The thesis defense seminar on August 16, 2018, focused on screening local, improved, and hybrid rice genotypes against blast disease (Pyricularia oryzae) in Surkhet and Banke, Nepal. The research aimed to identify resistant rice varieties and understand the variations in disease reactions across locations, leading to findings that included 28 resistant and 15 moderately resistant genotypes. The results indicated a diverse range of genetic responses, emphasizing the need for host resistance in managing blast disease in rice cultivation.

1. M.S. Thesis Defense Seminar
August 16
August 16th
th
, 2018
, 2018

2. SCREENING OF LOCAL, IMPROVED AND
HYBRID RICE GENOTYPES AGAINST BLAST
DISEASE (Pyricularia oryzae) IN SURKHET
AND BANKE CONDITIONS

3. Prof. Sundar Man Shrestha, Ph.D.
Head
Department of Plant Pathology
Chairman, advisory committee
Adjunct Prof. Hirakaji Manandhar, Ph.D.
Department of Plant Pathology
Member, advisory committee
Bedananda Chaudhary, Ph.D.
Senior Scientist
Member, advisory committee
ADVISORY COMMITTEE

4. OVERVIEW OF THE PRESENTATION
 INTRODUCTION
 OBJECTIVES
 LITERATURE REVIEW
 MATERIALS AND METHODS
 RESULTS AND DISCUSSION
 SUMMARY AND CONCLUSION

5.  Area of Rice cultivation:159.8 million ha
 Total production: 740.9 million tons
(FAO STAT, 2018).
 First most important cereal crop of Nepal
 Area of cultivation: 15,52,469 ha
Total production: 52,30,327 mt and
Productivity: 3.3 mt/ha (MoAD 2016)
Contributions:
 21% in the AGDP
 10% to GDP
(MoF, 2017)
INTRODUCTION

6. INTRODUCTION cont…..
• About 90% of the rice grown in the world is produced and
consumed in Asian region (Singh, 2004)
• Rice is grown over a wide range of agro-ecological conditions
from 60 m asl to 3050 m asl in Nepal (Yadaw et al., 2007).
• Rice blast Pyricularia oryzae anamorph (Rossman et al., 1990)
Magnaporthe oryzae Telomorph (Valent et.al 1986) is major
constraints of rice production (Chaudhary, 2015)
• In Nepal rice blast first reported in 1966 (Manandhar 1987,
Chaudhary, 1999) and locally known as “Maruwa Rog”.
• Divided into leaf and panicle pathosystem (Teng, et al.,1991).

7. INTRODUCTION cont…..
• Blast is the most devastating disease (Singh et.al., 2015) with
wide geographic distribution (IRRI 2013, Vasudevan et al.,
2014, Singh et al., 2015)
• Several rice blast epidemics have occurred in different parts
of the world, resulting loss of 50 to 90 % (Jamal et.al, 2012)
• In Nepal 10-80% yield reduction was reported in severe
cases (Manandhar et al., 1992)
• It Infects all plant parts, including the roots (Duan et al.,
2014), leaves shows diamond shaped lesions with white grey
center and dark brown margin and neck is blackened.

8. INTRODUCTION cont…..
• Blast pathogen is highly variable for genetic adaptation to cause
the disease on newly released popular varieties (Chaudhary, et al.,
2004)
• In Nepal the disease is also distributed throughout the rice growing
areas from subtropical to temperate regions (Shahi and Heu, 1979;
Chaudhary et al., 1994; Shrestha, 1994)
• Host resistance is convenient, preferable cost effective, safe and
practical means of disease management (Sharma, 1995)
• About 2000 different landraces of rice exist in Nepal (Gupta et al.,
1996) and these are disease and stresses well resisted (Joshi, Brar,
Pannu and Paramjit, 2007)
8

9. INTRODUCTION cont…..
• The disease causes complete seedling loss of susceptible
rice cultivars in the dry seed bed nursery (Chaudhary,
1994)
• A relative humidity of 95% and an average temperature of
26-27°C favor blast infection (Munoz, 2008)
• Leaf blast in upland rice reaches maximum disease severity
at 25 to 40 days after seeding

10. OBJECTIVES
 To identify resistant local, improved and hybrid rice
genotypes against blast disease under natural epiphytotic
field conditions.
 To determine variations in blast disease reactions of rice
genotypes between locations.

11.  Host plant: Rice
 Nomenclature, morphology and taxonomy of the pathogen
 Host range and variability
 Occurrence and distribution
 Relation between leaf and neck blast
 Overview of blast resistant genes
 Economic importance
 Disease symptoms
 Disease cycle and disease development
 Infection and sporulation
 Dispersal Predisposing factors
 Integrated management of blast disease of rice
LITERATURE REVIEW

12. MATERIALS AND METHODS
 Plant materials
Composed of three sets, 70 Local genotypes from Genebank,
Khumaltar, 20 improved genotypes from NRRP, Hardinath and 8
Hybrid rice genotypes from Agri Nepal, Tulsipur
 Planting
 Test plots under both Khajura Dashrathpur conditions were sown
on Shrawan, 2073 .
 Experimental design
Randomized complete block design with two replications
 Research site
Experiment was conducted in the field of RARS, Khajura (181
masl) and ARS, Surkhet, (580 masl) Nepal during 2016

13. Research site
Research site
Research site at ARS, Surkhet and RARS, Banke
Research site at ARS, Surkhet and RARS, Banke

14. Treatment detail
Treatment detail

19. MATERIALS AND METHODS cont….
• A total of 101 rice genotypes including checks (resistant
and susceptible) were screened in upland nursery condition
having the individual plot size of 500 cm2
.
• Susceptible and resistant checks were planted after every 10
test entries to check uniformity of infection.
• The cultivar Masuli and Shankharika were taken as
susceptible check and Sabitri as a resistant check in the field

20. MATERIALS AND METHODS cont….
• The mixtures of several susceptible cultivars (Mansuli,
Shankharika and Jumli marshi) were planted in inoculum
plot and spreader rows to ensure presence of inoculum
consisting of diverse races of the blast pathogen
• To create a blast congenial environment the screening
nursery was designed as per international specifications as
described by Jennings et al., 1979, Thapa and Manandhar,
1985

21. Wind break plot
Dhaincha was planted (15.6 m x 1.25 m) 30 days
prior to seeding of first two inoculum row
Inoculum plot
(Shankharika, Mansuli and Jumli marshi) (12.1 m
x 1.25 m), in four different dates at a week interval
Spreader rows
2 and 3 lines spaced 10 cm apart from each other
Test plot
Two test plots at 30 cm gap (12.1 m x 1.25 m), 5 gm seed
of each genotype was seeded continuously in a single row
of 50 cm length with a spacing of 10 cm between entries.
50 cm
50 cm

22. Layout of the field experimental plot
Layout of the field experimental plot
15.6 m
15.6 m
50 cm
50 cm
50 cm
50 cm
Inoculum Plot
Inoculum Plot
Test Plot
Test Plot
Test Plot
Test Plot
Inoculum Plot
Inoculum Plot
Wind break plot
Wind break plot

23. Layout of the field experimental plot
Layout of the field experimental plot
Wind break plot
Wind break plot
Inoculum plot
Inoculum plot
T
e
s
t
p
l
o
t
T
e
s
t
p
l
o
t
50 cm
Spreader Row

24. Weather conditions recorded at Dasharathpur, Surkhet
24

25. Weather conditions recorded at Khajura, Banke
25

26. Field preparation
• Land preparation was done during the first week of July
• Soil was made pulverized and levelled with the help of spade, hoe,
and rake before sowing, debris were removed
• The final layout of the experiment was done during the time of
dhaincha sowing.
• Farm yard manure @10 t/ha, was mixed into soil two weeks before
dhaincha sowing, and chemical fertilizers were applied @120:40:0
kg
• Irrigation was done at weekly interval.
• Manual weeding was done two times at 25 DAS and 35 DAS

27. Disease assessment
 Disease scoring was done beginning from
the 20th
days of sowing by using the disease
rating scale 0-9 as described by IRRI (2002)
and Ghazanfar et al (2009)
 Subsequent four observations were taken at five days interval

29. Materials and Methods cont….
Disease Assessment
 Disease severity % was calculated per plot by using the following
formula:
Leaf blast severity (%) = score recorded * 100
9
 Estimation of Area under disease progress curve AUDPC was
calculated by using the following formula (Das et al., 1992)
Where,
• Yi= Disease scored on ith
first date
• Ti= Date on which the disease was scored
• n = Number of dates on which disease was scored.
)
(
5
.
0
)
(
AUDPC 1
1
i
1 i
i
n
i
i T
T
Y
Y 

 




30. Materials and Methods cont….
Collection of leaf samples and isolation of pathogen
•Diseased leaves were cut into 2 to 3 cm and surface sterilized
with 1% NaoCl for 1 minute and rinsed 3 times with distilled
water.
•Transferred to sterilized glass petri-plates containing two
layers of moist blotting paper and incubated in an incubator at
25±1ºC for 24 hours to get sporulation and observed under
compound microscope for confirmation

31. Categories of rice genotypes based on mean AUDPC value
Categories of rice genotypes based on mean AUDPC value

32.  Recorded data were tabulated treatment wise under two
replications.
 Processed to fit into R-studio software and analysis was
conducted using R 3.4.1 (R Core Team, 2017), and Microsoft
excel program for data tabulation and by using Duncan’s
Multiple Rage Test (DMRT) at 5 % level of significance.
STATISTICAL DATA ANALYSIS

33. RESULTS AND DISCUSSION

35. In cluster 1st
35.64 % of genotypes were grouped as
resistant and in cluster 2nd
33.66 % of the genotypes
were grouped as moderately resistant, in cluster 3rd
9.90 % of the total genotypes were grouped as
moderately susceptible, in cluster 4th
3.97 % of the
total genotypes where grouped as susceptible and in
cluster 5th
17.82 % of the total genotypes were
grouped as highly susceptible

36. 69.61
79.74
89.87
100.00
Genotypes
Similarity
Area Under Disease Progress Curve at Khajura,Banke,2016/17
Cluster-I
Cluster-II Cluster-III
Cluster-IV
Cluster-V

37. • In 1st
cluster 27.72 % of the total genotypes were
grouped as resistant, in cluster 2nd
14.85 % of the
total genotypes were grouped as moderately
resistant, in cluster 3rd
15.84 % of the total
genotypes were grouped as moderately
susceptible, in cluster 4th
38.61 % of the total
genotypes were grouped as susceptible where as
in cluster 5th
2.97 % of the total genotypes were
grouped as highly susceptible.

39. • Khanal et al. (2016) also reported Hardinath-1, Radha-11,
Makwanpur-1, Ramdhan as moderately resistant to rice blast
disease.
• Rijal et al. (2017) also found Sabitri as resistant and Black rice,
Shankharika as highly susceptible, however contrast result was
reported as Hardinath -1 was highly susceptible to rice blast in
Chitwan condition.
• Tarahara-1, Hardinath-2 were found resistant, simlilar results were
also reported by Dangal et al., 2013.

41. • Most of the screened hybrid rice revealed resistant
reaction to leaf blast disease, however Garima 1115
found to be susceptible to leaf blast
• Epidemic of blast in hybrid rice DY-69 was observed
in Kathamandu valley (Manandhar, 2017), however it
was found resistant in Surkhet and Khajura conditions.

43. • Among Local genotypes Pokharel Dhan, Dhunge Dhan,
Arabis, Srijana, Khajuwa, Basmati were found resistant in
both locations.
• The variations of the genotypes in the blast severity at
different locations suggest that the pathogen population
was highly variable and host genotype-specific.
• Genotypes showing resistant reaction in both locations
indicated wider adoptability capacity with respect to
climatic variation and presence of different races.

44. Category of 101 rice genotypes on the basis of mean AUDPC at RARS,
Category of 101 rice genotypes on the basis of mean AUDPC at RARS,
Khajura
Khajura
Category AUDPC Name of genotypes
Resistant
(R)
28
Up to 90 Sabitri, PR413 Dhan, Arabais Dhan-2, Srijana, Dhan-10, Pokharel Dhan,
Dhunge Dhan, Janaki, Radha – 4, US-312, Champion , DY- 69, Aakash
1115, Khajuwa, Sukha Dhan – 4, Hardinath – 1, GK – Marshal – 135, Tara
Gold 1112, Arabais, Hardinath – 2, Jhinna Dhan, Basmati, Swarna Sab-1,
Rampur Mansuli, Karmuli, Arabisdhan-1, Loknath- 505, Ghaiya 1
Moderately
Resistant
(MR) 15
91-180 Anjana, Dhan-1, Tarahara – 1, Anadi -2, Bhatte, Kalanamak, Ram dhan,
Sukha Dhan – 6, Makwanpur-1, Simtharo, Sukha Dhan – 1, Shyamjira-1,
Dhan-7, Mabilili Dhan, Saandaar
Moderately
Susceptible
(MS) 16
181-270 Radha–11, Dhan-5, Dhan-4, Anadi, Lalka basmati, Arabisdhan, Deradune -
1, Radha – 7, Shyamjira, Rahimanawa-1, Dhan -2, Dhan-6, Sano Mansaro,
Sukha Dhan–2, Black Rice, Dhan-8
Susceptible
(S)
39
271-420 Radha–11, Dhan-5, Dhan-4, Anadi, Lalka basmati, Arabisdhan, Deradune -
1, Radha – 7, Shyamjira, Rahimanawa-1, Dhan -2, Dhan-6, Sano Mansaro,
Sukha Dhan–2, Black Rice, Dhan-8 were moderately susceptible. Similarly,
39 genotypes viz. Darmali, Karangi, Goral, Gopaledhan, Gude Dhan-1, Jire
Dhan, Anadi -3, Sukha Dhan – 3, Karangi Dhan, Rato Dhan, Sukha Dhan –
5, Mansuli Dhan, Arabais Dhan-1, Radha Dhan, Hari Bhakte, Dehradune,
Dhan, Rahimanawa, Jhlingi Dhan, Dhan-3, Jire Dhan-1, Garima 1115, Kalo
Jaran, Jhayale Ghaiya 1, Gude seto , Damari Dhan, Dhan-9, Simtaro Dhan,
Tilki Dhan, Dedwa, Soto, gude Jaran Seto, Nibai Dhan, Anadi -1, Gaure
Dhan, Seto Gunde, Kalnathe Dhan, Jhayale Ghaiya, Rate Ghaiya

45. Category of 101 rice genotypes on the basis of mean AUDPC at Dashrathpur
Category of 101 rice genotypes on the basis of mean AUDPC at Dashrathpur
Category AUDPC Value Name of genotypes
Resistant
(R)
27
 90 Sabitri, Lokhnath 505, Sukha Dhan – 4, Khajuwa, Tarahara – 1,
Basmati, Hardinath – 1, Janaki, Tara Gold 1112, GK – Marshal – 135,
Simtharo, Ram dhan, Aakash 1115, Kalanamak, US-312, Champion,
Ghaiya 1, Pokharel Dhan, Sano mansaro, Srijana, DY-69, Dhan 1,
Arabais, Dhan, Dhunge Dhan, Shyamjira, Dhan-4
Moderately
Resistant
(MR)
17
91-180 Dhan-5, Darmali, Hardinath-2, Karmuli, Dhan-2, Anadi, PR 413
dhan, Bhatte, Anadi-2, Sukha Dhan 6, Mabali Dhan, Makwanpur 1,
Saandar, Jhinna Dhan, Anjana, Dhan-7, Radha 4
Moderately
Susceptible
(MS) 25
181-270 Rampur Mansuli, Gude Dhan 1, Sukha Dhan 1, Swarna Sab-1, Dhan
3, Arabais Dhan 1, Sukkha Dhan-2, Deradune-1, Radha 11, Dhan 6,
Arabaisdhan 1, Jire Dhan 1, Lalka Basmati, Dhan 8, Anadi-3, Black
rice, Goral, Arabais Dhan 2, Dhan 9, Mansuli Dhan, Dhan-10,
Radha7, Shyamjira-1, Sukha Dhan 3, Gopaledhan
Susceptible
(S) 11
271-420 Karangi Dhan, Sukha Dhan – 5, Rato Dhan, Jaran seto, Anadi-1,
Dedwa, Gude Dhan, Hari bhakte, Karangi, Jhlingi Dhan, Garima 1115
Highly
Susceptible
(HS) 20
420 Mansuli, Shankharikha, Tilki Dhan, Dehradune, Radha Dhan,
Kalnathe Dhan, Jhayale Ghaiya 1, Simtaro Dhan, Rate Ghaiya,
Jhayale Ghaiya, Kalo Jaran, Gaure Dhan, Rahimanawa, Rahimanawa
1, Jire Dhan, Soto gude, Damari dhan, Gude seto, Nebai Dhan

46. Category of 101 rice genotypes on the basis of mean AUDPC in both locations
Category of 101 rice genotypes on the basis of mean AUDPC in both locations
Category AUDPC Name of genotypes
Resistant
(R)
17
 90 Pokharel Dhan, Dhunge Dhan, Ghaiya 1, Arabis,
Srijana, Khajuwa, Basmati, Lokhnath- 505, GK-
Marshal 135, Tara gold 1112, US-312, DY-69,
Champion, Aakash 1115, Sukha Dhan-4,
Hardinath-1, Janaki
Moderately
Resistant
(MR)
8
91-180 Makwanpur-1, Saandaar, Anadi 2, Dhan-7,
Mabilili Dhan, Anjana, Bhatte, Sukha Dhan-6

47. CONCLUSION
• Among local genotypes Pokharel Dhan, Dhunge Dhan, Arabis,
Srijana, Khajuwa, Basmati among improved genotypes Sukha Dhan-
4, Hardinath-1, Janaki and among the hybrids Tara gold, Lokhnath
505, Aakash 1115, US 312, DY-69, GK Marshal 135, Champion were
recorded as resistant.
• Variation on disease severity among the genotypes was also observed
which may be due to variation in the genetic diversity of rice
genotypes.
• Some genotypes showed variations in disease reactions between the
locations. This may be due to the variation in the pathotypes; also the
variation on environmental condition.

48. Category of rice genotypes on the basis of mean AUDPC
Category of rice genotypes on the basis of mean AUDPC
Resistant
Resistant M. Resistant
M. Resistant M. Susceptible
M. Susceptible Susceptible
Susceptible Highly Susceptible
Highly Susceptible
Jire Dhan
Jire Dhan
Ram Dhan
Ram Dhan
Ghaiya 1
Ghaiya 1 Rahimanuwa
Rahimanuwa Gude Seto
Gude Seto

49. Resistant rice genotypes in both Location (Surkhet and Khajura)
Resistant rice genotypes in both Location (Surkhet and Khajura)
Hardinath-1
Hardinath-1
Janaki
Janaki Ghaiya-1
Ghaiya-1 Basmati
Basmati
Dhunge Dhan
Dhunge Dhan Pokhrel Dhan
Pokhrel Dhan
Khajuwa
Khajuwa
DY 69 US 312 Loknath 505
DY 69 US 312 Loknath 505

50. Disease Symptoms in Inoculum Plot
Disease Symptoms in Inoculum Plot
Resistant Check
Resistant Check
Sabitri
Sabitri
Susceptible Check
Susceptible Check
Shankharika
Shankharika

51. Some Glimpse Of The
Research Work

52. Advisors
Advisors
visiting the field
visiting the field

53. Field activities
Field activities

54. Laboratory activities
Laboratory activities

55. Acknowledgement
Acknowledgement
• Prof. Sundar Man Shrestha, Ph.D., AFU, Rampur
• Prof. Jaya Praksh Dutta, Ph.D., Dean, AFU, Rampur
• Prof. Kalyani Mishra Tripathi, Ph.D., Assistant Dean
(Examination) AFU, Rampur
• Prof. Bishnu Raj Ojha., Assistant Dean (Administration)
AFU, Rampur
• PG Co-ordinator
• External Examinar
• Bedananda Chaudhary, Ph.D., Senior Plant Pathologist
• Adjunct Prof. Hira Kaji Manandhar, Ph.D, AFU, Rampur
• NARC, NRRP, NGB, GRP, RARS, Khajura, ARS, Surkhet
• Lecturers, Seniors, Juniors and Friends and all my helping
hands