many years of scientific research, the total leaf area in the field should
be at least 30-35 thousand m2 / ha for sustainable high yields from crops.
Academic A.A.Nichiporovich, along with studying the importance of the leaf in plant life,
developed the most acceptable and convenient method of determining the leaf surface. Today, in
many scientific studies, the "visechka" method, developed by a scientist, is widely used to
determine the leaf surface.

The photosynthetic activity of the cultivar depends primarily on the formation of a sufficient leaf
surface in the field. According to the results of many years of scientific research, the total leaf
area in the field should be at least 30-35 thousand m2 / ha for sustainable high yields from crops.
Data on the positive effect of mineral fertilizers on the formation of the overall leaf area o f stevia
in the experiment are given in Table 1.
TABLE 1 EFFECT OF THE NORM OF M INERAL FER TILIZER S ON COMMON
LEAF AREA OF STEVIA, THOUSAND M 2 / HA___________________
№ Options Total leaf area, thausandm2/ ha Average 3 years thousand m / ha
2017 2018 2019
1Control 25.5 24.2 22.5 24.1
2N50 P175 K50 34.1 31.9 31.3 32.4
3N50 P150 K50 31.9 30.8 30.8 30.1
4N50 K50 27.5 25.3 26.4 26.4
In the first 2017 experiment, in the control variant without the use of mineral fertilizers, the total
leaf area of the stevia plant was 25.5 thousand m2 / ha. In the fourth variant, where nitrogen and
potassium were given and phosphorus was not given, this figure was 27.5 thousand m2 / ha.
In the third variant, given the norm of 150 kg / ha of phosphorus, the total leaf area of the stevia
plant was 31.9 thousand m2 / ha. In the second variant, where phosphorus was applied at a rate of
175 kg / ha, the total leaf area of the plant was 34.1 thousand m / ha. It was observed that the
difference in the control option due to the application of phosphorus fertilizers was 4.4-6.6
thousand m2 / ha.
In the second year of the experiment, i.e. in 2018, the predominance of stevia on the leaf surface
was noted in the variants using mineral fertilizers. In all variants using mineral fertilizers, it was
found that the total leaf surface area of stevia was higher than that of the control variant.
In the control variant without mineral fertilizers, the total leaf area of stevia was 24.2 thousand
m2 / ha, in the case of application of phosphorus fertilizers at the rate of 175 kg / ha, at the rate of
31.9 thousand m2 / ha, in the case of phosphorus fertilizers at the rate of 150 kg / ha, 30.8
thousand m2/ ha, no phosphorus fertilizers, only when nitrogen and potassium fertilizers were
applied at the rate of 50 kg / ha, 25.3 thousand m2 / ha were observed.
In the experiment, it was noted that the total leaf area of stevia increased by 1.1-7.7 thousand m2
/ ha due to mineral fertilizers. In particular, it was found that phosphorus nutrition has a positive
effect on the formation of the overall leaf surface of the stevia plant.
In irrigated gray soils, it is advisable to apply mineral fertilizers in the amount of N50P150K 50 kg /
ha during the season to form a sufficient total leaf layer, which ensures the optimal course of
physiological processes in the Stevia plant.
This means that in irrigated gray soils, the Stevia plant has a high need for mineral nutrients,
including phosphorus fertilizers, throughout the growing season. The above data indicate that the
level of phosphorus supply in irrigated gray soils is low.
Stevia plant is grown for its leaves. The leaves of the stevia plant contain the substance
stivioside, which has a very high level of sweetness, and many valuable minerals.

The sweetness level o f stivioside was found to be 200 times higher than that of succharose. Due
to this, in recent years in most countries the attention to the crop of stivioside is growing.
There is also a growing interest in the stevia crop in our country, and a number of scientific
studies have been conducted in this regard.
However, scientific research on stevia cultivation under irrigated conditions is insufficient and
no clear recommendations have been made.
Due to this, the effect of mineral nutrition of stevia plant on leaf yield in irrigated gray soil
conditions was studied in the experiment. Data on the effect of mineral nutrition on the mass of a
single plant in the Stevia plant are given in Table 2.
The table below shows that the productivity of a mineral-fed stevia crop depends on the level of
adequate supply of mineral nutrients to the plant during the season.
In the experiment, it was observed that in the variants where all mineral fertilizers were applied,
the productivity of stevia was higher than in the control variant without mineral fertilizers.
TABLE 2 EFFEC T OF THE NORM OF M INERAL FER TILIZ ER S ON MASS OF PER
PLANT
№ Control Average mass of per plant Dry mass, gr/plant
overall leaf
1Control 20.3 4.3 2.5
2N50 P175 K50 31.8 7.6 5.7
3N50 P150 K 50 30.3 7.0 5.1
4N50 K50 25.5 5.2 3.4
The biological mass of one plant was 20.3-31.8 grams according to the options. The lowest value
was recorded in the 2 0 g / plant control variant, and the highest value was recorded in the variant
used at the high 175 kg / ha norms of 31.8 g / plant phosphorus fertilizers.
In the experiment, no phosphorus fertilizers were used, only nitrogen and potassium fertilizers
were used, the mass of one plant was 25.5 g / plant, the difference compared to the control option
was 5.2 g / plant. In the experiment, an increase in the mass of one plant by 5.2 -10.5 grams was
observed due to mineral nutrition.
In practice, the study of the biological mass of a plant, as well as the mass of a plant, is of great
scientific and practical importance. In this regard, the positive effect of agro-technical measures,
including mineral nutrition, on the formation of dry mass of stevia was studied in the experiment.
In the experiment, the dry biological mass of one plant in stevia was 4.3-7.6 grams according to
the options. The lowest value by dry mass was observed in the control variant without the use of
4.3 g / plant mineral fertilizers. The highest value was observed under the conditions of
application of 7.6 g / kg of plant mineral fertilizers N50 P175 K 50 kg / ha.
Dry leaf mass on options consisted of 2.5-5.7 g / plant. The lowest value was recorded in the 2.5
g / plant control option, only 3.4 g / plant under conditions where nitrogen and potassium
fertilizers were used in the N50K50 norm. Under the conditions of application of mineral
fertilizers N50P150K 50 norm, the dry leaf mass was 5.1 g / plant. A relatively high rate of dry leaf

mass was observed under the conditions of normal application of 5.7 g / plant mineral fertilizers
N50P175 K50 kg / ha.
Therefore, in order to increase the productivity of the stevia plant under irrigated conditions, it is
recommended to fully meet the plant’s need for mineral nutrients, including phosphorus
fertilizers, during the season. Experiments have shown that incomplete satisfaction of the plant's
need for phosphorus nutrients has a negative effect on the level of stevia accumulation.
Yield is one of the most important indicators in the cultivation of agricultural crops. Productivity
is the expected result, the final product. In any scientific work, the main focus is on improving
product quality and increasing productivity.
The main consumable product in the stevia crop is the leaf of this plant, i.e. stivioside, a
substance that replaces succharose from the stevia leaf. Stevioside is distinguished from
succharose by its high sweetness level, low calorie content and easy digestion.
Due to the low potency of stevioside, the human body is not adversely affected. It is
recommended to consume stivioside products, especially for patients with sugary diabetes.
Because despite of the very high level of sweetness of stevia, it does not pose a risk to people
with diabetes.
However, because the sweetness equivalent is so high, many foreign countries are gradually
switching to stivia cultivation.
Stevia products are widely consumed, especially in Southeast Asian countries. In countries such
as China, Japan, South Korea, and Vietnam, more than 50% of sugar consumption is found in
stevia products.
In recent years, in most developed countries in all regions of the world, there is a growing
interest in this crop and the need for its products.
However, in our country there is not enough experience in the cultivation of stevia, the laws of
formation of the general leaf layer in this crop, the course of the process of photosynthesis are
not sufficiently studied.
In the experiment, the positive effect of mineral nutrition on the leaf yield of Stevia plant in
irrigated gray soil conditions was studied. The results of the experiments obtained are presented
in Table 3.
TABLE 3 EFFEC T OF M INERAL NUTRITION ON STEVIA LEAF YIELD
№ Options Leaf yield Additional yield,
c / haKg / m2 c / ha
1Control 0.20 20 -
2N50 P175 K50 0.31 31 11
3N50 P150 K50 0.30 30 10
4N50 K50 0.25 25 5
In the experiment, mineral nutrition showed a positive effect of stevia plant on leaf yield. In all
variants using mineral fertilizers, stevia leaf yields were found to be higher than in the control
variant without mineral fertilizers.

In the experiment, the leaf yield of the stevia crop was 20 c / ha in the control variant without the
use of mineral fertilizers. The highest rate of stevia leaf yield was recorded in the variant where
175 kg / ha of phosphorus fertilizers were applied at a high rate of 31 c / ha, with an additional
yield of 11 c / ha due to mineral fertilizers.
When phosphorus fertilizers were applied at the rate of 150 kg / ha, the yield of stevia was 30 c /
ha, and 10 c / ha was grown due to mineral nutrition.
Phosphorus fertilizers were not used, only small amounts of nitrogen and potassium fertilizers
were used, the yield of stevia was 25 c / ha, and only 5 c / ha of additional crops were grown due
to mineral fertilizers.
The most important indicator in the cultivation of agricultural crops is productivity, and the
reliability of the data obtained on yield depends on the correct performance of the experiment.
The reliability of the data will be at such a high level that productivity data will be detected
across all iterations.
In the experiment, the effect of mineral nutrition on the yield of Stevia was studied in the
calculated areas of experiment field in all variants and repetitions according to the standard
requirements. Plant productivity records were kept in accordance with the adopted methodology.
Data on the positive effect of mineral nutrition on the overall leaf yield of Stevia plant on the
repetitions in the experiment are given in Table 4.
TABLE 4 STEVIA YIELDS BY REPETITIO NS
№ Options Yield by repetitions, c / ha Average yield, c / ha
I II III IV
1Control 19.6 22.1 21.5 18.9 20.5
2N50 P175K50 30.5 32.2 31.7 29.8 31.0
3N50P150K50 29.2 31.5 31.0 28.6 30.1
4N50 K50 24.3 26.9 26.4 23.7 25.3
Experimental results showed that mineral nutrition had a significant effect on Stevia
productivity. In all repetitions, the lowest yields were recorded in the control variant without the
use of mineral fertilizers.
In the control variant, Stevia's yield on repetitions was 18.9 from 22.1 c / ha. The difference in
recurrences of stevia on leaf yield was 0.7-2.2 c / ha. In the control variant, the average leaf yield
of Stevia was 20.5 c / ha. In all studied variants, stevia yields were higher than in the control
variant.
Of the mineral fertilizers used only nitrogen and potassium fertilizers, in the absence of
phosphorus fertilizers, the average yield of stevia was 25.3 c / ha, the difference compared to the
control option was 4.8 c / ha. Under the conditions of normal application of mineral fertilizers
N50P150 K50, the yield of stevia was 30.1 c / ha.
In the experiment, relatively high yields of stevia were observed in the second variant of mineral
fertilizers N50P175K50 norm applied to 29.8-32.2 c / ha. In this variant, the average yield of Stevia
was 31.0 c / ha.

Under conditions of normal application of mineral fertilizers N 50P150K50, the leaf yield of stevia
was 28.6-31.5 c / ha, the average yield was 30.1 c / ha. Stevia plant needs phosphorus fertilizers
throughout the growing season.
The results of the experiments showed that the yield of stevia depends on the adequate supply of
phosphorus fertilizers to the plant during the growing season.
Therefore, it is recommended to use mineral fertilizers, including phosphorus fertilizers, at a
relatively high N50P175K50 rate to grow high leaf yields from the stevia plant under irrigated
conditions.
CONCLUSION
1. Soil moisture is a necessary condition for seed germination in the conditions of introduction.
This feature is related to the origin of the species, i.e. high air humidity (75-80%) and air
temperature (25-35 C).
2. It was found that the germination of plant seeds at high temperatures (28°C) under laboratory
conditions and in moist sand under the film is 24-8%.
3. In introduction conditions, soil moisture is a necessary factor for plant growth from seed. In
the natural habitat, the influence of air temperature and humidity is also important in the origin
of the species.
4. The short day tropical S.rebaudiana introduced in Namangan region has fully passed all stages
of ontogeny. Air temperature affects the onset times of vegetation. The onset of budding and
flowering depends on the reduction of daylight.
5. S.rebaudiana plant can produce leaf biomass from 3.5-4 tons per hectare, which is a source of
high quality raw materials for various sectors of the economy.
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