Effect of some foliar fertilizers on the growth, development and yield of dt51 soybean in winter season, 2020 gia lam, ha noi

VIETNAM NATIONAL UNIVERSITY OF AGRICULTURE

FACULTY OF AGRONOMY

UNDERGRADUATE THESIS
TITLE:
EFFECT OF SOME FOLIAR FERTILIZERS ON THE
GROWTH, DEVELOPMENT AND YIELD OF DT51
SOYBEAN IN WINTER SEASON,
2020 GIA LAM, HA NOI
Student

:

LE LINH CHI

Student code

:

611757

Class

:

K61KHCTT

Supervisor

:

PhD. NUYEN VAN PHU

Department

:

PLANT PHYSIOLOGY

HANOI-2021


DECLARATION

I declare that the undergraduate thesis is the result of my research. The
data and results mentioned in this thesis are honest and not used in any
published thesis, dissertations, and scientific research projects previously.
I hereby commit that the information cited in the thesis ensuring cited as
prescribed. I bear full responsibility for these reassurances.
Hanoi, February 24, 2021
Student

Le Linh Chi

i


ACKNOWLEDGEMENT

After a long period of studying in the university, the undergraduate thesis

is the most important time for me to improve and have more knowledge to
research the reality with teachers and staff in the Faculty of Agronomy,
especially teachers in the Plant Physiology Department. During the internship
and undergraduate thesis, not only my efforts but also I received a lot of help
from teachers, family and friends.
First of all, I would like to express my deep gratitude to PhD. Nguyen
Van Phu who dedicated guidance and helped me during the study process and
complete thesis
Specially thanks to the Dean Of Faculty and all the teachers in the Faculty
of Agronomy, especially the teachers in Plant Physiology who helped me
complete this undergraduate thesis.
I would also like to thank the staff of the Department of Plant Physiology
for helping, sharing valuable experiences as well as creating the best conditions
for me to do this undergraduate thesis.
Finally, I would like to thank my family and friends who are always there
to care for and encourage me throughout the undergraduate thesis process.
Sincerely!
Hanoi, February 24, 2021
Student

Le Linh Chi

ii


ABSTRACT
Research on the effects of some foliar fertilizers on the growth,
development and yield of soybeans in winter season 2020, Gia Lam, Ha Noi.
Since then, contributing to the selection, creation and construction of cultivation
methods to determine the most effective foliar fertilizers for high yield and high

quality soybean of varieties soybean in Vietnam.
The pot experiment was carried from September 2020 to January 2021 at
the Faculty of Agronomy, Vietnam National University of Agriculture, Trau
Quy commune, Gia Lam district, Hanoi. The experiment was arranged is
arranged in the randomized complete block (RCB) repeat time times. Five
treatments included T1 (H2O), T2 (Dau Trau 501), T3 (Grow More 30-1010+TE), T4 (Profarm- n29) and T5 (Seaweed 95%). Monitoring criterias:
height, number of leaves, number of flowers, leaf area, leaf area index... Using
Excel software and IRISSTAT 5.0 biological statistical software to process data
The results showed that foliar fertilizer has good effects on criterias of
growth and development of DT51 soybean in which T5: Seaweed 95% helped
the plant to grow best, reached the highest of yield 19.64 quintals/ha and got the
highest net profit 91.75 million VND/ha. Meanwhile, no significant difference
in the growth, development and yield among foliar fertilizers.

iii


CONTENTS

DECLARATION ................................................................................................... i
ACKNOWLEDGEMENT .................................................................................... ii
ABSTRACT ......................................................................................................... iii
CONTENTS ......................................................................................................... iv
LIST OF ABBREVIATIONS ............................................................................. vii
LIST OF TABLES ............................................................................................. viii
LIST OF FIGURES .............................................................................................. ix
PART 1. INTRODUCTION ................................................................................. 1
1.1. Introduction section ........................................................................................ 1
1.2. Research objective and requirement .............................................................. 2
1.2.1. Objective ..................................................................................................... 2

1.2.2. Requirement ............................................................................................... 3
PART 2. LITERATURE REVIEW ...................................................................... 4
2.1. Valuations of soybean .................................................................................... 4
2.1.1 Economic value of soybean ......................................................................... 4
2.1.2 Agricultural value of soybean ...................................................................... 5
2.2. Soybean production in the world and Vietnam.............................................. 5
2.2.2 Soybean production in Vietnam ................................................................... 7
2.3. Function and requirement of some basic mineral nutrients elements for
soybean ...................................................................................................... 9
2.3.1. Role of Nitrogen .......................................................................................... 9
2.3.2. Role of Phosphorus ................................................................................... 10
2.3.3. Role of Potassium...................................................................................... 10
2.3.4. Role of Magnesium ................................................................................... 11
2.3.5. Role of Iron ............................................................................................... 11

iv


2.3.6. Role of Manganese .................................................................................... 11
2.3.7. Role of Copper .......................................................................................... 12
2.3.8. Role of Bo ................................................................................................. 12
2.4. Mechanic of uptake foliar nutrition and advantages, disadvantages of
foliar application ..................................................................................... 12
2.4.1. Mechanic of uptake foliar nutrition .......................................................... 12
2.4.2. Advantages and disadvantages of foliar application ................................. 14
2.5. Research of foliar application for crops, soybean in the world and
Vietnam ................................................................................................... 15
2.5.1. Some results of foliar application in the world ......................................... 15
2.5.2. Some results of foliar application in Vietnam .......................................... 17
PART 3. RESEARCH CONTENT AND METHOD ......................................... 20

3.1. Materials of research .................................................................................... 20
3.2. Location and time research .......................................................................... 21
3.3. Research content .......................................................................................... 21
3.4. Method of research ....................................................................................... 21
3.4.1. Experimental design .................................................................................. 21
3.4.2. Map of experiment .................................................................................... 22
3.4.3. Cultivation techniques ............................................................................... 22
3.5. Tracking and method criteria ....................................................................... 23
3.5.1. Growth criteria .......................................................................................... 23
3.5.2. Physiological criteria ................................................................................. 23
3.5.3. Yield criteria .............................................................................................. 24
3.5.4 Processing data. .......................................................................................... 25
PART 4. RESULTS AND DISCUSSION .......................................................... 26
4.1. Effect of foliar fertilizers on plant height of DT51 soybean ........................ 26
4.2. Effect of foliar fertilizers on number of leaves of DT51 soybean ............... 29
4.3. Effect of foliar fertilizers on branching ability of DT51 soybean ............... 31

v


4.4. Effect of foliar fertilizers on leaf area and leaf area index of DT51
soybean .................................................................................................... 33
4.5. Effect of foliar fertilizers on nodule formation of DT51 soybean ............... 35
4.6. Effect of foliar fertilizers on dry matter of DT51 soybean................................ 37
4.7. Effect of foliar fertilizers on flower formation of DT51 soybean ............... 39
4.8. Effect of foliar fertilizers on SPAD index of DT51 soybean....................... 41
4.9. Effects of foliar fertilizers on yield components of DT51 soybean ............. 42
4.10. Effect of foliar fertilizers on yield of DT51 soybean ................................. 45
4.11. Economic efficiency when using foliar fertilizer for DT51soybean in
Gia Lam-Hanoi, winter season 2020 ...................................................... 47

PART 5: CONCLUSION AND RECOMMENDATION .................................. 49
5.1 Conclusion ..................................................................................................... 49
5.2 Recommendation ........................................................................................... 49
PART 6: REFERENCE...................................................................................... 50
APPENDIX 1: ECONOMIC ACCOUNTING ................................................... 52
APPENDIX 2: SOME PICTURES OF THE RESEARCH ................................ 55
APPENDIX 3: RESULTS OF DATA PROCESSING WITH IRRISTAT
SOFTWARE ........................................................................................... 59

vi


LIST OF ABBREVIATIONS

Acronyms

English meaning

CV%

Coefficient of variation

DAS

Day after sowing

Et al

And others

FAO

The Food and Agriculture Organization

IRRISTAT

Agricultural statistical software

LA

Leaf area

LAI

Leaf area index

LSD

Least significant different

No.

Number

RCB

The randomized complete block

T

Treatment

vii


LIST OF TABLES

Table 2.2.1a Soybean production in the world 2010-2019 ................................... 6
Table 2.2.1b Soybean production of some countries 2017 - 2019........................ 7
Table 2.2.2. Soy bean production in Vietnam from 2009–2019........................... 8
Table 4. 1 Effects of foliar fertilizers on plant height of DT51 soybean ............ 27
Table 4. 2 Effects of foliar fertilizers on number of leaves of DT51 soybean ... 29
Table 4.3 Effect of foliar fertilizers on branching ability of DT51 soybean ...... 31
Table 4.4 Effects of foliar fertilizers on leaf area and soybean leaf area index
of DT51 soybean ..................................................................................... 33
Table 4.5 Effect of foliar fertilizers on nodule formation of DT51 soybean ...... 36
Table 4.6 Effect of foliar fertilizers on dry matter of DT51 soybean ................. 38
Table 4.7 Effect of foliar fertilizers on number of flowers and flowering
time of DT51 soybean ............................................................................. 40
Table 4.8 Effect of foliar fertilizers on SPAD index of DT51 soybean ............. 41
Table 4. 9 Effects of foliar fertilizers on yield constituent factors of DT51
soybean .................................................................................................... 42
Table 4.10 Effect of foliar fertilizers on yield of DT51 soybean........................ 45
Table 4.11 Economic efficiency when using foliar fertilizer for
DT51soybean .......................................................................................... 47

viii


LIST OF FIGURES

Figure 4.1. Growing dynamic of plant height of DT51 soybean ........................ 28
Figure 4.2. Growing dynamic of leaf number of DT51 soybean ........................ 30
Figure 4.3. Growing dynamic of number of branches ........................................ 32
Figure 4.10 Effect of foliar fertilizers on theoretical yield and actual yield of
DT51 soybean ......................................................................................... 46

ix


PART 1. INTRODUCTION

1.1. Introduction section
The soybean or soya bean (Glycine max) is a species of legume (Fabaceae),
a native species to East Asia. As one of the four important crops ( corn, rice,
wheat, soybean) provides 43% of the nutritional energy and 40% of protein so
soybeans are used for many purposes, food for human and cattle which is used
largely as a supplement to cereal seeds in feed domesticated livestock such as
dairy cows, cattle, pigs, goats, sheep, horses and poultry. For agricultural
production, soybean is a significant crop in the farming system, crop rotation
and soil improvement (Duong Hong Dat, 2012).
In terms of food value, soybean seeds have a high nutritional ingredient.
Nguyen Thi Hien and Vu Thi Thu (2004) said that the average protein content of
soybeans ranges from 35.5 to 40 %. Besides, soybean seeds also contain lipids
15-20%, carbohydrates15-16% and many vitamins such as Vitamins B1, B2, C,
D, E, K and minerals important for life. (Quotes from Tran Van Dien, 2007).
Protein in soybean is good quality and can completely replace animal oil in
human die that is used in medicine to help avoid malnutrition among children in
poor countries and helps to limit goiter.
In recent times, the demand for soybeans domestically as well as for export

has been increasing, while natural disasters occur frequently and agricultural
land is shrinking. In order to increase soybean yield, people use new varieties
with high yield, suitable planting season, reasonable fertilizers, watering in
which special attention is paid to fertilizers techniques for soybean plants. In
addition to traditional fertilizers, foliar fertilizers for soybean have been applied
in recent years (Vu Quang Sang et al, 2015). Currently, in the market, there are
many types of nutritional preparations for leaves, but their effect on plants as
well as the most effective fertilizers technique for the user needs to be studied.

1


Foliar fertilizers overcome nutritional deficiencies, prevent nutrient
deficiencies due to limited absorption of the root system and limited internal
transport within the plant, replace or supplement the root-based fertilizers
method, increase resistance to pests and diseases, increase resistance to cold.
Moreover, foliar fertilizers help to protect the environment, overcoming the
pollution problem caused by fertilizing the soil.
DT51 soybean variety was selected by Legumes Research and Development
Center- Field Crops Research Institute from the hybrid combination between
LS17xDT2001. According to the assessment, DT51 has outstanding advantages:
high yield can be planted 3 farming seasons/year, the rate of 3-seeds reaches
over 30%.

In Vietnam, DT51 soybean variety is planting to develop a

concentrated soybean-producing region towards commodity to meet market
demand with the conventional fertilizing process, not using foliar fertilizer.
There have not really been many studies on the effect of foliar fertilizer on the
growth of this soybean variety.

Therefore, in order to contribute quickly to the use of foliar fertilizer and to
find the best foliar fertilizer to be put into production, on that basis, we studied
the topic: “Effect of some foliar fertilizers on the growth, development and
yield of DT51 soybean variety in the winter season, 2020 Gia Lam, Ha Noi”.
1.2. Research objective and requirement
1.2.1. Objective
Research the effects of some foliar fertilizers on the growth, development
and yield of soybean that is grown in the winter season 2020, Gia Lam, Ha Noi,
determinate the most effective foliar fertilizers for high yield and high quality of
soybean.

2


1.2.2. Requirement
- Evaluate the effect of foliar fertilizer on some growth indicators of DT51
soybean
- Evaluate some physiological indicators of DT51 soybean when using
foliar fertilizer.
- Evaluate DT51 soybean’s some yield components are affected by some
foliar fertilizer
- Evaluate the economic efficiency when using foliar fertilizers

3


PART 2. LITERATURE REVIEW

2.1. Valuations of soybean
2.1.1 Economic value of soybean

The economic value of soybean mainly depends on the nutritional content
of soybean seeds. Essential nutritional ingredients that can replace products
from animals, soybean seeds are used a lot in the food processor for humans
such as tofu, soy milk, vegetarian food, ice cream, confectionery, etc. In
industry, soybean oil accounts for about 50% of total vegetable oil. From
soybean oil, people can produce hundreds of other products: paint, candles,
soap, ink, plastics, artificial rubber.
In the 1970s of the XX century in Brazil, black soybean have produced
the highest profit on a unit of agricultural land area for farmers that compared to
other seed crops (Duong Hong Dat, 2012)
In terms of medicine, soybean has a very important significance, the use
of soybeans helps to cure several diseases: cardiovascular disease, anti-cancer,
aging prevention and osteoporosis of old age. Soybean enhances immune
function due to its high content of vegetable protein which has been referred to
as "plant meat". Using beans not only adds protein to the body but also avoids
the increase in cholesterol. Soybeans contain a large amount of lecithin,
isoflavones, which play a big role in improving the mind, whitening teeth,
skincare and preventing cancer.
There are two types of isoflavones in soybeans, daidzein and genistein
which have a chemical structure as the female hormone estrogen, also known as
a phytoestrogen. Phytoestrogens have similar effects to natural estrogens but
weaker and soybeans consist of four chemical structures, aglycones, daidzein,
genistein and glycitein. Many studies show that soybeans contain isoflavones
and are considered a food to increase femininity and protect women from many

4


diseases, so soybeans are also known as the "miracle" of women. Many clinical
studies in humans and animals are being studied precisely answering these

precious effects.
2.1.2 Agricultural value of soybean
According to research, the soybean plant is an important crop in the
Vietnamese cropping system, being intercropped, pillow growing and increasing
crops in agriculture (Tran Van Lai, 1999). Soybeans, like all other legumes, play
a very important role in soil improvement because they can accumulate free
nitrogen in the air for self-use and enrich the soil nitrogen through the symbiosis
of Rhizobium Japonicum in the root system. Under favorable conditions, these
Rhizobium can synthesize a nitrogenous amount equivalent to 20-25 kg/ha
(Pham Van Thieu, 2009). In the crop rotation system, if the arrangement of
crops is appropriate with soybean plants, it will reduce the fertilizer costs
significantly. Soybean’s leaf and stem are also used as green manure and replace
organic fertilizer because the N content is about 0.05% in stem and in leaves
accounts for about 0.19% (Nguyen Danh Dong, 1982).
Soybeans are an important source of food in livestock, especially bred
cattle. The soybean plant can be used either as direct food or dried mashed as a
complete feed. Industrial by-products such as soybean meal which contain quite
high nutritional components are used a lot in livestock production.
2.2. Soybean production in the world and Vietnam.
2.2.1 Soybean production in the world
According to the Food and Agriculture Organization of the United
Nations (FAO), soybean production in recent years in the world has been
increasingly expanded and developed.
In 2019, the USA was the country with the largest soybean production in
the world (120.51 million tons), quite different from 104.54 million tons
compared to the fourth-ranked country, China (15.97 million tons). Soybean is

5

the 2nd largest crop in the USA after corn and valid annual is about 4 billion
dollars. (According:Statista.com)
Currently, in the world, there are about 98 soybean-growing countries.
With a high nutritional value and can be processed into many different products
for human consumption and animal feed. Soybean production has been
continuously increased over the years.
Table 2.2.1a Soybean production in the world 2010-2019
Year

Area (million ha)

Yield (ton/ha)

Quantity (million ton)

2010
2011
2012
2013
2014
2015
2016
2017
2018
2019

102.77
103.76
105.37
111.11

117.73
123.9
122
125.85
124.02
124.5

2.58
2.52
2.29
2.49
2.6
2.67
2.73
2.86
2.78
2.77

265.09
261.6
241.34
277.67
306.3
323.31
335.9
359.53
344.64
333.67

Source: FAO Statistic Database (2020)

The worldwide soybean’s area in 2019 was 124.5 million hectares, an
increase of 21.73 million hectares compared to 2010. Along with the increase in
area and yield, the total soybean quantity of the world in 2019 also increased by
68.58 million tons compared to 2010. In general, the annual soybean area in the
world increased by an average of around 1 million hectares.

6


Table 2.2.1b Soybean production of some countries 2017 - 2019
Year

Area (million ha)

Yield (ton/ha)

Quantity (million ton)

Country

2017

2018

2019

2017

World
Argentina

Brazil
China
USA

125.85
17.33
33.96
8.24
36.24

124.02
16.32
34.78
8.42
35.45

120.05
16.58
35.88
8.43
30.35

2.86 2.78 2.77 359.53 344.64 333.67
3.17 2.31 3.33 54.97 37.79 55.26
3.38 3.39 3.18 114.73 117.91 114.27
1.85 1.9
1.87 15.29 15.97 15.73
3.31 3.4
3.19 120.06 120.51 96.79
Source: FAO Statistic Database (2020)

No.
1
2
3
4
5

2018 2019 2017

2018

2019

Currently, the top 4 soybean-growing countries in the world are the USA,
Brazil, Argentina and China (Table 2.2.1b). These countries account for about
76% of the world's soybean area and about 84.53% of the world's soybean
quantity. In 2019, the three countries America, Brazil and Argentina have
soybean yield that was higher than the world, the USA’s soybean yield was
3.4(tons/ha) higher than the world, Brazil was 3.39 (tons/ha) and Argentina was
3.33 (tons/ha). The strong growth of soybeans in these countries was the result
of adopting techniques, mechanization in agricultural production, high-yielding
transgenic varieties and pest resistance.
2.2.2 Soybean production in Vietnam
In Vietnam, soybean is the type of old crop, suitable for many different
climate zones. Until now, soybean has become an important crop in the
agricultural system of the country, but soybean production area tends to decline.
Soybean has imported to Vietnam increased in recent years. In March
2020, soybean imported to Vietnam reached 211.3 thousand tons, worth 85.8
million USD, up 63.1% in quantity and 59.9% in value over to the previous

month, an increase of 88.2% in quality and 89.4% in value compared to March
2019. Generally in the first quarter of 2020, soybean’s import quality reached

7


430 thousand tons, worth 176.4 million USD, risen 2.1% in quality and 5.6% in
value over the same period in 2019.
According to the Food and Agriculture Organization of the United
Nations (FAO), soybean production in recent years in Vietnam has fluctuated as
shown in the table below
Table 2.2.2. Soy bean production in Vietnam from 2009–2019
Year
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019

Area (thousand ha)
147.
197.8
181.39
119.61

117.19
109.35
100.61
995.78
679.93
533.64
496.61

Yield (ton/ha)
Quantity ( million ton)
1.46
215.2
1.51
298.6
1.47
266.53
1.52
173.67
1.44
168.29
1.43
156.55
1.45
146.34
1.61
160.7
1.5
101.86
1.52
813.48

1.53
760.01
Source: FAO Statistic Database (2020)

Through the above statistics table, we can see that the area, yield and
quality of soybean in Vietnam fluctuate unevenly over the years. From 2009 to
2019, the soybean area tended to decrease overall, but from 2013 to 2015, the
area planted was gradually increasing. Soybean’s yield has been stable over the
years and is gradually increasing, with the highest yield of 1.61 tons/ha in 2016.
Quality increased sharply from 2017-2018 up to 711.62 thousand tons but then
decreased (53.47 million tons) in 2019.
With the local market advantage of reducing transport and circulation
costs, the good quality of fresh seeds, suitable for human food, Vietnam’s
soybeans will be able to compete with imported soybeans, competing with other
crops: rice and maize

8


Soybean is widely grown throughout Vietnam but still has some
limitations and has not fitted the domestic market demand due to many reasons
such as lack of good seeds, lack of investment in fertilizers and materials, small
scale. It is forecasted that in the coming years, Vietnam will have a shortage of
about 4-6 million tons of soybeans with 2-3 billion USD, exceeding the current
rice export and becoming a country of soybean importer.
Currently, Vietnam is in a strategy to develop 350-700 thousand hectares
of soybean production with a yield of 20 quintals/hectare to increase production
efficiency, increase competitiveness, reduce imports, and strive to reach 0.7
million tons soybeans/year, self-sufficient 20-30% of annual consumption, soil
improvement, environmental protection. It can be seen that soybean is a crop

with great output, bringing economic efficiency to farmers as well as improving
the efficiency of land use and soil improvement in the current period.
2.3. Function and requirement of some basic mineral nutrients elements for
soybean
2.3.1. Role of Nitrogen
- Nitrogen is present in many important organic compounds that play a
decisive role in metabolism and energy as well as physiological activities of the
plant.
- N is involved in the structure of Protein - is an important structural
component of protoplasts and enzymes.
- N participates in the structure of nucleic acid - the nucleus of the cell,
which determines the genetic nature of the plant.
- N is also a component of chlorophyll, synthesizing organic compounds
of the plant body.
- N is a component of important vitamins such as B1, B2, B6...

9


With these important roles above, N determines the whole life and yield
of plants. However, N also has two faces on plants. If the excess or lack of N are
harmful to plants.
2.3.2. Role of Phosphorus
-A component of the protoplasm and nucleus, has a direct influence on the
process of cell division, affects the growth and growth of plants. Young organs
with a strong meristem are always in high demand for P.
- As a subdivision of the protoplasm, it affects the permeability of the
cells, affects the ability to absorb nutrients as well as the plant's resistance to
resistance. P increases cold tolerance in plants, promotes the development of the
root system and meristem tissue.

- Participating in building ADP, ATP are compounds rich in cell
bioenergy, affecting biological processes of plants such as respiration,
photosynthesis, water absorption and mineral salts ...
2.3.3. Role of Potassium
- Has a great influence on the exchange of carbohydrates. K promotes the
exchange, transport and metabolism of carbohydrates in the plant, thus helping
the plant to harden, clear, and limit falling.
- K profoundly affects the protoplasmic state, K increases the hydration of
the protoplasm of cells, reduces viscosity, increases the ability of cells to retain
water. Therefore, K increases the cold tolerance and disease resistance of the
plant.
- Promote the synthesis of vitamins.
- Promote respiration and affect the activity of enzymes: amylase,
saccharase ... promoting the synthesis of sugar and ripening process of plants.
- Potassium also promotes the iron absorption of plants.

10


2.3.4. Role of Magnesium
- Magnesium is an important component of the chlorophyll molecule, so it
determines the photosynthetic activity of the plant. This is also the activator of
many enzymes that are important for the respiration and metabolism of the
plant. Mg is essential for short-term crops such as rice, corn, beans, potatoes...
Mg will increase the starch content in the product.
- Magnesium plant in the form of Mg2+. Magie ions in plants are
concentrated in young parts.
- Mg deficiency slows flowering, plants often have yellow leaves due to
lack of chlorophyll. The typical symptom is that the veins are green while the
pulp has turned yellow. The appearance of necrotic tissue is usually from the

lower leaves, mature leaves to young leaves, because Mg is a flexible element,
plants can be reused from older leaves.
2.3.5. Role of Iron
- The most important role of iron is activating enzymes of photosynthesis
and respiration. It does not participate in chlorophyll composition but has a
decisive effect on chlorophyll synthesis in plants. The iron content of leaves is
closely related to the chlorophyll content in them.
- Fe deficiency usually occurs on soils with limestone, phosphorus, lime
fertilizers and high pH. The iron-deficient leaves will change from green to
yellow or white in the flesh, while the veins will remain green. Iron deficiency
symptoms appear first on young leaves, then to old leaves, because Fe does not
move from old leaves to young leaves.
2.3.6. Role of Manganese
- Mg is an active element of many enzymes of photosynthesis, respiration
and molecular nitrogen fixation.
- Typical symptoms when plants are deficient in Mn are leaf veins and
vasculature turning yellow, all leaves are light green, then yellow spots appear

11


on leaf flesh and develop necrotic spots on leaves. If insufficient, leaves will be
dry and dead. Mn deficiency symptoms can manifest in old or young leaves
depending on the plant
2.3.7. Role of Copper
- Cu is an active element of many enzymes of protein synthesis, nucleic
acid and nitrogen nutrition of plants.
- The phenomenon of lack of fields usually occurs in swampy lands,
swampy fields. Plants lacking copper often have gums phenomenon (very
common in fruit plants), accompanied by necrotic lesions on leaves or fruit.

With herbaceous plants, if there is a lack of copper, it will lose the green color of
the leaf tip.
2.3.8. Role of Bo
- Bo is one of the most effective trace elements in plants. B has a direct
impact on cell differentiation, hormone metabolism, N exchange, water and
other minerals, the most obvious effect of B is on meristem at the apical growth
and flower differentiation, pollination, fertilizers, fruit formation.
- When B is deficient, shoots and growth peaks die, lateral buds decrease
gradually, flowers do not form, fructification rate is poor, fruit falls easily, roots
grow poorly, leaves are thickened. Symptoms of B deficiency often manifest in
the anterior immature parts.
2.4. Mechanic of uptake foliar nutrition and advantages, disadvantages of
foliar application
2.4.1. Mechanic of uptake foliar nutrition
Normally, the leaves are responsible for photosynthesis, CO 2, O2 and
dissolved minerals are easily assimilated in the form of ions from solution
through stomata. However, this uptake is highly dependent on the cutin layer of
the leaves. The cuticle layer can be thick and thin depending on the type of plant
and the age of the plant. Minerals can completely penetrate through microscopic

12


pores in the cutin layer, cell wall and membrane system. The diameter of these
holes is larger than 1mm and the density is very high 10 10 holes/dm2 of leave
(Horst, M. 1996). With such a small-diameter, solutes can easily pass but larger
molecules such as organic molecules, chelates are difficult to pass.
Temperature and weather conditions also affect the efficiency of foliar
nutrition, when using foliar nutrition, people often incorporate the spray leaf
surfactants at cool and it’s not (Nguyen Van Phu, 2002). The process of nutrient

uptake by leaf cells is essentially passive, the rate of absorption depends much
on the physiological status of the leaves and plant nutrition.
The process of nutrient uptake through leaf cells, like the uptake of
nutrients through the roots. It is the transport of minerals across the biological
layer, which is a mode of active transport. Absorption of nutrients through
leaves is rapidly effective under nutrient-poor soil conditions and the uptake of
nutrients through the roots is limited. This is considered as a supporting method
to supplement nutrients in periods of nutritional imbalance when plants switch
from nutritional growth to real growth with macronutrients. Because minerals
are heavily concentrated in the formation of reproductive organs, root growth is
greatly reduced that impaired absorption of minerals. Therefore, the supplement
by foliar spray method will overcome the nutritional imbalance of the plant at
that stage, helping the plant to grow and develop better (Nguyen Van Phu,
2002). According to Horst, M (1996), the foliar absorption of mineral ions is
stronger than the anion
On the surface of the leaves are stomata, nutrients dissolve into cells
through stomata. Stomata is a microscopic hole in the surface of the leaf,
helping the plant evapotranspiration to stabilize the plant's temperature, opening
for CO2 to participate in photosynthesis.
Some ions also penetrate directly through the leaf epidermis, this path
depends on the structure of the leaves, cutin layer,...

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Nutrition penetrates vacuoles, vacuole is considered as the repository of
nutrients before being absorbed into cells.
The absorption of ions at night is usually more active and intense when
the stomata are open. Older leaves absorb less than young leaves. When the
concentration of the off-leaf solution is too high, the uptake of nutrients is also

limited.
The process of absorption of nutrients through the roots is mainly, foliar
fertilizers cannot replace the original fertilizers.
2.4.2. Advantages and disadvantages of foliar application
a. Advantages of foliar application
According to Tluto et al. (1999), Nguyen Van Phu (2003), the foliar
fertilizers method is particularly effective in the following cases:
- The soil layer is poor in nutrition and drought, making the root's ability
to absorb nutrients limited.
- Foliar nutrition is particularly effective and popular with elements such
as Mg, S and especially trace elements.
- Foliar nutrition has a high utilization rate of 95% compared to only 4050% of nutrients in the soil, thus saving fertilizer and reducing soil pollution.
- Adjust the imbalance of plants when plants switch from nutritional
growth to real growth. At this time, the growth of the root system is greatly
reduced, causing impaired mineral absorption. Therefore, the supplement by
foliar spray method will overcome the nutritional imbalance of the plant at that
stage.
- Foliar nutrition is very effective when the soil has an ionic antagonism
phenomenon. According to Vu Quang Sang et al (2015), in conditions of soil
rich K+ greater than 300mg/kg of soil and Mg2+ greater than 160 mg/kg of soil,
the absorption of Mg2+ will be prevented due to the phenomenon of plant ion
antagonism with lack of Mg2+, applying Mg2+ to the soil will cause the plant to

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lose nutritional balance and die due to Mg2+ poisoning. Meanwhile, fertilizing
with Mg2+ through leaves helps plants grow well. The plants are fertilized
through the leaves grow stably, have fewer pests and diseases and resistant to
unfavorable conditions such as inundation, drought, salinity.

- Apply foliar fertilizers to increase product quality such as increasing
sugar content in sugarcane, increasing fruiting, firm seeds, early ripening, good
appearance, increasing commercial value, increasing content of trace elements.
b. Disadvantages of foliar application
The method of foliar fertilizers is highly effective but still needs to
overcome some of the following disadvantages:
- A small number of minerals that can be absorbed through the leaves
with trace elements, N, P, and K are only about 10%, so this method is not
popular with macronutrients.
- Easily washed away from leaves when it rains and leaves is burned
when spraying at high temperature. Therefore, using foliar fertilizers should be
combined with surface adhesives and pay attention to the weather when
spraying.
- Foliar nutrition does not apply to all plants. For leaves with a thick
cuticle layer on the surface that are waterproof, foliar fertilizers will not be
effective (Nguyen Van Phu, 2002).
2.5. Research of foliar application for crops, soybean in the world and
Vietnam
2.5.1. Some results of foliar application in the world
Foliar fertilizer is effective fast, effective up to 90% nutrients. According
to Nguyen Van Phu (2001), it showed that the combination of spraying Mg and
N increases the yield of dry matter and especially the combination of N+Mg,
N+Mg+Mn, N+Mg+Zn increase the yield of wheat 30-30.9%. If Mg, N+Mg is
applied it will increase chlorophyll content in leaves, increase dry matter

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