Nghiên cứu sự biến động của vi sinh vật có ích trong đất và sâu hại chính dưới tác động của bón phân hữu cơ vi sinh và một số biện pháp kỹ thuật canh tác trên giống chè LDP1 tại phú thọ tt tiếng anh

THAI NGUYEN UNIVERSITY
UNIVERSITY OF EDUCATION

VU NGOC TU

STUDY THE VARIATIONS OF BENEFICIAL
MICROORGANISMS IN SOIL AND PESTS ON LDP1
TEA PLANTS IN PHU THO PROVINCE UNDER THE
IMPACT OF MICROBIAL ORGANIC FETILIZER
AND SOME FARMING TECHNIQUES
Speciality: Ecology
Code: 9420120

DISSERTATION SUMMARY

THAI NGUYEN - 2019


The dissertation was finished at:
THAI NGUYEN UNIVERSITY - UNIVERSITY OF EDUCATION

Supervisors:
1. Assoc. Prof. Dr. Nguyen Van Toan
2. Assoc. Prof. Dr. Le Tat Khuong

Reviewer 1:………………………………………………

Reviewer 2:………………………………………………

Reviewer 3:……………………………………………….

The dissertation will be defended in the university committee:
THAI NGUYEN UNIVERSITY - UNIVERSITY OF EDUCATION
At ……………….., 2019

The dissertation can be read at:
- National library of Vietnam;
- Thai Nguyen University - Learning Resource Center;
- Library of University of Education.
LIST OF PUBLICATIONS RELATED TO THE THESIS


1. Tran Dang Viet, Vu Ngoc Tu (2015), "Research on mechanic
harvesting technology for tea variety LDP1 on the mature
ages". Vietnam journal of agricultural science and technology,
Vietnam Academy of Agricultural Science. Vol 5(58): 33-38.
2. Vu Ngoc Tu, Nguyen Van Toan (2017), "Effects of Microbial
Organic Fertilizer and Mulch to Population and Bioactivity of
Beneficial Microorganisms in Tea Soil in Phu Tho, Viet Nam".
International Journal of Agricultural Technology 2017. Vol.
13(4): 469-484. Available online
ISSN 1686-9141.
3. Vu Ngoc Tu, Nguyen Van Toan (2018), "Impact of organic
micro-fertilizers on main pests population on Phu Tho tea".
Journal of Science and Technology, Thai Nguyen University.
Vol 180(04): 181 - 186.
4. Vu Ngoc Tu, Nguyen Van Toan, Le Tat Khuong (2018),
“Effects of multiple-purpose shading trees on some main pests
of Phu Tho tea”. Vietnam Journal of Agricultural Science and
Technology, Vietnam Academy of Agricultural Science. Vol
12(97)/2018: 82-88.

1
PREAMBLE
1. The urgency of the thesis
Tea is one of the most consumed beverage in the world and
produced from the leaves of Camellia sinensis. Applying organic
fertilizer, especially microbial organic fertilizer, will provide
nutrients for plants and supply soil microorganisms. The
development and activity of soil microorganisms greatly affect
soil quality and plant growth. Using organic fertilizer increases
organic matter and microbial activity, releases gradually
nutrients, not increasing nitrogen levels in plant tissue. In
addition to fertilizing, farming measures such as mulch, plucking
and planting shade trees also affect the growth of tea plants and
affect the quality of tea shoots.
Soil cover or mulch is to cover organic or inorganic materials on
the soil surface in order to reduce weed growth, to protect soil
moisture, to protect soil from erosion, to speed up the infiltration, and
to reduce fluctuations in soil temperature, thus increasing the growth
of plants.
Plucking of tea is both a harvesting operation and a technical
measure that greatly affects the yield and quality of tea shoots.
Besides, planting shade trees helps tea plants grow better, increase tea
production, improve soil and limit pests and diseases.
LDP1 is a tea cultivar with good growth, relatively high shoot
yield, ability to tolerate adverse conditions and pests well. Shoots of
LPD1 are used for processing both green tea and black cover with
good quality.
In order to improve the quality of tea products towards a

sustainable tea production and to enhance the value of the tea
industry, "Study on the effect of microbial organic fertilizer and some
farming measures on variation of soil beneficial microorganisms and
pests on LDP1 tea in Phu Tho" is essential to be able to propose
positive solutions for tea production in Phu Tho in particular and the
country in general.
2. Objectives of the study
- Determining the impact of microbial organic fertilizer on the
variation of some beneficial microorganisms in soil and the


2
development of some pests on tea which used as a basis for proper
fertilization.
- Determine the effect of some technical measures to the
variation of some beneficial microorganisms in soil and pests to
improve the yield and quality of tea and to reduce the development
of pests.
3. New contribution of the thesis
From the obtained research results, the thesis has some new
contributions to science those are: (1) Provide specific information
on the variation of microorganisms and increasing the quality of tea
soil under the impact of microbial organic fertilizer; (2) Using Guot
to mulch for tea plants, the number of bacteria has increased
rapidly, mulching material has been quickly decomposed, thus
helping to improve the soil in a short time; (3) Applying tea
plucking method by machine helps to increase tea yield and reduce
the harmful effects of some pests on tea such as green leaf hoppers,
thrips and tea mosquito bugs.
4. The layout of the thesis

The main content of the thesis is shown in 134 pages, including
3 preamble pages, 41 overview pages, 11 pages of materials, contents
and research methods, 79 pages of research results, discussion,
references. The whole section consists of 36 tables, 10 figures and
graphs. The appendix includes the tea production, tea consumption in
Vietnam and in the world and other contents related to the thesis.
Chapter 1. OVERVIEW
In this chapter, the thesis summarizes the research results and
outlines the general assessment of the content of the researches as
follows:
- Using organic fertilizer, especially microbial organic fertilizer
and the application of farming measures all affect soil quality,
growth, development and crop yield, from annual crops to perennials,
as well as the generation of some pests.
- For the tea plants, the research results show that use of organic
fertilizer increases the growth of tea plants and increases tea yield.


3
Applying of organic fertilizers leads to diverse microbial populations
and also increase the number of soil microorganisms.
- Mulching by organic materials (straw, grass, sawdust, crop
residues, ...) help to moisturize soil, regulate soil temperature,
improve organic matter in soil, change the population of
microorganisms and enzyme activity in the soil, thereby increasing
soil fertility and increasing crop yield and quality. The technique of
tea plucking is one of the most important factors which is interested
in tea harvest, because it is related to the yield and quality of fresh tea
leaves. The research results show that different tea plucking
techniques lead to different yield and quality.

- Using "muong la nhon" (Indigofera zollingeriana Miq.) or
mondo grass (Ophiopogon japonicus Wall) as shade trees in tea
fields to decrease problems with some pests is reported. The
research results show that shade trees affect the generation of
different tea pests.
- Although studies on the effect of organic fertilizer on tea plants
has been performed, the deep researches on the effect of organic
fertilizer, especially microbial organic fertilizer on the population of
soil microorganisms, in particular, pointing out the change in the
number of microorganism groups such as bacteria, actinomycetes or
bioactive microorganisms when applying these fertilizers on tea soil
in Vietnam is still very limited. Similarly, studies of the effect of
organic fertilizer on the variation of pests to tea plants over the time
of the year are also not popular.
- The effects of shade trees on the tea yield and quality and some
pests have also been studied. However, this research direction on
LDP1 tea plants (> 5-years old plants) in Phu Tho has not been
implemented.
Chapter 2. MATERIALS, CONTENTS
AND RESEARCH METHODS
2.1. Research materials
Tea cultivar: LDP1 tea cultivar grown in 2000 was used in the
experiments.
Other materials:
- Microbial organic fertilizer used in the study is composted
from straw, green-manure plants, microbial products containing
Actinomycetes decomposing cellulose, Bacillus and Azotobacter
converting organic matter. Quality of product: moisture content of

4
26%, organic content of 24%, total N content of 3.8%, density of
microorganisms decomposing cellulose 2.1 x 108 CFU/g; density of
Bacillus and Azotobacter 3.09 - 5.12 x 108 CFU/g.
- Song Gianh microbial organic fertilizer produced by Song
Gianh Corporation has components: moisture of 30%, organic of
15%, P2O5 of 1.5% , humic acid of 2.5%, medium components (Ca ,
Mg, S), beneficial microorganisms: Aspergillussp., Azotobacter,
and Bacillus.
- Mulch: Guot and tea tree wastes have been used as mulching
materials.
- Shade trees: "Muong la nhon" aged 4-5. Chinaberry were
planted along the border with the distance between plants from 710m (trees with a height of 5-7m).
Research subjects:
- Microorganism groups in soil are interested in research:
bacteria, actinomycetes, fungi.
- Some pests on tea plants including red spider mite, tea
mosquito bugs, green leaf hoppers, thrips.
2.2. Location and time of study
- Location: Northern Mountainous Agriculture and Forestry
Science Institute (Phu Ho commune, Phu Tho town, Phu Tho
province).
- Time for monitoring experiments: From December 2012 to
December 2015.
2.3. Research contents
Content 1: Study the effect of the amount of microbial organic
fertilizer on the variation of beneficial microorganisms in soil and
pests on tea plants in Phu Tho.
Content 2: Study the effect of mulch materials on the variation
of beneficial microorganisms in soil.

Content 3: Study the effect of harvesting methods on the
variation of pests on tea plants and the yield, quality of tea.
Content 4: Study the effect of shade trees on the variation of
pests on tea plants and the development of tea plants.
2.4. Research methods
2.4.1. Experiments:


5
* Experiment 1: Effect of the amount of microbial organic
fertilizer on the variation of beneficial microorganisms in soil.
* Experiment 2: Effect of replacing mineral fertilizer by
microbial organic fertilizer (calculated by amount of fertilizer) on the
variation of pests on LDP1 tea cultivar.
* Experiment 3: Effect of replacing mineral fertilizer by
microbial organic fertilizer (calculated by value of fertilizer) on the
variation of pests on LDP1 tea cultivar.
* Experiment 4: Effect of mulch materials on the variation of
beneficial microorganisms in soil.
* Experiment 5: Effect of harvesting methods on the variation of
pests on tea plants and the yield, quality of tea.
* Experiment 6: Effect of shade trees on the variation of pests on
tea plants and the development of tea plants.
2.4.2. Methods
* Study the effect of microbial organic fertilizer on the variation
of beneficial microorganisms in soil.
+ Research methods of microorganisms in soil:
- Soil sampling method: Soil samples were taken at a depth of 6
- 15 cm, after removing about 5 cm of soil and plant residues.
- Methods of isolation and determination of microbial cell

numbers
- Method of determining strains of microorganisms which are
able to decompose cellulose, phosphate and free nitrogen fixation
+ Experimental layout method: experiments were arranged in a
completely random block, 3 replicates, each experiment had an area
of 45 m2.
+ Adding organic fertilizer:
- Adding once at the beginning of the year (in February), at the
time of rain, moist soil. Fertilizer was added into a hole which is
close to the stump (15-30cm far from the stump, 10-15cm deep hole).
* Study the effect of the amount of microbial organic fertilizer
on the variation of pests on tea plants
+ Methods of investigating the composition and popularity
of pests:
Conducting the survey every 7-10 days, randomly surveying at 5
diagonal points, each point takes 2 small points, each small point on a


6
tea line is 1.0m long (equivalent with 3 tea plants), use a large plastic
bag to cover the tea plant and vibrate for all organisms to fall in and
then conduct counting and classification. Determine the frequency of
encountering each pest.
* Study the effect of mulch materials on the variation of
beneficial microorganisms in soil
Mulching method: evenly spread mulch materials along the
tea row, close to the tea stump. For tea leaves and branches after
cutting, they were removed from the surface and mulched
immediately to the stump.
* Study the effect of harvesting methods on the yield, quality of

tea and the variation of pests on tea plants
- Monitoring of agronomic indicators: shoot density, mass of
shoot, productivity of fresh tea shoots, ratio of tea with A+B quality,
indicators of pest density,...
2.5. Data analysis
Statistical analysis was performed by using R software. In order
to determine whether the experimental formulas which were
statistically different, Tukey (P <0.05) comparison was used to test
the difference between average values.
Chapter 3. RESULTS AND DISCUSSION
3.1. Effect of the amount of microbial organic fertilizer on the
variation of beneficial microorganisms in soil and pests on tea
plants in Phu Tho
3.1.1. Physical and chemical properties of tea soil
The results show that soil used in the experiments is acidic and
poor nutrient. pHKCl fluctuates in the range of 3.6-4.6, total and
digestible phosphate (P2O5) are low, organic matter (OM), potassium
(K2O) and protein at average level. Low CEC, from 4.12 to 6.69
meq/100g soil; low Ca and Mg, 1.59 and 0.72 meq/100g soil,
respectively. These results are consistent with previous studies.


7
3.1.2. Effect of the amount of microbial organic fertilizer on the
variation of beneficial microorganisms in soil
3.1.2.1. Effect of microbial organic fertilizer on total
microbial composition

 Effect of microbial organic fertilizer on total bacterial density

Figure 3.1: Effect of microbial organic fertilizer on total bacterial
density (unit: 106CFU/g soil). Different lower case letters indicate
significant differences among treatments at the same day and different upper
case letters indicate significant differences among days at P < 0.05. CT1
(control): No organic fertilizer; CT2: adding microbial organic fertilizer at
1.0 tons ha-1 year-1; CT3: adding microbial organic fertilizer at 2.0 tons ha-1
year-1; CT4: adding microbial organic fertilizer at 3.0 tons ha-1 year-1.
During the 60 days after applying fertilizer, the total bacterial density
in soil at the experiments began to increase, with the highest density in CT4.
After 240 days, the total bacterial density continued to increase in all
experimental treatments, the highest density in CT4 (reaching 14.3 x
106CFU / g soil) but an increase of total bacterial density in CT2 and CT3
was slowed down, gradually stabilized at over 9.80 x 106CFU / g soil.


8

Effect of microbial organic fertilizer on total actinomycetes density
Figure 3.2: Total actinomycetes density in soil (Unit: 105CFU/g soil).
Different letters indicate significant differences among treatments at the
same day at P < 0.05

The results showed that the density of actinomycetes in CT2,
CT3 and CT4 increased after 120 days of applying microbial organic
fertilizer and increased compared to control. Particularly in CT4, the
density of actinomycetes increased faster, only after 60 days. After
240 days, in the treatments adding large amounts of fertilizer (CT4),
the density of actinomycetes significantly increased, reaching 10.67 x
105CFU / g soil, while the density of actinomycetes in the control
does not change. In the treatments applied lower microbial organic

fertilizer, such as CT2 and CT3, the density of actinomycetes was
also increased compared to the control but still lower than that of
CT4 after 240 days.
 Effect of the amount of microbial organic fertilizer on the density
of bioactive microorganisms
Of the 10 tested strains of bacteria in CT4, up to 46% of strains
had cellulose decomposing activity; the number of the strains
decomposing insoluble phosphates, starch and mucous membrane
was 32%, 22% and 15%, respectively. The number of
microorganisms decomposing cellulose, insoluble phosphates in CT2
and CT3 was lower, even many strains which are not able to
decompose starch and mucous membrane were also detected in these
treatments
3.1.2.2. Assession of the diversity of microorganisms in soil under the
impact of microbial organic fertilizer


9
Table 3.1: The diversity of microorganisms in soil after applying
microbial organic fertilizers (240 days)
Treatments

Genus
total

CT1
CT2
CT3
CT4

8
15
16
24

Bacteria

Filamentous
fungi

Number

%

Number

4
8
8
14

50
53.3
50
58.33

0
1
2
6

%

Lipomyces

Actinomycete

Number

%

Number

%

0
2
2
2

0
13.33
12.5
8.3

4
4
4
2

50
26.67
25
8.33

0
6.67
12.5
25

Data in Table 3.1 show that the most diversity of
microorganisms was observed in CT4 with 24 genera, of which 14
genera of bacteria (accounting for more than 58%), filamentous fungi
accounts for 25%. The number of microorganism varieties in CT2
and CT3 is similar (15 and 16 genera), and higher compared to CT1
(8 genera).
Table 3.2: Soil microbial composition and their distribution
in treatments applying microbial organic fertilizer
(after 240 days)
Groups

Composition of
varieties

Pseudomonas
Bacillus
Cellulomonas
Cellulose - and insoluble
Agrobacterium
phosphates

Enterobacter
-decomposing bacteria,
Nitrosomonas
and nitrogen-fixing
Nitrobacter
bacteria
Azotobacter
Mycobacterium
Rhizobium
Aspergillus
Penicillium
Filamentous fungi
Trichoderma
decompose cellulose and
Fusarium
insoluble phosphates
Mucor
Mertahzium
Actinomycetes
Actinomycetes
producing antibiotics
Lipomyces producing
Lipomyces
polysacharide
Total
18

Frequency of occurrence of
strains
T1

(control
)
++
+++
+
+
+
+++
+++

T2

T3

T4

++
+++
+++
+
+
+
++
+
++
+++
+
+
++
+

+++
++++
++
++
++
+
++
++++
++++
++
+++
++
+
++

++++
++++
++++
+
+++
++++
++++
+++
++
++
++
++
++
+

+
+
++

+

+

-


10
Note: So many: (++++), many: (+++), relative: (++), less: (+), and none: (-)

Table 3.2 shows that applying more microbial organic
fertilizers (CT4) in soil leads to appear many strains of
bacteria decomposing organic matter, cellulose, and
insoluble phosphates such as Pseudomonas, Bacillus,
Azotobacter, Nitrosomonas and Nitrobacter.

3.1.3. Effect of the amount of microbial organic fertilizer on the
variation of pests on tea plants
3.1.3.1. Investigation of the composition of pests and natural enemies
on tea plants in Phu Tho

 The composition of pest on tea plants in Phu Tho
The survey results show that there are 29 pest species on tea
plants in Phu Tho, belonging to 9 orders of insects and spiders,
including:
- Order Acarina: There are 5 species of 4 families, of which the

main harm species is Oligonyclus coffeae Nietner.
- Order Coleoptera: There are 2 species of 2 different families
Curculinidae and Scarabacidae, notably dor-beetles that damage tea roots.
- Order Diptera: 1 species of Chloropidae family
- Order Hemiptera: there are 5 species of 4 families, notably tea
mosquito bugs Helopeltis theivora Waterhouse seriously harms tea.
- Order Homoptera: There are 4 species of 4 families, of which
Empoasca flavescens Fabr. belongs to Ciadellidae which accounts the
largest number, then to the mealybug.
- Order Isoptera: 1 species Odontotermes formosanus Shiraki
belongs to Termitidae family.
- Order Lepidoptera: There are 8 species of 7 families
- Order Orthoptera: 2 species of 2 families, these species of this
order do not cause significant harm.
- Order Thysanoptera: 1 species Physothrips setiventris Bagnall of
Thripidae family.
 The composition of natural enemies of pests on tea in Phu Tho


11
In the beginning of 2013, investigation and evaluation of natural
enemies of pests on tea in Phu Tho has obtained 19 species of insects,
prey spiders and parasites, belonging to 8 different orders.
Table 3.3: The composition of natural enemies of pests on tea in
Phu Tho
No
.

Vietnamese
name

Science name

Order Acarina
Nhen
nho
Amblyseius sp.
bat moi
Order Araneida
Clubiona japnicolla
2. Nhen gap la
Boes. et Str.
Tetragnatha
3. Nhenhamdai
maxilloxa Thorell
1.

4.

Nhenlinhmieu

Family

Phytoseiidae
Clubionidae
Tetragnathida
e

Oxyopes
Oxyopidae

javanus Thorell

Atypena
Linyphiidae
formosana sp.
Pardosa
6. Nhen soi
pseudoannulata Lycosidae
Boes. et Str.
Nhen van lung Argipe catenulata
7.
Araneidae
hinh mac
Doles chall
Order Coleoptera
Kien
ba Paederus
Strophylinida
8.
khoang
fuscipes Curtis e
Micrapis
9. Bo rua do
Coccinellidae
discolor Fabr.
5.

Nhen lun

10. Bo rua nho

Stethorus sp.

Menochilus
sexmaculatus
Fabr.
Bo rua chua Coccinella
12.
nhan
transversalis
Order Diptera
Ischiodon
13. Ruoi an rep
scutellaris Fabr.
Order Hemiptera
Orius
sauteri
14. Bo xit an sau
Popius
Order Hymenoptera
Ong
ken
15.
Apanteles sp.
trang nho
16. Ong ky sinh Lysiphlebus sp.
11. Bo rua 6 van

Coccinellidae

Prey

Popularity

Small spider mite

+

Green leaf
hoppers
Green leaf
hoppers
Green leaf
hoppers, larva of
Lepidoptera
Green leaf
hoppers

+
++
++
+

Green leaf
hoppers

+

Green leaf
hoppers, thrips

+

Aphids, larva of
Lepidoptera
Aphids, larva of
Lepidoptera
Aphids,
green leaf
hoppers

++
++
+

Coccinellidae

Aphid, green leaf
hoppers

+

Coccinellidae

Aphids, their
eggs

+

Aphids

+

Thrips,Aphid eggs

+

Syrphidae
Anthocoridae
Braconidae
Aphidiidae

Homona
coffearia Niet.
Aphids

+
+


12
No
.

Vietnamese
name

Science name

Family

Prey

Popularity

rep
Ong vang ky Xanthopimpla
Ichneumonida Pupa17.
+
sinh nhong
sp.
e
Lepidoptera
Order Mantodea
Empusa
Aphid, tea
18. Bo ngua
Mantidae
+
unicornis
mosquito bugs
Order Odonata
Agriomis
Chuon chuon
Baby worm,
19.
femina femina Coenagridae
++
kim
Scab

Brauer
Note:+ Less popular (<30%); ++Relatively popular (30-60%); +++ Very popular (>60%)

3.1.3.2. Effect of replacing mineral fertilizer by microbial organic
fertilizer (calculated by amount of fertilizer) on the variation of pests
on LDP1 tea cultivar

 Effect of replacing mineral fertilizer by microbial organic
fertilizer on the variation of green leaf hoppers on LDP1 tea
In the years of 2013-2015, it showed that the density of green
plant hoppers was relatively low in January, the density began to
increase in February and increase rapidly in March, April, peaking in
May. The density of green plant hoppers decreased gradually in June,
July and August, then increased back in September and October and
gradually decreased from November to December

Figure 3.3:Variation of the density of green leaf hoppers in 20132015 (No. of individuals/tray). Asterisks indicate significant differences
among experimental treatments compared to control at the same month at P
< 0.05. CT1 (control): 300 N + 100 P2O5 + 100 K2O (Background); CT2: 70%


13
Background + 30% N by Song Gianh microbial organic fertilizer; The
dosage of 30% N converted by Song Gianh microbial organic fertilizer is
1600 kg/ha/year. Apply twice a year.

The density of green leaf hoppers (young ones) and the rate of
demaged shoots were highest in May in all three treatments. At this
time, the density of green leaf hoppers and the rate of damaged
shoots were lowest in CT3 (10.3 per tray) and highest in CT1 (14.3

per tray). After that, the density of green leaf hoppers decreased
gradually from June and increased back in October.

 Effect of replacing mineral fertilizer by microbial organic
fertilizer on the variation of thrips on LDP1 tea
In the first month of the year, the thrips density is very low and
increases gradually in February, March, and April. From June, the
number of thrips increased rapidly and peaked in August. Then the
density of thrips reduced and was at low level in November and
December. According to experimental results (Figure 3.4), the
density of thrips is lowest in CT3 and highest in CT1 (control),
especially in months like July and August. In August, the number of
thrips is highest in CT1 with 6.19 individuals/shoot, while this
number in CT3 is 4.31 individuals/shoot.

Figure 3.4: Variation of the density of thrips in 2013-2015 (No. of
individuals/shoot). Asterisks indicate significant differences among
experimental treatments compared to control at the same month at P < 0.05.


14
Harm caused by thrips on tea shoots was also investigated and
evaluated, as shown in Table 3.4.
Table 3.4: The mass of damaged tea shoots at different levels
C0 level
C1 level
C2 level
C3 level
Treatment
(g/shoot)

(g/shoot)
(g/shoot) (g/shoot)
CT1
0.80a
0.76a
0.54a
0.48a
ab
b
b
CT2
0.82
0.80
0.72
0.60b
CT3
0.84b
0.80b
0.66c
0.57b
Note: Different letters indicate significant differences among experimental
treatments at the same level at P < 0.05

When only applying inorganic fertilizer (CT1), the mass of tea
shoots at all levels is lower than that in experiments using microbial
organic fertilizer (CT2 and CT3). The application of a part of
microbial organic fertilizer as in CT2 and CT3 helps to significantly
reduce the reduction in mass of demaged shoots, at the level C3, tea
shoot mass still reach 0.6 g/shoot, meanwhile the mass of tea shoots
at level C3 in the control is only 0.48 g/shoot.

 Effect of microbial organic fertilizer on natural enemies on
LDP1 tea
Analysis of natural enemies on tea fields at the
time of outbreaks of green leaf hoppers and thrips
(from May to October) shows that: The most common is the
species of Araneida (34 species), followed by Coleoptera with 17
species, Hymenoptera of 12 species (mainly bees, ants eating meat,
mason bee).
 Effect of microbial organic fertilizer on the density of natural
enemies
Investigation of changes in natural enemy density observed in
experimental plots found that natural enemies appeared less in March
annually, with two periods appearing many natural enemies are May
to August and October to November. The density of natural enemies
appeared most in August (1.68 individual/tray in CT1; 1.72
individual/tray in CT2 and 2.16 individuals/tray in CT3) and the


15
lowest in March (for CT1, CT2, CT3 are 0.58, 0.85 and 0.78
individual/tray, respectively).
3.1.3.3. Effect of replacing mineral fertilizer by microbial organic
fertilizer (calculated by value of fertilizer) on the variation of pests
on LDP1 tea cultivar.

 Effect of replacing mineral fertilizer by microbial organic
fertilizer (calculated by value of fertilizer) on the variation of green
leaf hoppers
The variation of green leafhopper density in CT1 obeys the

general rule which appears less in the first months of the year
(January and February) and increases rapidly from March, then peaks
in May and June (13.25 individuals/tray and 11.40 individuals/tray,
respectively). From July, the number of green leaf hoppers decreased
gradually and reached the lowest level in December (1.52
individual/tray). Thus, the replacement of synthetic fertilizers with
Song Gianh organic microbial organic fertilizer in CT2 and CT3
leads to a reduction in the density of green leaf hoppers in most
months, especially in May.
 Effect of replacing mineral fertilizer by microbial organic
fertilizer (calculated by value of fertilizer) on the variation of thrips
The density of thrips at the experimental plots increase gradually
from January, February and peaks in June, then decrease and lowest
in the last months of the year (October, November and December).
However, at different times, the variation of the thrips' density is
different. For CT1 (control), the months of June, July and August are
the time appearing most thrips, of which density is the highest in
June (4.81 individuals/shoot). The density of thrips reaches peak in
June in CT2 and CT3 (4.54 and 4.15 individuals/shoot, respectively,
but it is still lower compared to CT1 (4.81 individuals/shoot). The
replacement of 30% mineral fertilizers (calculated by value of
fertilizer) by Song Gianh microbial organic fertilizer in CT3 may
have a positive impact on tea plants, increase resistance and help
plants grow better, contributing to limit the generation of pests
(including thrips).


16

 Effect of replacing mineral fertilizer by microbial organic

fertilizer (calculated by value of fertilizer) on the variation of natural
enemies on LDP1
Investigating the composition of natural enemies in the
experimental plots found that the species of natural enemies were
identified in 10 orders, mainly belong to Coleoptera (with 14
species), Hymenoptera (10 species) and Araneida (28 species).
Species belonging to Neuroptera, Hemiptera, fungi, ... appear less
(only 1-2 species/order).
3.1.4. Effect of microbial organic fertilizer on physicochemical
properties of tea soil
Table 3.5: Physical properties of soil before and after applying
microbial organic fertilizer for three years
Content

Parameters

Before
1.36a
2.63a
48.3a
33.5a

Bulk density (g/cm3)
Density (g/cm3)
Porosity of soil (%)
Field capacity (%)

After
1.09b
2.48a

52.6b
42.1b

The results show that after using microbial organic fertilizer,
bulk density has decreased from 1.36 to 1.09g/cm3, the soil density
has also improved, decreasing from 2.63 to 2, 48 in the area applying
microbial organic fertilizer.
Table 3.6: Chemical properties of soil before and after
applying microbial organic fertilizer for three years
Parameters
N (%)
P2O5 (mg/100g)
K2O (mg/100g)
Organic
matter
(%)

Before
0.08a
2.9a
7.34a
2.56a

After
0.1b
4.13a
7.94a
2.72a

3.1.5. Effect of microbial organic fertilizer on the

parameters in tea yield
Table 3.7: Effect of microbial organic fertilizer on the
components of tea yield
Treatment

Shoot density

Shoot mass

Theoretical


17

CT1
CT2
CT3
CT4

(shoot/m2)
161.3a ± 3.8
169.4b ± 2.3
171.7b ± 2.4
174.2b ± 2.1

(gam/shoot)
0.67a ± 0.01
0.68a ± 0.017
0.70a ± 0.011
0.71b ± 0.016

yield (ton/ha)
9.51a
10.22b
10.63b
10.88b

Note: Shoot density and mass of tea shoots were monitored in the spring season.
Letters indicate significant differences among treatments at P <0.05. CT1 (control):
No microbial organic fertilizer; CT2: applying microbial organic fertilizer at 1.0
tons/ha/year; CT3: applying microbial organic fertilizer at 2.0 tons/ha/year; CT4:
applying microbial organic fertilizer at 3.0 tons/ha/year.

Using microbial organic fertilizer had a positive effect on the
number of beneficial microorganisms in soil, improving the physical
and chemical properties of the soil. Tea yield is the highest in CT4
which used the largest amount of microbial organic fertilizer and in
this treatment the number of microorganisms was the highest with the
most diverse composition.
3.2. Effect of mulch materials creating soil organic matter on the
variation of beneficial microorganisms in soil
3.2.1. Effect of mulch materials on microbial composition in soil
3.2.1.1. Effect of mulch materials on total bacterial density
In CT1, mulch material was not used, total bacterial density
was the highest 8.02 x 10 6 CFU/g soil. But in CT2, the variation of
total bacterial density took place rapidly at stage of 180 days and
270 days.
Table 3.8: Total bacterial density before and after mulching
(Unit: 106CFU/g soil)
Treatment

CT1
CT2
CT3

0
7.92 ± 0.22a
7.90 ± 0.53a
7.90 ± 0.45a

Number of mulching days
90
180
270
7.90 ± 0.26a 8.02 ± 0.42a 8.00 ± 0.38a
8.45 ± 0.2b 9.56 ± 0.56b 11.30 ± 0.41b
8.00 ± 0.58a 8.43 ± 0.45a 10.86 ± 0.44b

Note: Letters indicate significant differences among treatments at the same time at P
<0.05. CT1 (control): Non-mulching; CT2: mulching by Guot, 30 tons/ha/year; CT3:
mulching by tea tree wastes, 30 tons/ha/year.


18
3.2.1.2. Effect of mulch materials on total actinomycetes density
Table 3.9: Density of actinomycetes before and after mulching
(Unit: 105CFU/g soil)
Number of mulching days
Treatment
0
90

180
270
CT1
6.24 ± 0.25a 6.20 ± 0.17a 6.14 ± 0.35a 6.18 ± 0.36a
CT2
6.30 ± 0.35a 7.05 ± 0.11b 8.40 ± 0.23b 9.17 ± 0.37b
CT3
6.25 ± 0.39a 8.23 ± 0.3c 9.31 ± 0.31c 11.05 ± 0.52c
Note: Letters indicate significant differences among treatments at the same
time at P <0.05.

Total actinomycetes density in CT1 (control) did not change
after 90, 180 or 270 mulching days. However, in CT2 and CT3, total
actinomycetes density increased after mulching and reached the
highest level at the longest time (270 days). The density of
actinomycetes was the highest in CT3, the density of actinomycetes
increased after 90 mulching days and reached the highest of 11.05 x
106CFU / g soil after 270 days.
3.2.1.3. Effect of mulch materials on the density of fungi
Table 3.10: Density of fungi in the samples analyzed
(Unit: 103CFU/g soil)
Treatmen
t
CT1
CT2
CT3

0
5.18 ± 0.32a
5.35 ± 0.38a

5.26 ± 0.41a

Number of mulching days
90
180
5.30 ± 0.27a
5.27 ± 0.23a
7.45 ± 0.42b
9.05 ± 0.26b
c
6.12 ± 0.21
9.26 ± 0.37b

270
5.24 ± 0.43a
8.04 ± 0.37b
9.34 ± 0.24c

Note: Letters indicate significant differences among treatments at the same
time at P <0.05.

In CT2, after 90 days of mulch, the fungus system increased
from 5.35 x 103CFU/g soil to 7.45 x 103CFU/g soil, then continued to
increase strongly in the next 90 days and stabilize later. From this
result, it can be seen that mulching material stimulated the fungal
system to develop and diversify the microorganism system in tea soil.
3.2.1.4. Effect of mulch materials on the biological activity of some
microorganism groups
Of 10 strains tested biological active, the percentage of bacteria
which is able to decomposing cellulose well accounts for 40% in CT2

19
and CT3. The percentage of bacteria decomposing insoluble
phosphate at relatively good level reached at 44% in CT2, much
higher than in CT1 (16%) and CT3 (38%), but the percentage of
bacteria decomposing insoluble phosphate at good level in CT2 was
the lowest (only 5% in CT2 compared to 12% and 16% in CT1 and
CT3, respectively). For actinomycetes, the percentage of
actinomycetes which are able to decomposing cellulose, insoluble
phosphate,... in CT3 was higher than that in other treatments.
3.2.2. Effect of mulch materials on the diversity of soil
microorganisms
22 species were identified in the analyzed samples. Of the 22
species, 12 species belong to the microbial group, 8 species belong to
the group of filamentous fungi, one species belongs to the
actinomycetes and one is in Lipomyces producing polysacharide. The
frequency of occurrence of strains was higher in CT3 (used tea tree
wastes to mulch) than in CT2 (used Guot as mulching material) and
CT1 (control). Notably, Actinomyces group producing antibiotics
strongly developed in CT3. In contrast, Lipomyces producing
polysacharide was more abundant in CT2 than in CT3.
3.3. Effect of harvesting methods on the variation of pests on tea
plants and the yield, quality of tea
3.3.1. Effect of harvesting methods on the variation of pests
Table 3.11: Effect of tea plucking techniques on pests

Experiments

Green leaf

hoppers
(individual/
tray)

Hai san trat
Hai ky
Machine
plucking

The density of pests
Red
Tea mosquito
Thrips
spider
bugs
(individual/
(% demaged shoots)
mite
shoot)

(individual/
leaf)

7.69a
6.61b

1.99a
1.41b

2.38a

2.35a

5.81c

1.06b

1.49b

6.73a
4.61b
2.93c


20
Note: Hai san trat: hand plucking every 7-10 days; Hai ky: hand
plucking every 20-28 days. Letters indicate significant differences among
experiments at P <0.05.

* For green leaf hoppers: the density of green leaf hoppers was
the lowest as applying machine plucking, the average density reached
5.81 individuals/tray.
* For thrips: the density of thrips at "hai san trat" was the
highest with 1.99 individuals/shoot, followed by "hai ky" with
average density of 1.41 individual/shoot, and the density was the
lowest as applying machine plucking with 1.06 individual/shoot.
* For tea mosquito bugs: The degree of damaged tea is most
severe in the "hai san trat" and the lightest in the machine plucking.
The percentage of shoots damaged in average level in "hai san trat"
and "hai ky" was 6.73% and 4.44%, respectively, while this
percentage in machine plucking was 2.93%.

* For red spiders mites: the density of red spider mite in
machine plucking was 1.49 spider/leaf, which was lower than that in
"hai san trat" (2.38 spiders/leaf) and "hai ky" (2.35 spiders/leaf). Red
spider mite density increased from September to November and
ranged from 1.37 to 4.82 spiders/leaf in the experiments.
3.3.2. Effect of harvesting methods on the parameters in tea yield
Table 3.12: The results of analyzing the parameters in LDP1
yield in the different experiments
Experiments

The parameters in tea yield
Plucking times Shoot density Shoot mass
(time)
(shoot/m2)
(gam/shoot)
a
15
1696.6 ± 111.2
0.70a
a
7
1708.6 ± 97.1
0.69a

Yield
(ton/ha)

Hai san trat
9.68a
Hai ky

9.49a
Machine
4
1638.6a ± 88.9
0.83b
11.09b
plucking
Note: Letters indicate significant differences among experiments at P <0.05.

* When applying "hai ky", the number of plucking times was 7,
the shortest time between the two plucking times is 20 days, the
longest time is 28 days, and the average of 24.2 days /time. When


21
applying machine plucking, number of plucking times significantly
reduced to 4 times, the shortest time between the 2 plucking times
was 37 days, the longest was 45 days, the average was 42.4
days/times. Time to end plucking as applying the machine plucking is
earlier 13-15 days than applying hand plucking.
* Tea yield: The tea yield in "hai san trat" was 9.68 tons/ha and
in "hai ky" was 9.49 tons/ha, which is similar to 97.85% compared to
"hai san trat". In the experiment using machine plucking, the yield
reached 11.09 tons/ha, increasing 14.64% compared to "hai san trat".
3.3.3. Effect of harvesting methods on quality of fresh tea materials
The percentage of tea materials with the quality of A+B type in
"hai san trat" was the highest (64.4%), type C accounts for 33.2%,
type D is 2.4%, and other parts like stems, branches, and old leaves
are removed. In the treatment of "hai ky", the percentage of tea
materials in the groups was 43.2% (type A + B), 44.2% for type C

and 12.6% for type D. In the treatment of machine plucking, type C
and D accounted for 86.6%, the remaining of 13.4% including the
stems, old leaves were still in the materials.
3.4. Study the effect of shade trees on the variation of pests on tea
plants and the development of tea plants
3.4.1. The effect of shade trees on some pests on tea plants
3.4.1.1. The variation of green leaf hoppers in the experiments
Green leaf hoppers seriously damage in the period of tea growth,
from March to October and they appear most in July, August and
September. However, the density of green leaf hoppers in CT2 and CT3
was less than in CT1, especially in August and September. Specifically,
the density of green leaf hoppers in CT1 reached 20.8 individuals/tray in
August and 18.3 individuals/tray in September, while the density of
green leaf hoppers in CT2 was 14.4 individuals/tray in August and 9.85
individuals/tray in September, this density in CT3 was 16.38


22
individuals/tray in August and 13.62 individuals/tray in September. This
difference is statistically significant.
Table 3.13: Differences in the density of green leaf hoppers in
the experiments (No. of individuals/tray)
Year
CT1
CT2
CT3
2014
10,02aA
9,42aA
9,67aA

2015
10,27aA
6,63bB
6,92bB
Note: Different capital letters indicate significant differences among
treatments at the same year and different letters indicate significant
differences between two years at P < 0.05.

Use of "muong la nhon" as shade trees in tea fields with a
density of 250 plants/ha reduced the density of green leaf hoppers
and this difference is statistically significant.
3.4.1.2. The variation of thrips
The density of thrips in CT2 reached the highest level in July
(3.43 individuals/shoot), in CT3 the density of thrips reached the
highest in May (4.18 individuals/shoot) and this density in both
treatments are lower than the highest density of thrips in CT1 in May
(5.44 individuals/shoot).
In May, although the density of thrips in two treatments
applying shade trees (CT2 and CT3) was lower than that in control,
the density of thrips in CT3 (4.18 individuals/shoot) was more than
that in CT2 (2.91 individuals/shoot) and this difference is statistically
significant. During other times of the year, the density of thrips in
CT2 and CT3 is always lower than that in CT1.
3.4.1.3. The variation of tea mosquito bugs
The results of investigation of tea mosquito bugs in the
treatments showed that the percentage of tea shoots demaged by
tea mosquito bugs in CT2 tends to be higher than that in CT1. Tea
mosquito bugs cause damage from April to the end of the period
of tea growth, the highest level of damage from July to November.
The percentage of damaged shoots was highest in November in all

three treatments (with 26.54% in CT2 and 24.87 in CT3 which
used shade trees and 22.93% in CT1 which did not use shade