Tóm tắt: Nghiên cứu và ứng dụng xạ khuẩn trong phòng trị bệnh đạo ôn hại lúa do nấm Pyricularia oryzae Cav. trên vùng đất nhiễm mặn

MINISTRY OF EDUCATION AND TRAINING
CAN THO UNIVERSITY

SUMMARY OF DOCTORAL THESIS
SPECIALITY: PLANT PROTECTION
Speciality ID: 62620112

DANG NGUYET QUE

RESEARCH AND APPLICATION OF
ACTINOMYCETES STRAINS FOR THE
MANAGEMENT OF RICE BLAST DISEASE
CAUSED BY Pyricularia oryzae Cav.
IN THE SALT-AFFECTED SOILS AREAS

Can Tho, 2023


THE THESIS WAS COMPLETED AT
CAN THO UNIVERSITY

Scientific supervisors 1: PGS.TS. Le Minh Tuong
Scientific supervisors 2: PGS.TS. Tran Thi Thu Thuy

Reviewer 1: Assoc. Prof, Ph.D Pham Van Du
Reviewer 2: Assoc. Prof, Ph.D Nguyen Thi Thu Nga

The thesis is defended in front of the Doctoral Thesis
Examination Council at Can Tho University.
Time: 8:00 am
Date: September 3th, 2022

Further information of the thesis could be found at:
1. Learning Resource Center of Can Tho University
2. National library of Vietnam


LIST OF PUBLISHED PAPERS
1. Dang Nguyet Que, Le Minh Tuong and Tran Thi Thu Thuy,
2019. Determination of characterictic of actinomycetes
isolates on Pyricularia oryzae causing rice blast disease on
salt afected soils. Science and Technology Journal of
Agriculture and Rural Development. Ministry of
Agriculture and Rural Development, Vietnam. May, 2019,
81-86.
2. Dang Nguyet Que, Le Minh Tuong and Tran Thi Thu Thuy,
2019. Identification of actinomycetes as promissing
biocontrol against rice blast disease in salt affected soils.
Journal of Vietnam Agriculture Science and Technology.
Vietnam Academy of Agricultural Sciences. Vol 6
(103)/2019, 125-129.
3. Dang Nguyet Que, Le Minh Tuong and Tran Thi Thu Thuy,
2021. Determination biocontrol of actinomycetes isolates
on rice blast disease on salt affected soils in the net house
condition. Đánh giá khả năng phịng trị bệnh đạo ơn hại
lúa canh tác vùng đất nhiễm mặn của một số chủng xạ
khuẩn trong điều kiện nhà lưới. Journal of Plant
Protection. Vol 5 (298)/2021, 21-27.


Chapter 1: INTRODUCTION

1.1 The urgency of thesis
Blast disease caused by the fungus Pyricularia oryzae (P. oryzae) is one
of the three major diseases that significantly affect the yield and quality of
rice worldwide (Dean et al., 2012; Gao et al., 2019; Chen et al., 2021).
Because the fungus P. oryzae attacks all parts of the rice plant, it causes
losses of up to hundreds of millions of tons of rice each year (Wang, 2009).
In Bac Lieu, rice blasts caused widespread damage in all seasons with
varying degrees of severity. Especially in salt-affected rice-shrimp fields,
blast disease occurs relatively early and spreads quickly if not sprayed in
time. Meanwhile, chemical drug use also affects the giant freshwater shrimp
intercropping in rice fields and the next shrimp rotation crop. To maintain
and develop an effective and sustainable rice-shrimp farming model and to
adapt to climate change towards safe rice and shrimp production that meets
export standards, it is necessary to research and find out biological solutions.
These must effectively manage rice blast disease, progressing to developing
an integrated rice blast disease process on saline soil in the rice-shrimp
farming system.
Regarding biological measures, the past has shown that the study of the
application of actinomycetes is considered a promising solution and has great
potential to replace fungicide to prevent blast disease towards safe
agriculture and sustainability. Many valuable scientific works on the
application of actinomycetes to control rice blast disease have been published
in national and international journals (Tuong & Em, 2014; Khalil et al., 2014;
Lan and ctv., 2015, 2016; Awla et al., 2016, 2017; Law et al., 2017; Gao et
al., 2019). However, most of the studies about actinomycetes were conducted
in the laboratory. Some studies were carried out in net houses and the field.
However, there is no research on the application of actinomycetes to prevent
and treat rice blast disease in saline soil. Therefore, the thesis "Research and
application of actinomycetes strains for the management of rice blast disease
caused by Pyricularia oryzae in the salt-affected soils area" is essential.

1.2 Research objectives and requirements
(i) Selecting salt-tolerant actinomycete strains’s ability against pathogen
P. oryzae in the laboratory.
1


(ii) Study on the antagonistic ability of actinomycetes through the ability
to secrete chitinase and β-1,3-glucanase enzymes.
(iii) Identifying the species of promising actinomycetes strains.
(iv) Evaluation capable of managing rice blast disease in the net house
conditions.
(v) Evaluating the effectiveness of managing rice blast disease of
promising salt-tolerant actinomycetes strains in field conditions.
1.3 Scientific and practical significance of the thesis
The topic has high scientific and practical significance; the project's
results are to find actinomycetes strains capable of managing rice blast
disease caused by the fungus P. oryzae on salt-affected soils. The results of
this study serve as a premise for the following studies to find probiotics from
salt-tolerant actinomycetes and apply them to the integrated management of
rice blast disease on salt-affected soils. Both are effectively and
environmentally friendly, contributing to developing a sustainable riceshrimp farming model.
1.4 The new results of the dissertation
- Three salt-tolerant actinomycetes isolates, including S06-MBL, S09MBL and S17-MBL, have been identified to prevent rice blast disease under
net house conditions. Two strains of Streptomyces bikinensis (S09-MBL) and
Streptomyces lavendulate (S17-MBL) could prevent rice blast disease in
saline soil field conditions in Bac Lieu.
- The biocontrol ability of 3 actinomycetes S06-MBL, S09-MBL and
S17-MBL against rice blast disease caused by P. oryzae was related to the
ability to secrete chitinase and β-1,3-glucanase enzymes.
- Species of 3 actinomycete strains have been identified: S06-MBL is

Streptomyces fradiae, S09-MBL is Streptomyces bikiniensis, and S17-MBL
is Streptomyces lavendulae. These species differ from previous actinomycete
species studied in managing blast disease in Mekong Delta.
Chapter 2: RESEARCH METHODS
2.1 Time and place of the thesis
- Time: from October 2015 to February 2019.

2


- Place: the laboratory and the nethouse of the Plant Protection
Department, Can Tho University; Bạc Liêu University và saline rice fields
of farmers in Hồng Dân district, Bạc Liêu province.
2.2 Experimental Materials: fungus P. oryzae causing rice blast disease
and actinomycetes
2.3 Experimental methods
2.3.1 Content 1: Collect, isolate and evaluate the pathogenicity of P.
oryzae strains causing riceblastdisease.
- Collect and isolate P. oryzae causing rice blast disease in the Mekong
Delta salt-affected soils area: Investigate and collect rice samples with blast
disease in, rice-shrimp fields in Bac Lieu, Ca Mau, Kien Giang and Hau
Giang provinces; Isolation and culture of P. oryzae fungus were carried out
at the Plant Diseases laboratory of Plant Protection Department, Can Tho
University according to the method of Burgess et al. (2009). Identification
of P. oryzae fungus was based on morphological characteristics of fungal
strains compared with those of P. oryzae described by Agrios (2005) and
Zhang et al. (2014).
- Evaluation of pathogenicity of P. oryzae isolates under the nethouse
condition: In the period of 18 days after planting, the rice plants were
artificially infected. Spraying a suspension of P. oryzae fungi spores evenly

wet the foliage with a spore density of 105 spores/ml in the fantastic
afternoon; each spraying pot is 10 ml. Pots of rice after artificial inoculation
were placed in the incubation room and covered in darkness for 24 hours (the
temperature at 260C and humidity at 96-98%). After that, the pot of rice was
transferred to the net house with a shading system to reduce 50% of light
conditions, misted to create the right humidity for fungal growth (incubation
net house). The recorded indicators were the ratio of infected leaf area and
disease index at the time of 4, 6, 8, 10, 12 and 14 days after artificial
infection.
2.3.2 Content 2: Collect, isolate and evaluate the antagonistic ability of
actinomycete isolates derived from rice saline soil against the fungus P.
oryzae strains causing rice blast disease under laboratory condition.
- Collecting and isolating actinomycetes from rice saline soil: Soil
samples were taken around the root zone of rice, 10-25 cm from the surface
3


and isolated actinomycetes at the laboratory of the Department of Plant
Protection. Can Tho University according to the method of Hsu and
Lockwood (1975).
- Evaluation of the antagonistic ability of actinomycetes against P.
oryzae causing rice blast disease under laboratory condition: Put the sterile
absorbent paper rolls into the actinomycete suspension solution (108cfu/ml),
shook the solution well. Use specialized clamps to put the absorbent paper
on the wall, let it dry. Place the blotting paper (Ø = 5 mm) impregnated with
actinomycetes opposite the P. oryzae and 1 cm from the sides of the plate. In
the control treatment, the paper strips impregnated with actinomycetes were
replaced with ones impregnated with sterile distilled water. The follow-up
indicator was to measure the radiuses of inhibition zones and calculate the
antagonistic efficiency at the time of 3, 5, 7 and 9 days after inoculation

(DAI)
- Investigation of the antagonistic ability of promising actinomycete
strains against P. oryzae under the conditions of addition of NaCl salt:
perform the same experiment as above, except that the experimental medium
is supplemented with NaCl salt (2g/l). The follow-up indicator was to
measure the radiuses of inhibition zones and calculate the antagonistic
efficiency at the time of 3, 5, 7, 9 and 11 days after inoculation (DAI).
- Investigation of the ability to inhibit the growth of spores of P.
oryzae of promising actinomycetes: Treatment of actinomycetes: Add 500
µl of actinomycete suspension (108 cfu/ml) + 500 µl of fungal suspension
(5x105 spores/ml) into eppendorft tubes and keep at 28oC, each treatment
with 4 times of replicationt. Control treatment: Put 500 µl of sterile distilled
water + 500 µl of fungal spore suspension (5x105 spores/ml) into eppendorft
tube and keep at 25oC. Recording indicators: The percentage of spores
sprouting at the time of 6, 12 and 24 hours after treatment (HAT) by
observation under the microscope.
2.3.3 Content 3: Investigate a number of mechanisms related to the
antagonistic ability of promising actinomycetes
- Investigate the ability to secrete chitinase-degrading enzyme
chitinase of actinomycete strains on agar: The experiment was arranged
in a completely randomized design with one promising actinomycete strain
4


and five replications for each treatment according to the method of Dai et al.
(2011) and Ha (2012).
- Determination of secreted chitinase enzyme content of
experimental actinomycetes: The experiment was arranged in a completely
randomized design with 5 replications and performed according to the
method of Dai et al. (2011) and Ha (2012).

- Investigation of the ability to secrete β-1,3-glucanase enzyme to
degrade β-1,3-glucan of actinomycete strains on agar: The experiment
was arranged in a completely randomized design with each treatment being
a promising actinomycete strain with 4 replicates. . The experiment was
carried out according to the method of Renwich et al., (1991).
- Determination of the secreted β-1,3-glucanase enzyme content of
actinomycete strains: The experiment was arranged in a completely
randomized design with one factor, the number of treatments was the number
of actinomycete strains tested with 4 replicates and was performed according
to the method of Renwich et al. (1991).
2.3.4 Content 4: Identify promising actinomycetes species by
observation biological characteristics methods and molecular biology
methods.
- Identification of actinomycetes based on culture, morphological
and biochemical characteristics
* Observation of the color of biogas, substrate fibers and soluble
pigments which were conducted according to the method of Shirling and
Gottlieb (1966).
* Observation of spore stalk and spore surface shape which were
conducted according to the method of Tresner et al. (1961).
* Protease secretion ability of actinomycete strains: was performed
according to the method of Mitra and Chakrabartty (2005).
* The ability to secrete lipase enzyme of actinomycete strains: was
performed according to the method of Ertuğrul et al., (2007).
* The ability to secrete amylase enzyme of actinomycete strains: was
performed according to the method of Santos (2012).
* The melanin pigment formation of actinomycete strains: was
performed according to the method of Shirling and Gottlieb (1966).
5

- Identification to species of actinomycete strains by molecular
biology method
DNA extraction of actinomycetes was performed according to the
method of Weisburg et al., (1991). The primer pairs were used to amplify
16S-rRNA gene segments of actinomycete strains in the study were: 1492R:
5'-TACGGTTACCTTGTTACGACT-3'
and
27:5'AGAGTTTGATCCTGGCTC-3' (Weisburg et al., 1991). Analytical samples
were sequenced on the ABI 3130XL system. The results were anylized by
using sequecing analysis 6.0 software and compared with the results on the
gene bank to determine the name of actinomycetes.
2.3.5. Content 5: Evaluation of the ability to control rice blast disease
with promising actinomycetes strains under nethouse condition.
- Location: the experiment was carried out at the nethouse of the Plant
Protection Department, Bac Lieu University
- Experimental arrangement: The experiment was arranged in
completely randomized design with 14 treatments (12 treatments using
actinomycetes and 2 controls) with 4 replications.
- Monitoring criteria: count the number of leaf blast lesions according
to Pinnschmidt et al. (1993), measure length and width leaf, and calculate the
percentage of infected leaf area, disease index and disease suppression
efficiency at the time of 4, 6, 8, 10, 12 and 14 days after artificial infection
(DAAI).
2.3.6 Content 6: Evaluation of the ability to control rice blast disease
with promising actinomycetes strains under the field condition.
Field experiment was carried out in 2 seasons: 2017 season in farmer's
fields in Ninh Thanh Loi commune, Hong Dan District, Bac Lieu province
from September 2017 to December 2017 with an area of 2,200 m2, block
layout completely random, 1 factor, 3 repetitions. The 2018 season was

carried out in Ninh Hoa Commune, Hong Dan District, Bac Lieu province
from October 2018 to January 2019 with an area of 2,700 m2, arranged like
the 2017 province, with 4 repetitions. Each experimental unit has a size of
30 m2 (6 m x 5 m). Experimental units are arranged 0.5 m apart to limit the
interaction when handling actinomycetes. The experimental field is 5 m away
6


from the farmer's field in order to limit the influence of fertilizers and
pesticides of next rice fields. Experimental treatments as Table 3.5.
ò Record disease parameters: Each experimental plot placed five
frames (40x50) cm fixed on two diagonal lines. On each frame, the indicators
of leaf blast disease (27, 34, 41, 48 and 55 days after sowing) and blast
disease were recorded collar blast (67, 74 and 81 days after sowing), then
calculate the following indicators: (1) Disease rate; (2) Disease index; (3):
Reduce disease severity.
ò Record productivity targets
+ The number of panicle /m2: in each experimental plot of 30 m2, count
all panicle in 5 plots to record the criteria (40x50 cm2), from which the
number of panicle/m2 is calculated.
+ The number fill grain/ panicle: randomly select 50 flowers in the target
recording box (40x50 cm2). Count the number fill grain in each panicle, and
then calculate the average number of fill grain for each of the 50 panicles.
+ Actual yield (ton/ha): harvest all rice within a frame of 5m2. Weigh
and measure grain moisture at the time of weighing, then convert to 14%
moisture. From there calculate the actual yield.
Table 3.5. Treatments used in the experiment (Days after treatment: DAT)
Treatment
Handling
Processing

Dosage/
Treatment (T)
agent
measures
time
density
Seed coating,
Actinomycetes
S17-MBL -A
NT1
12 GTKS
S17-MBL
suspension:
S17-MBL-A, 20
NT2
20 NSS
108 cfu/ml
Seed coating 40 NSS
S17-MBL-A, 40
NT3
+
S17-MBL-A, 60
NT4
60 NSS
* Seed coating:
Folia
Just enough
S17-MBL-A, 20, 40
NT5
20 & 40 NSS

Spraying
(12 H)
S17-MBL-A, 20, 60
NT6
20
&60
NSS
S17-MBL
S17-MBL-A, 40, 60
NT7
40 & 60 NSS
* Folia
S17-MBL-A,20,40,60
NT8
20, 40 & 60 NSS
Spraying
Coating
+ Tillering
S09-MBL -A, Áo
NT9
12 GTKS
S09-MBL
stage:
S09-MBL-A, 20
NT10
20 NSS
25 lít/1000 m2
Coating +
S09-MBL-A, 40
NT11

40 NSS
+ Flowering
Folia
stage:
S09-MBL-A, 60
NT12
60 NSS
Spraying
40
lít/1000
m2
S09-MBL-A, 20, 40
NT13
20 & 40 NSS
S09-MBL
S09-MBL-A, 20, 60
NT14
20 &60 NSS
S09-MBL-A, 40, 60
NT15
40 & 60 NSS

7


S09-MBL-A,20,40,60

NT16

Fungicide

NT17

Control

NT18

20, 40 & 60 NSS

- Beam
75WP;
- AmistarTop
325SC
Negative
Control

-Tillering
- Flowering

* Fungicide
spraying: as
recommended
by the
manufacturer

Negative
Control

2.4. Data processing

The data were processed by Microsoft Excel program; monitoring
indicators were entered, and data were processed by Excel software.
Statistical calculation of the data by SPSS software; using Duncan's test to
compare the difference at 5% significance level.
Chapter 3: RESULTS AND DISCUSSION
3.1 CONTENT 1: COLLECTED AND ISOLATED THE FUNGUS P.
oryzae, CAUSING RICE BLAST DISSEASE, EVALUATION OF
PATHOGENICITY OF P. oryzae UNDER THE NET HOUSE
CONDITION
3.1.1 Collect disease samples, isolate and identify P. oryzae fungal strains
causing rice blast disease
From October 2015 to December 2015, nine strains of the fungus P. oryzae
causing rice blast disease were collected and isolated in saline-affected rice fields in
four provinces of the Mekong Delta (Ca Mau, Bac Lieu, Kien Giang and Hau Giang).
Disease samples were collected from rice-shrimp fields with an area of over 1,000
m2 and field water with salinity > 0.5‰. The distribution of fungal strains by
sampling location is presented in Table 3.1.

Table 3.1 List of Pyricularia oryzae were collected in saline rice fields in
04 provinces of the Mekong Delta.
No.
1
2
3
4
5
6
7
8
9

Symbols
of strains
Po1-CM
Po2-CM
Po3-BL
Po4-BL
Po5-BL
Po6-HG
Po7-HG
Po8-KG
Po9-KG

Location of collected samples
Khanh Binh –Tran Van Thoi – Ca Mau
Tran Hoi – Tran Van Thoi – Ca Mau
Ninh Hoa – Hong Dan – Bac Lieu
Ninh Quoi A – Hong Dan – Bac Lieu
Ninh Thanh Loi – Hong Dan – Bac Lieu
Hoa Luu –Vi Thanh – Hau Giang
Vinh Vien – Long My – Hau Giang
Tay Yen – An Bien – Kien Giang
Đong Thanh – An Minh – Kien Giang

Note: Po: Pyricularia oryzae

8

Rice seeds
OM5451

OM6976
OM11735
OM5451
OM7347
OM4900
OM5451
OM9921
OM5451


* Symptoms of disease in the field: the disease is like a swallow's
eye with two pointed ends. The middle part is enlarged, around the border is
brown, and the centre is grey-white. The disease on the panicle blast-neck
blast is light brown, causing the rice grain to be flat.
* Morphological characteristics of isolated strains of P. oryzae:
Colonies grow slowly on PDA medium, white when the mycelium is young
and turn black-grey when the mycelium is mature when viewed from the
underside. The disc is black or dark grey in the centre, fades to the edge of
the mushroom, and the mycelium is thin.
* Spore shape and mycelium: Observing the spores under an optical
microscope, the spores are pear-shaped, enlarged at the base and gradually
smaller towards the top, usually with two septa, colourless or pale green.
3.1.2 The ability to cause rice blast disease of P. oryzae strains under net
house conditions
The pathogenicity of nine strains fungus of P. oryzae causing rice blast
disease under net house conditions was shown disease rate (Table 3.2) and
disease index (Table 3.3).
Table 3.2 Rate of rice leaf blast disease area caused by 9 strains of
P.oryzae under nethouse condition over the survey periods.
Fungal

strains
Po1-CM
Po2-CM
Po3-BL
Po4-BL
Po5-BL
Po6-HG
Po7-HG
Po8-KG
Po9-KG
Significance
level
CV (%)

Rate of rice leaf blast disease area (%) over the survey periods
4 DAI
6 DAI
8 DAI
10 DAI
12 DAI
14 DAI
2.11a
1.63ab
1.60ab
0.72cd
0.86cd
1.13bc
0.07d
1.87a
1.15 bc

*
16.5

4,49a
3.12bc
2.45cd
2.32d
2.48cd
3.81ab
1.92d
3.36b
1.91d

7.65a
4.24bc
3.13cd
2.65d
3.06d
5.41b
2.24d
4.95b
2.36d

9.69a
6.98b
4.48cd
3.87cde
4.69c
7.78b
2.87e

6.62b
3.25de

15.36a
7.75c
6.90c
4.25d
6.051c
10.12b
3.74d
11.22b
4.92d

18.42a
8.95d
7.35e
5.12f
6.44e
10.93c
3.95g
15.12b
6.04ef

*

*

*

*

*

10.8

11.4

10.1

8.5

6.7

Note: in the same column numbers followed by the same letters are not statistically significant
in Duncan's test. Data are converted to x + 0,5 for statistical analysis *: statistically
significant difference at 5% level; Days after Inoculation (DAI).

9


The results presented in Table 3.2 and Table 3.3 show that all nine
strains of P. oryzae are capable of causing rice blast disease with typical
symptoms of rice blast disease and exhibiting the potential to cause damage
with various degrees of damage. The difference between disease rates and
disease indexes among fungal strains. Which the Po1-CM strain (collected
in Khanh Binh commune, Tran Van Thoi district, Ca Mau province) showed
the highest pathogenicity through the highest disease rate and highest disease
index out of nine investigated fungal strains. Therefore, strain Po1-CM was
selected as the source of blast fungus for subsequent experiments.
Table 3.3 Index of rice blast disease caused by 9 strains of P.oryzae

under nethouse condition over the survey periods.
Fungal
strains 4 DAI
Po1-CM
5.47a
Po2-CM
6.14a

6 DAI

Disease index (%) over time of survey
8 DAI
10 DAI
12 DAI

14 DAI

11.60abc

15.27a

19.43a

23.47a

24.87a

12.10ab

15.13a

19.17a

20.60ab

20.80b

d

c

cd

Po3-BL

4.80

8.97

Po4-BL

2.00b

10.33bc

Po5-BL

2.14

10.17

11.45

15.40

17.47

18.53bc

Po6-HG

3.37ab

10.96abc

12.57bcd

14.33bc

17.27c

17.93c

Po7-HG

2.63

10.17

12.01

14.53

16.07

17.13c

Po8-KG

4.87a

11.63abc

14.78ab

16.47ab

19.40bc

22.80ab

a

b

b

c

bc

bc

10.06

11.20

15.67

15.73d

11.37cd

12.87bc

13.73d

15.47d

cd

cd

b

bc

c

cd

Po9-KG
4.85
10.25
10.86
13.80
16.46
17.86c
S. level
*
*
*
*
*
*
8.0
7.1
CV (%)
23.8
9.5
9.1
8.7
Note: in the same column numbers followed by the same letters are not statistically significant
in Duncan's test. Data are converted to x + 0,5 for statistical analysis *: statistically
significant difference at 5% level; Days after Inoculation (DAI).
a

bc

d

bc

cd

3.2 CONTENT 2: COLLECT, ISOLATE AND EVALUATE THE
ANTAGONISTIC ABILITY OF ACTINOMYCETE ISOLATES
DERIVED FROM RICE SALINE SOIL AGAINST THE FUNGUS P.
oryzae STRAINS CAUSING RICE BLAST DISEASE UNDER
LABORATORY CONDITION.
3.2.1 Isolation results of actinomycetes
From October 2015 to December 2015, 126 actinomycete strains were
collected and isolated from saline rice fields in 6 provinces of the Mekong
Delta, including Bac Lieu (38 strains), Ca Mau (33 strains), Hau Giang (14
strains), Kien Giang (13 strains), Soc Trang (10 strains), and Tra Vinh (18
10


strains). The distribution of actinomycete strains by sampling location is
presented in Table 3.4.
Observing the growth characteristics of actinomycetes isolated on MS
medium, the colony surface was dry, rough and not as smooth as bacteria.
Most actinomycetes were round radial, with many strains forming concentric
rings (diameter 0.5-10 mm). Actinomycetes can penetrate deeply into the
environment. Actinomycete strains have rich colours such as brown, grey,
white, light yellow, etc. Colour of substrate mycelium, aerial hypha and
pigments diffused on medium as well as colony shape of actinomycetes were
consistent with Waksman's (1961) description of actinomycetes
(Actinomycetes), which could be used to distinguish them from other
microorganisms.

Table 3.4 List of actinomycetes isolated from soils of saline rice fields in 04
provinces of the Mekong Delta.
Total
Symbol
Location
S01-MHG;…;S06-MHG Hoa Luu - Vi Thanh - Hau Giang
6
S07-MHG;…;S14-MHG Vinh Vien - Long My - Hau Giang
8
S01-MKG;…;S06-MKG Tay Yen -An Bien - Kien Giang
6
S07-MKG;…;S13-MKG Đong Thanh - An Minh - Kien Giang
7
S01-MBL;…;S09-MBL
Ninh Thanh Loi - Hong Dan - Bac Lieu
11
S10-MBL ;…;S20-MBL
Ninh Quoi A - Hong Dan - Bac Lieu
15
S21-MBL;…;S29-MBL
Ninh Hoa - Hong Dan - Bac Lieu
12
S01-MCM;…;S11-MCM Khanh Binh -Tran Van Thoi - Ca Mau
11
S12-MCM;…;S19-MCM Tran Hoi - Tran Van Thoi - Ca Mau
8
S20-MCM;…;S24-MCM Khanh An - U Minh - Ca Mau
5
S29-MCM;…;S37-MCM Tran Van Thoi - Tran Van Thoi - Ca Mau
9

S01-MST;…;S10-MST
TT. Tran De - Tran De - Soc Trang
10
S01-MTV;…;S10-MTV
TT. Tra Cu - Tra Cu -Tra Vinh
7
S11-MTV;…;S21-MTV
Tap Son - Tra Cu - Tra Vinh
11
Total
126
3.2.2 Antagonistic ability of actinomycetes against P. oryzae in laboratory
condition

The results of rapid assessment of the antagonistic ability of 126
actinomycete strains isolated with blast fungus (strain Po1-CM) on PDA
medium showed that there were 23 actinomycete strains showing good
antagonism against P. oryzae cause blast disease. Results of evaluation of the
antagonistic ability of 23 promising actinomycete strains through the
parameters of sterility radius (Table 3.5) and antagonistic efficiency (Table
3.6).

11


The results of Table 3.5 and Table 3.6 show that there are 7
actinomycete strains S17-MBL, S31-MCM, S06-MBL, S09-MBL, S03MST, S18-MCM and S09-MTV which are resistant to P. oryzae through a
high sterility ring radius and high antagonistic performance up to 9 days after
experimental setup. In which, three strains S17-MBL, S09-MBL and S06MBL showed the highest antagonistic ability.
Table 3.5 Antagonistic ability of 23 actinomycetes against P. oryzae over the

survey times.
Radiuses of inhibition zones over times (mm)
Treatment
3 DAT
5 DAT
7 DAT
9 DAT
ab
b
e
S03-MST
16.3
12.0
8.0
6.2de
fg
fg
fg
S04-MST
12.4
7.8
5.6
4.1 h
gh
g
g
S01-MTV
11.8
7.2
5.2

4.0h
def
def
fg
S07-MTV
13.6
8.4
5.6
2.5j
bc
b
d
S09-MTV
15.3
12.0
9.0
7.8c
S14-MHG
13.4ef
7.8fg
6.2fg
4.4gh
fg
h
fg
S05-MKG
13.0
6.3
5.4
3.8hi

fg
c
e
S10-MKG
12.8
9.6
7.6
5.0fg
hi
i
i
S12-MKG
11.0
4.2
2.2
0.0l
fg
cde
e
S05-MBL
12.4
8.8
7.5
5.8e
abc
b
d
S06-MBL
15.5
12.2

9.2
8.6b
S09-MBL
14.7cd
11.6b
9.4cd
8.4b
fg
def
fg
S14-MBL
12.4
85
5.8
3.0j
a
a
a
S17-MBL
16.6
15.3
13.8
12.8a
S05-MCM
10.6 i
82def
5.8fg
4.0h
fg
c

f
S06-MCM
13.0
9.5
6.4
3.2ij
S11-MCM
14.7cd
11.8b
8.4de
5.0fg
fg
efg
h
S12-MCM
12.8
8.0
3.8
1.2k
fg
fg
h
S14-MCM
13.0
7.8
4.2
0.8k
S18-MCM
15.2bc
12.2b

10.2bc
6.6d
c
b
d
S23-MCM
10
11.7
9.2
5.6ef
S27-MCM
14.4cde
9.1cd
5.7fg
0.8k
c
b
b
S31-MCM
15.0
12.4
10.6
7.8c
Significance level
*
*
*
*
CV (%)
6.62

6.81
10.21
12.03
Note: in the same column numbers followed by the same letters are not statistically significant
in Duncan's test. *: statistically significant difference at 5% level; Days after Testing (DAT).

12


Table 3.6 Antagonist efficacy (%) of 23 actinomycetes with P. oryzae
over the survey times
Treatment
S03-MST
S04-MST
S01-MTV
S07-MTV
S09-MTV
S05-MKG
S10-MKG
S12-MKG
S14-MHG
S05-MBL
S06-MBL
S09-MBL
S14-MBL
S17-MBL
S05-MCM
S06-MCM
S11-MCM
S12-MCM

S14-MCM
S18-MCM
S23-MCM
S27-MCM
S31-MCM
Significancel evel
CV (%)

Antagonist efficacy over times (%)
3 DAT
5 DAT
7 DAT
41.43a
52.73b
51.85bc
fgh
ghi
7.14
22.73
31.11g
gh
ghi
7.14
22.73
34.07fg
de
g
14.29
25.91
29.63g

ab
b
37.14
52.73
53.33b
5.71gh
15.91 j
30.37g
d
ef
18.57
37.73
43.70de
hi
k
4.29
10.91
17.78i
efg
gh
10.00
23.64
31.85g
ghi
gh
7.43
24.55
34.81fg
ab
bc

31.43
48.64
51.85bc
ab
cd
39.29
46.36
50.37bc
20.00cd
35.91f
41.85de
40.71a
59.09a
60.74a
ij
f
4.00
33.18
41.48de
def
f
12.86
34.55
39.26ef
ab
cd
28.57
45.45
45.93cd
efg

j
8.57
17.27
22.96h
hi
ij
4.27
18.18
22.22hi
ab
bc
35.71
50.00
54.81b
28.57bc
42.27de
46.67cd
10.00efg
19.55hij
20.74hi
ab
ab
38.57
53.64
60.74a
*
*
*
20.59
7.76

5.92

9 DAT
60,44b
43,96h
47,80fgh
39,01i
59,34bc
46,70fgh
55,49cd
34,07j
45,60gh
50,00efg
62,09b
66,48a
50,82ef
68,68a
53,85de
50,55ef
49,45fg
37,91i
36,26ij
60,44b
59,34bc
32,97j
60,99 b
*
3.84

Note: in the same column numbers followed by the same letters are not statistically significant

in Duncan's test. Data are converted to x for statistical analysis *: statistically significant
difference at 5% level; Days after Testing (DAT).

3.2.3 The antagonistic ability of seven actinomycete strains against P.
oryzae under the conditions of addition of NaCl 2‰
The results of radiuses of inhibition zones and antagonist efficacy of
seven actinomycetes tested on the medium supplemented with NaCl 2‰ salt
over the survey times differed from those in the experiment on the medium
without NaCl salt. The results are presented in Tables 3.7 and Table 3.8.
Among the seven actinomycetes strains tested, four actinomycetes (S06MBL, S09-MBL, S17-MBL and S18-MCM) had the highest radiuses of
inhibition zones and antagonist efficacy at the time of nine DAT; There were
13


three actinomycetes strains (S06-MBL, S09-MBL and S17-MBL) with the
highest radiuses of inhibition zones and antagonist efficacy at 11 DAT.
Table 3.7 Antagonistic ability (%) of actinomycetes against P. oryzae in
laboratory condition (added NaCl 2‰) over the survey times.
Treatment
S06-MBL
S09-MBL
S17-MBL
S09-MTV
S03-MST
S18-MCM
S31-MCM
Significance level
CV (%)

Radiuses of inhibition zones over times (mm)

3 DAT 5 DAT
7 DAT
9 DAT 11 DAT
a
a
a
18.0
17.0
15.6
13.4a
12.2a
17.2ab
15.8ab
14.8a
13.6a
12.0a
17.2ab
15.8ab
14.6a
13.6a
12.3a
abc
b
b
b
16.4
11.8
6.2
6.0
2.6c

bc
bc
bc
c
15.4
9.6
4.6
1.8
1.6c
ab
ab
ab
a
17.4
15.0
13.8
12.0
9.4b
c
c
c
c
15.0
8.2
2.8
1.6
1.6c
*
*
*

*
*
7.79
10.03
14.25
15.03
17.76

Note: in the same column numbers followed by the same letters are not statistically significant
in Duncan's test. *: statistically significant difference at 5% level; Days after Testing (DAT)

Table 3.8 Antagonist efficacy (%) of actinomycetes with P. oryzae in
laboratory condition (added NaCl 2‰) over the survey times.
Treatment
S06-MBL
S09-MBL
S17-MBL
S09-MTV
S03-MST
S18-MCM
S31-MCM
Significance level

CV (%)

3 DAT
46.15a
36.59ab
36.59ab
29.27b

31.71b
35.34b
9.76c
*
14.60

Antagonist efficacy over times (%)
5 DAT
7 DAT
9 DAT
63.75a
73.04a
75.84a
62.50a
73.04a
76.51a
a
a
62.50
69.57
75.17a
47.50b
40.00b
53.69b
c
c
36.25
31.30
43.62c
60.75a

72.17a
76.51a
d
d
16.25
22.61
38.26d
*
*
*
6.39
4.91
3.64

11 DAT
78.50a
78.51a
78.57a
56.59b
54.95b
76.35a
49.45c
*
3.49

Note: in the same column numbers followed by the same letters are not statistically significant
in Duncan's test. Data are converted to arcsin x for statistical analysis *: statistically
significant difference at 5% level; Days after Testing (DAT).

Thus, the experimental results in Table 3.7 and Table 3.8 show that

actinomycete strains exhibit different antagonisms against P.oryzae under the
addition of NaCl (2g/l) compared with the conditions without NaCl. In which
strain S06-MBL always showed more potent antagonism against P. oryzae than
strain S31-MCM, the difference was statistically significant at a 5% significance
level (Figure 3.6)

14


S17MBL

S18-MCM

S09-MTV

S09-MBL

S31MCM

S06MBL

ĐC

Figure 3.6. Resistance against P. oryzae fungi of actinomycetes in the medium
supplemented with NaCl 2‰ at 11 DAT.

3.2.4. The ability to inhibit the growth of P. oryzae fungal spores of promising
actinomycetes
The results of the inhibition of P. oryzae spore germination of the
experimental actinomycetes are presented in Table 3.9. The results showed that all

seven experimental actinomycetes strains showed the ability to inhibit the growth of
P. oryzae fungus to different extents. Strain S17-MBL showed high inhibition of
fungal spore germination with a low spore germination rate from 6 hours after the
experiment until 24 hours after the experimental setup.
Table 3.9 Rate of spore of P. oryzae sprouted over the survey time points (%).
Treatment
Rate of sporulation over times of survey (%)
6 HAT
12 HAT
24 HAT
S06-MBL
5.14d
17.6c
20.1cd
cd
c
S09-MBL
6.94
16.4
17.5d
e
c
S17-MBL
0.00
14.2
15.9d
S09-MTV
9.31b
24.5b
27.4b

S03-MST
8.61bc
18.6bc
24.3bc
bc
bc
S18-MCM
8.61
18.6
25.8b
d
c
S31-MCM
6.11
16.1
17.6d
a
a
Control
14.4
31.5
35.4a
Significance level
*
*
*
CV (%)
27.8
12.1
9.6

Note: in the same column numbers followed by the same letters are not statistically significant in Duncan's
test. Data 6 HAT converted to x + 0,5 , 12 và 24 HAT converted to arcsin x for statistical analysis.*:
statistically significant difference at 5% level; Hours after Testing (HAT)

15


Over the survey, it was found that the treatments with four actinomycete
strains, S06-MBL, S09-MBL, S17-MBL and S31-MCM, maintained a stable low
germination rate, demonstrating the ability to inhibit P. oryzae better than the rest of
the strains. However, strain S06-MBL has BKVVK and higher antagonistic
efficiency than strain S31-MCM when tested in the saline environment (NaCl 2g/l).
Thus, three actinomycete strains, S06-MBL, S09-MBL and S17-MBL, were selected
for the follow-up experiments.
3.3 CONTENT 3: INVESTIGATE A NUMBER OF MECHANISMS
RELATED TO THE ANTAGONISTIC ABILITY OF PROMISING
ACTINOMYCETES
3.3.1 The ability to secrete chitinase enzyme to degrade chitin of 3 actinomycetes
under laboratory condition.
The ability to secrete chitinase enzymes to break down chitin is shown by the
chitin lyse halo radius (Table 3.10) and the amount of chitinase enzyme secreted by
actinomycetes was presented in Table 3.11
Table 3.10 Chitin lyse halo radius (mm) of the actinomycetes tested over survey
times.
No.
Actinomycetes
Chitin lyse halo radius (mm)
strain
1 NSTN 3NSTN
5NSTN

7NSTN
1
S06-MBL
4.2b
101c
15.3b
18.5b
2
S09-MBL
5.2a
13.5a
18.9a
23.3a
a
b
a
3
S17-MBL
5.1
12.8
18.3
23.2a
Significance level
*
*
*
*
CV (%)
6.22%
5.57%

5.3%
4.26%
Note: in the same column numbers followed by the same letters are not statistically significant
in Duncan's test. *: statistically significant difference at 5% level; Days after Testing (DAT)

Bảng 3.11 Concentration of chitinase (IU/ml) of 03 actinomycetes over survey
times.
Concentration of chitinase (IU/ml)
Actinomycetes
No.
strain
1 NSTN
3NSTN
5NSTN
7NSTN
1
S06-MBL
0.15c
0.20c
0.26b
0.28c
2
S09-MBL
0.27a
0.38a
0.44a
0.51a
bc
b
b

3
S17-MBL
0.18
0.27
0.29
0.33b
Significance level
*
*
*
*
CV (%)
5.81
6.43
6.95
5.36
Note: in the same column numbers followed by the same letters are not statistically significant
in Duncan's test. *: statistically significant difference at 5% level; Days after shaking (DAS).

16


The results of Table 3.10 and Table 3.11 show that all 3 tested
actinomycete strains have the ability to secrete chitinase enzymes, in which
2 strains S09-MBL and S17-MBL had the highest ability to secrete chitinase
enzyme with the highest radiuses of inhibition zones and enzyme content
secretion was highest until 7 days after the testing.
3.3.2 The ability to secrete β-1,3-glucanase enzyme to degrade β-1,3glucan of 03 actinomycetes strains under laboratory condition.
The ability to secrete β-glucanase enzyme to break down β-glucan was
shown by the radiuses of inhibition zones (Table 3.12) and the content of βglucanase enzyme secreted by actinomycetes was presented in Table 3.13.

Table 3.12 Radiuses of inhibition zones β-1,3-glucan (mm) of the tested
actinomycetes over the survey times.
Radiuses of inhibition zones β-1,3-glucan
No.
Treatment
(mm)
10 NSTN
12 NSTN
14 NSTN
b
b
1
S06-MBL
9.6
10.6
11.6c
c
a
2
S09-MBL
9.0
12.2
12,8bc
3
S17-MBL
9.8a
12.0ab
14,0a
Significance level
*

*
*
CV (%)
6.03
4.12
4.8
Note: in the same column numbers followed by the same letters are not statistically significant
in Duncan's test. *: statistically significant difference at 5% level; Days after Testing (DAT)

Table 3.13 Concentration of β-1,3-glucanase (IU/ml) of 03 actinomycetes over
survey times.
Concentration (IU/ml) of β-glucanase over survey time
10 NSTN
12 NSTN
14 NSTN
b
bc
1
S06-MBL
0.28
0.21
0.07b
c
c
2
S09-MBL
0.21
0.18
0.05b
a

a
3
S17-MBL
0.46
0.47
0.15a
Significance level
*
*
*
CV (%)
6.70
13.76
7.50
Note: in the same column numbers followed by the same letters are not statistically significant
in Duncan's test. *: statistically significant difference at 5% level; Days after shaking (DAS).
No.

Treatment

The results showed that all 3 experimental actinomycete strains were
able to secrete β-1,3-glucanase to degrade β-glucan, in which strain S17MBL showed the highest ability to secrete β-1,3-glucanase enzyme with the
17


highest radiuses of inhibition zones and the highest secreted enzyme content
was 14 days after testing.
3.4 CONTENT 4: IDENTIFY PROMISING ACTINOMYCETES
SPECIES BY OBSERVATION BIOLOGICAL CHARACTERISTICS
METHODS AND MOLECULAR BIOLOGY METHODS.

3.4.1 Identification of actinomycetes based on culture, morphological
and biochemical characteristics
The survey results on the culture characteristics, morphological
characteristics and biochemical characteristics of the three experimental
actinomycetes are presented in Table 3.14, Table 3.15 and Table 3.16.
Table 3.14 Morphological and biochemical characteristics of 3
experimental actinomycetes strains.
Characteristics
Chain of spores
Spore stem
Spore surface
Color of aerial
hypha
Color
Melanin pigment
Salt tolerance
Enzym secrection

Gram

Experimental actinomycetes strains
S06-MBL
S09-MBL
S17-MBL
Straight
Straight
Hook
Flexous
Straight -Flexous Straight -Flexous
Sleek

Sleek
Sleek
White
White
Grey
No
No
≤ 6%
Protease,
Amylase, Lipase,
Cellulase
Positive

No
Yellow-brown
≤ 8%
Protease,
Amylase, Lipase,
Cellulase
Positive

No
No
≤ 8%
Protease,
Amylase,
Lipase,
Cellulase
Positive

Figure 3.10 Shape of straight spore stem (A; S17-MBL), hook spore chain (A, S17MBL), straight chain of spore (B; S09-MBL), spore surface smooth (C; S17-MBL).

18


Table 3.15 The secretion of amylase, protease and lipase enzymes of
actinomycetes
Radius of substrate resolution zone (mm) of 3
actinomycete strains at 7 days after experiment (*)
Amylase
Protease
Lipase
9,5 ± 1,29
8,3 ± 0,50
10,8 ± 0,63
10,8 ± 1,16
11,5 ± 0,57
11,2 ± 0,65
8,8 ± 0,96
13,5 ± 0,58
9,8 ± 0,96

Actinomycetes
strain
S06-MBL
S09-MBL
S17-MBL

(*) Number is average of three times repeat ± SD

Bảng 3.16 Salt tolerance test of 3 actinomycete strains.
Actinomycetes
strain

The concentration of salt NaCl (%)
0

3

4

5

6

7

8

9

S06-MBL
S09-MBL
S17-MBL

+++
+++
+++

+++

+++
+++

+++
+++
+++

++
++
++

++
++
++

++
+

++
+

-

Note: (+++) Good; (++) Modrerate; (+) Poor ; (−) No growth.

Morphological characteristics (Spore stem, chain of spores, spore
surface), biochemical characteristics (color, melanin pigment, enzyme, gram
secretion and salt tolerance ability) of the 3 actinomycete strains S06-MBL,
S09-MBL, S17-MBL are presented in Table 3.14, Table 3.15, Table 3.16 and
compared with the key actinomycetes of the International Streptomyce

Project (Shirling and Gottlieb, 1972; Pridham et al., 1958 ; Waksman, 1961)
showed that these three actinomycetes were classified in the genus
Streptomyces.
3.4.2 Identification of actinomycetes by molecular biology method
Based on the results of Table 3.20, it shows that the 3 strains of
actinomycetes tested have similarity from 98 to 100% when compared with
the standard species based on the 16S - rRNA gene sequence. Specifically,
strain S06-MBL has 99% similarity with Streptomyces fradiae species; strain
S09-MBL has 99% similarity with Streptomyces bikiniensis species and
strain S17-MBL has 98% similarity with Streptomyces lavendulae species.

19


Hình 3.13 Sản phẩm PCR được
khuếch đại với cặp mồi thuộc vùng
16S-rRNA của 3 chủng xạ khuẩn
S06-MBL, S09-MBL và S17MBL.

Table 3.20 Results of identification of 3 actinomycetes based on 16S-rDNA
region sequences
Base pair (bp)
Sample
S06-MBL
S09-MBL
S17-MBL

1462

Degree of

similarity
(%)
99

Code of the same
strain coin on
GenBank
AB184253.1

1476

99

NR_112436.1

1515

98

DQ645958.1

Species
Streptomyces
fradiae
Streptomyces
bikiniensis
Streptomyces
lavendulae

3.5 CONTENT 5: EVALUATION OF THE ABILITY TO CONTROL RICE

BLAST DISEASE WITH PROMISING ACTINOMYCETES STRAINS
UNDER NETHOUSE CONDITION.

The ability to control rice blast disease caused by P. oryzae of
actinomycete strains under net house conditions is shown by disease rate
(Table 3.21), disease index (Table 3.22) and reduced disease severity (Table
3.23).

Results Table 3.21, Table 3.22 and Table 3.23 show the treatment of
actinomycete strains (S06-MBL, S09-MBL and S17-MBL) when combined
treatment at 2 days before and 2 days after artificial inoculation has low
disease rate, low disease index and the highest disease reduction effect lasts
up to 14 days after artificial infection.
Table 3.21 Rate of rice leaf blast disease area (%) of actinomycetes strains
under net house condition over the survey periods.
Rate of rice leaf blast disease area (%) over the survey periods
Treatment
4DAI 6 DAI
8 DAI
10 DAI 12 DAI 14 DAI
a
cd
b
S06-MBL-A
4.51
7.63
6.98
6.12b
5.41c
7.02b

c
def
b
d
bc
S06-MBL-A-T
2.04
6.88
6.87
4.62
5.17
5.84cd
S06-MBL-A-S
1.98c
8.89b
6.06cd
5.88bc
5.16bc
5.88cd
c
def
de
d
de
S06-MBL-A-TS
2.19
6.49
5.49
4.54
4.67

5.16e
S09-MBL-A
3.13b 7.02de
6.16c
5.89bc
5.32c
6.24c

20


S09-MBL-A-T
S09-MBL-A-S
S09-MBL-A-TS
S17-MBL-A
S17-MBL-A-T
S17-MBL-A-S
S17-MBL-A-TS
Beam 75WP
Control
Significance level
CV(%)

2.12c
2.12c
1.14d
2.45bc
1.96c
2.15c
1.28d

0.64e
4.80a
**
10.73

6.09ef
6.06f
2.52gh
7.26de
6.50def
6.60def
3.16g
1.43i
9.98a
**
6.70

5.13e
5.12e
4.21f
7.42b
5.85cd
5.18e
4.57f
4.29f
9.52a
**
3.36

4.84d

4.59d
2.86f
6.22b
5.75bc
5.48c
4.08e
2.35g
12.08a
**
3.28

4.61de
4.25e
3.33f
6.95b
4.81bcd
4.88bcd
4.22e
3.48f
12.69a
**
3.62

5.29de
4.25f
2.88h
6.53bc
6.14c
5.90cd
3.48g

3.04h
11.09a
**
3.62

Note: in the same column numbers followed by the same letters are not statistically significant in Duncan's
test. Data are converted to x + 0,5 for statistical analysis *: statistically significant difference at 5%
level; Days after Inoculation (DAI).

Table 3.22 Index of rice blast disease of actinomycetes strains under net house
condition over the survey periods.
Disease index (%) over time of survey
Treatment
4 DAI
6 DAI
8 DAI
10 DAI
12 DAI 14 DAI
a
c
cd
b
S06-MBL-A
13.08 22.63
20.38
20.19
18.11c
24.82b
S06-MBL-A-T
5.92c

18.14e
21.06c
17.24cde
17.56cde 20.45cde
c
b
def
bc
S06-MBL-A-S
5.74
26.67
18.77
19.41
17.29cde 20.57cd
S06-MBL-A-TS 6.35c
19.45 ef
17.02fg
14.98efg
15.64def 18.06e
b
cde
de
bc
S09-MBL-A
8.81
21.07
19.11
19.44
17.81cd
21.84c

c
cd
gh
def
e
S09-MBL-A-T
6.15
22.28
15.89
15.96
15.43
18.53de
S09-MBL-A-S
5.74c
18.17f
15.87gh
15.14efg
14.23f
14.89f
e
h
i
i
g
S09-MBL-A-TS 3.31
7.57
13.05
9.3h
11.17
10.08i

S17-MBL-A
7.12bc 21.29cde
23.01b
20.52b
23.29b
22.85bc
cd
ef
efg
bc
de
S17-MBL-A-T
5.17
19.49
18.13
18.97
16.10
21.51c
S17-MBL-A-S
6.21c
19.80def
16.07gh
18.08bcd 16.34de
20.67cd
de
g
h
fg
f
S17-MBL-A-TS 3.70

11.99
14.18
13.46
14.14
12.18gh
Beam 75WP
1.86f
4.30i
13.31i
7.74i
11.61g
10.63hi
a
a
a
a
a
Control
14.37
32.88
33.31
37.72
39.04
39.36a
Significance level
**
**
**
**
**

**
CV%
11,04
4,73
4,70
5,53
4,30
4,39
Note: in the same column numbers followed by the same letters are not statistically significant
in Duncan's test. Data 4 DAI are converted to x + 0,5 , other datas are converted to arcsin
x for statistical analysis *: statistically significant difference at 5% level; Days after
Inoculation (DAI).

21


Table 3.23 Reduce disease severity (%) of actinomycetes under net house
condition over the survey periods.
Antagonistic efficacy (%) over time of survey
Treatment
4 DAI
6 DAI
8 DAI
10 DAI
12 DAI
14 DAI
f
g
fg
g

e
S06-MBL-A
261
28.89
30.57
48.08
55.01
35.87e
d
d
gh
fg
de
S06-MBL-A-T
55.87
43.00
28.29
55.68
56.36
47.18cd
S06-MBL-A-S
57.26d
16.20h 36.06def
50.11gh
57.04de
46.84cd
d
ef
cde
cd

cd
S06-MBL-A-TS
52.70
38.80
42.05
61.49
61.15
53.34c
e
efg
efg
gh
de
S09-MBL-A
34.40
33.78
34.92
50.02
55.74
43.55d
d
fg
bc
ef
cd
S09-MBL-A-T
54.16
30.00
45.88
58.98

61.66
52.12c
S09-MBL-A-S
54.58d
42.92d
45.96bc
61.08def
64.37bc
61.53b
b
b
a
ab
a
S09-MBL-A-TS
75.33
76.23
55.52
75.76
72.25
73.94a
de
efg
i
h
f
S17-MBL-A
46.99
33.10
21.64

47.25
42.13
40.97de
S17-MBL-A-T
61.49cd
38.75ef 38.26def
51.22gh
60.00cde
44.43d
d
ef
bc
fgh
cde
S17-MBL-A-S
53.76
37.77
45.26
53.50
59.40
46.60cd
bc
c
ab
bc
bc
S17-MBL-A-TS
72.48
62.31
51.72

65.40
64.85
68.53ab
a
a
a
a
ab
Beam 75WP
88.71
86.29
54.21
80.44
68.79
71.72a
Significance level
**
**
**
**
**
**
CV%
11.69
7.05
8.82
6.19
3.52
5.39
Note: in the same column numbers followed by the same letters are not statistically significant

in Duncan's test. Data are converted to arcsin x for statistical analysis *: statistically
significant difference at 5% level; Days after Inoculation (DAI).

3.6 CONTENT 6: EVALUATION OF THE ABILITY TO CONTROL
RICE BLAST DISEASE WITH PROMISING ACTINOMYCETES
STRAINS UNDER THE FIELD CONDITION ON 2017 AND 2018
SEASONS.
3.6.1 Height and number of shoots of experimental rice
The results of field experiments in saline fields showed that the
treatment of seed coat and spraying actinomycetes suspension on leaves did
not affect the growth of height and number of shoots of rice plants in the
experimental field in both seasons.
3.6.2 The ability to control leaf blast disease
3.6.2.1 Rate of leaf blast disease
Experimental results showed that both actinomycetes strain S09-MBL
and S17-MBL managed blast disease caused by P. oryzae. The disease was
lower than the control treatment in the 2017 and 2018 seasons. On the other
22