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KUVEMPU UNIVERSITY DEPARTMENT OF P. G. STUDIES AND RESEARCH IN
APPLIED BOTANY Jnana Sahyadri, SHANKARAGHATTA – 577 451
A Dissertation Entitled
DIVERSITY OF PYRICULARIA ORYZAE CAVARA. ON PADDY CROPS IN SHIMOGA
DISTRICT
Presented by
Mr. CHANDRASHEKAR, D.G.
Guided by
Prof. M. KRISHNAPPA
CONTENTS
1. INTRODUCTION
2. REVIEW OF LITERATURE
3. AIMS AND OBJECTIVES
4. CONTROL AND MANAGEMENT OF BLAST
5. MATERIALS AND METHODS
6. RESULTS AND DISCUSSION
7. CONCLUSION
REFERENCES
INTRODUCTION
Rice (Oryza sativa L.) is one of the most important crops of the world both in terms of area (152 mha) and production (585.6 mt) and major food crop for Asia. Rice is not only a major staple but also exports commodity since last ten years (Siddiq, 2002). Sixty percent of world population depends on paddy, the byproduct of rice milling rice husk and bran are used a cattle and poultry feed. Rice is main food source for more than 60 per cent population in the country. Chhattisgarh is famous as ‘Rice Bowl’ in India. Origin of Rice Archaeologists of India have found charred grains of rice in Mohenjodaro of ancient Indus civilization. Apart from it, rice grains dating back to 2000 B.C. has been found in excavations of Lothal and Rangpur in Gujarat. Rice grains were also obtained at archeological sites of Japan, China, Korea and Thailand indicating its culture in ancient era.However rice is not mentioned in Bible. Evidence indicates that it was cultivated in Nile Valley around AD 640. Alexander, the great Greek Conqueror brought rice from India during his invasions. His teacher and Philosopher, Aristotle called the rice as Oryzon and mentioned in his botanical records. Thus rice was introduced first in Europe by Alexander. Indicia rice’s were carried by seafaring traders to Malaya and Java and later to Sri Lanka in 543 B.C.
Table 1. Major pathogens of paddy
Disease Causal organism SymptomsCountry from
which disease was first reported
Fungal diseases
Blast of paddy
Pyricularia oryzae. Cavara
Leaf spot, leaf blast, neck blast
Italy
Brown spot Drechslera oryzae / Helmininthosporium oryzae
Seedling, bright brown, leaf spot, leaf blight, sesame spot pecky rice, black sheath rot
Cosmopolitan
Bunt Tilletia horridea Tak. Sticky spores, stunted appearance
Japan
False smut Green smut
Claviceps oryzae sativa Ustilagenoidea virens
Grains into large green mosses
India
Udbatta disease
Ephelis oryzae Syd. Incense stick like panicles, black ring
India
Stack burn Trichococomis padwickii Stack burn, seedling blight, pnk kernel, leaf spot
Louisiana and Texas
Leaf smut Entyloma oryzae Leaden black coloured spots
-
Bacterial disease
Bacterial leaf blight of paddy
Xanthomonas compestris. Closon pv. oryzae.
Small water soaked lesions
-
Viral disease
Tungro disease Rice tungro virus Syn. Interveinal chlorosis Mild. Mottling, yellowing, stunting
-
Nematodal diseases
Ufra disease Ditylenchus angustus Buttler.
Withering and death of seedlings, chlorosis.
India
White tip Aphelenchoides besseyi Infected seeds, nematodes lie in quiescent stage beneath half of the seeds
-
Table 2. Details of paddy production in Karnataka
YearYear Production (in million tonnes)Production (in million tonnes)
1990-911990-91 74.2974.29
1991-921991-92 74.6874.68
1992-931992-93 72.8672.86
1993-941993-94 80.380.3
1994-951994-95 81.8181.81
1995-961995-96 76.9876.98
1996-971996-97 81.7381.73
1997-981997-98 82.5482.54
1998-991998-99 86.0886.08
1999-20001999-2000 89.6889.68
2000-012000-01 84.9884.98
2001-022001-02 93.0893.08
Source : http: //raitamitra.kar.nic.in.statistics.html
In Karnataka, paddy is grown in Shimoga, Chikmagalur, Chitradurga, Raichur, Mandya, Dakshina Kannada, Belgaum and Mysore which occupies 14.83 lakh hectares. Among that 10.71 lakh hectares of irrigated and 4.12 lakh hectares under rainfed condition. The annual production amount 38.47 lakh tonnes in the year 2000-01 accounts an average of 2520 kg/hectare. Karnataka stands 5th position in paddy production followed by Tamil Nadu, Andhra Pradesh, Maharashtra and overall India.Rainfall plays an important role in getting good yield and also in blast development. Heavy rainfall and relative humidity 90% influences blast at high rate (Kapoor, 2002).
Shimoga district had an total geographic area of 8,47,784 hectares comprising 2,76, 855 hectares of forest, 1,01,605 hectares under non agricultural usage and remaining 4,69,324 hectares under cultivation of various crops. A total rainfall of 1703 mm is recorded between May to October months of 2006. The district paddy occupies 1,33,436 hectares comprising 28.43% of land under cultivation (Statistical Department, DC Office, Shimoga).
Origin of Pyricularia oryzae
Pyricularia oryzae causal organism of leaf spot, leaf blast and neck blast symptoms and is first reported from Italy (Cavara, 1891 and Gangopadhyay, 1983). Rice blast occurs in 80 rice growing countries causing considerable yield reduction. The disease is believed to have occurred in Japan as early as 1704. The causal organism was however identified almost 200 years later in Italy in 1891. In India the disease was first reported in Tanjavore district in 1918.
Nearly 30 fungal diseases affect rice in India of these blast is one of the most significant diseases since crop damage can be as high as 70-80%.
Fig. 1. Disease cycle of rice blast disease
Fig. 2. Mode of infection
A - Attachment of Conidia to the plant surfaceB - Germination of conidium by sending out a short germ tube. The apical end of the germ tube extends and form a ‘Hook’C - Formation of nascent appresoriumD - Melanin layer forms in the appressorial cellwall during the maturation of infectious stageE - Driven by turgor pressure peg is forced through the plant cuticle to infect leafF - Formation of intracellular ‘Bulbous’ hyphaeG - Spread of the infection followed by conidiation
Map 1. Study area Shimoga district
Map 2. Shimoga district forest map
Map 3. Shimoga district Land use / Land cover
map
REVIEW OF LITERATURE
Vijaya and Balasubramaniyan (2002) reported the significant difference among the dates of sowing in both the years (1996 and 1997) of experimentation for PDI (percent disease incidence) and grain yield maximum reduction in diseases incidence was observed, when the crop was transplanted on 27th July from the nurseries of early on 30th June followed by the nursery sow on 15th July. Maximum grain yield was obtained from the crop grown with the nursery sown on 30th June.
Kapoor et al. (2002) have analyzed 13 years (1984-1996) weather data revealed that the number of days with RH of 90% (47 and 27 days) during July to September, number of rainy days in a week and cloudiness was most critical factor in the development of rice blast epidemics during blast years of 1984 and 1992.
Misra et al. (1997) have found the essential oil of Callistemon lanceolatus recorded, inhibitory activity against the germination of Magnoporthe grisea at 3000 ppm. The mycelial growth was however completely inhibited by only at 8000 ppm, nevertheless, 8000 ppm registered complete inhibition for specifically to stored grain pathogens of rice.
AIMS AND OBJECTIVES
Survey and collection of paddy blast diseased material.
Cultural characteristics and conidial diversity of Pyricularia oryzae Cavara. in Shimoga district.
Pathogenicity study of Pyricularia oryzae on host plants.
CONTROL AND MANAGEMENT OF BLAST
In the present day fungicides play an important role in disease management, most of the early fungicides with low biochemical specificity. The fungicides are usually inorganic chemical constituents like copper oxychloride, aretan, ceresan, hinosan, kasumin, deuter, brestanol, organomercuric and organo sulphuric derivatives were least effective in control of the blast.
Gangawane (1997) found Kitazin-P is effective fungicide for P. oryzae. Dubey (1997) found Tricyclazole efficacy against blast was superior over the control of neck and node infection. Vidyasekaran et al. (1997) developed powder formulation of Pseudomonas fluorescence for control of blast. In test a seed treatment and foliar spray in four field trials is effectively control the disease and increased grain yield.
Chakraborty and Rao (1990) eliminated seed borne pathogens including P. oryzae by mandatory quarantine hot water treatment of 54C for 30 min. with 6 h spore soaking was tried against naturally infected seeds.
MATERIALS AND METHODS
Methods1. Survey and Collection of Paddy Blast Materiala. Surveyi. Geography
Shimoga is one of the twenty seven revenue district of Karnataka state in India. It is situated in the midsouth western part of the state. The district is situated between 13° 27" and 14° 39" N latitude and between 74° 38" and 76° 4" E longitude. The geographical area of the district as per survey of India 8439.3 sq.kms. Shimoga district divided into seven revenue administrative bodies called taluks, viz., Bhadravathi, Hosnagar, Sagar, Sorab, Shikaripur, Shimoga and Thirthahalli.
ii. TopographyThe Shimoga district clearly divided into two equal
parts depending upon physiographic factors. The eastern part of the district comprises of Bhadravathi, Shimoga and part of Shikaripur taluk. This region generally known as Maidan(plane land) and absence of rich forest. The western part of the district having Thirthahalli, Sagar, Sorab, Hosanagar and part of Shikaripur taluk known as malnad (hilly tract), this region lies in the part of Western Ghats of this region having moist, ever green forest belt. The district slopes from west to east. The general elevation is 529 to 640 MSL.
2.Isolation of P. oryzae from Diseased Material
Before isolating a fungal pathogen from diseased material, the tissue should be examined for fruiting bodies and mycelium. Most of fungal pathogens attacking aerial parts of the plant body readily sporulate on the host, if kept moist at a suitable temperature, making isolation of pathogen easier. If spores are present on the diseased surface, a few spores may be shaken loose over a Petri plate containing wet blotter (Aneja, 2007).
Standard Blotter Method
The blotter method is used widely, since it is simple and inexpensive means of detecting pathogens of leaves for fungi, which readily form mycelial growth on leaves. This method provides optimum conditions for a number of fungi. The disease infected rice leaf discs were plated on two layers of moist blotter discs kept in 9 cm plastic petridishes at equidistant, that each plate contains 5 to 8 discs, these plates were incubated for 5 days under 12h/12h under normal lab conditions. The occurrence of associated mycoflora with P. oryzae were identified on fifth day using stereo-binocular microscope (Agarwal and Sinclair, 1993).
Preparation of potato dextrose agar
Method of inoculation
For this purpose, following procedures are adopted,Agar plant culture of the pathogen is selected out and take freshly sterilized culture medium, in which culture is to be inoculated.
To the sterilized media a pinch of antibiotic was added to avoid the bacterial contamination and it was poured into the sterilized glass petriplates.
After solidifying of the media, the P. oryzae culture present on the incubated leaf material was taken in a needle and it was inoculated into the centre of the petriplate near the flame.
All these procedures are done in aseptic condition in the laminar air flow chamber.
Inoculated petriplates were incubated in a incubation chamber at 20 to 40C for 5 to 7 days.
3. Pathogenicity Study of P. oryzae on Host Plant
Phylloplane is a natural habitat on leaf surface which supports heterogenous population comprising both pathogens and non pathogens. There are two methods viz.,
1. Serial dilution plate method and
2. Leaf impression method
Here serial dilution plate method was conducted to confirm the pathogenicity test.
FINDINGS
Table 3. Land use pattern of the study area during Kharif season (June to October), 2007
TalukTaluk Area of cultivationArea of cultivation PaddyPaddy Forest (in Forest (in hectares)hectares)
BhadravathiBhadravathi 42,55142,551 20,97220,972 18,23918,239
HosnagarHosnagar 17,87317,873 12,24612,246 35,02735,027
SagarSagar 26,26126,261 16,54816,548 66,12566,125
ShikaripurShikaripur 49,97249,972 31,15331,153 40,17340,173
ShimogaShimoga 45,33845,338 23,83423,834 42,89242,892
SorabaSoraba 44,69944,699 30,68430,684 26,66726,667
ThirthalliThirthalli 25,67225,672 16,82616,826 47,73747,737
Total Total 2,29,7332,29,733 1,52,2631,52,263 2,76,8552,76,855
Table 4. Temperature (in centigrade) and relative humidity (%) of the study area
during kharif season (June to October), 2007
MonthsMonths
Temperature (Temperature (C)C)Relative Relative Humidity Humidity (RH) (%)(RH) (%)MinimumMinimum MaximuMaximu
mm
JuneJune 18.0018.00 34.2534.25 94.0094.00
JulyJuly 17.0017.00 32.5032.50 93.5093.50
AugustAugust 16.2516.25 31.7531.75 90.0090.00
SeptemberSeptember 17.5017.50 33.5033.50 92.0092.00
OctoberOctober 17.2517.25 34.5034.50 92.0092.00
NovemberNovember 18.5018.50 30.0030.00 91.5091.50
Table 5. Area of paddy cultivated under irrigated and rainfed conditions during Kharif season (June to October), 2007
TalukTaluk Rain fedRain fed IrrigatedIrrigated
BhadarvathiBhadarvathi 3,9523,952 17,02017,020
HosnagarHosnagar 6,2666,266 5,9805,980
SagarSagar 12,80212,802 13,45913,459
ShikaripurShikaripur 11,86611,866 19,28719,287
ShimogaShimoga 7,3917,391 16,44316,443
SorabaSoraba 8,9608,960 21,72421,724
ThitrthalliThitrthalli 3,5883,588 13,23813,238
Source : http://www.shimoga.nic.in.
Table 7. Leaf spot observation in the field
Taluk
August 2007 September 2007 October 2007
No of spot/ leaf
Lesion length
Avg. (mm)
No of spot /leaf
Lesion length
Avg. (mm)
No of spot /leaf
Lesion length
Avg. (mm)
Bhadravathi 2364
2323
2.50
1473
2145
3.00
3549
5323
3.25
Hosnagar 10886
8646
6.00
961012
5887
7.00
111098
9687
7.50
Sagar 9786
4675
5.50
8579
6485
5.75
8745
8656
6.25
Shikaripur 2425
3421
2.50
3521
3245
3.50
4312
1645
4.00
Shimoga 6435
6412
3.25
8653
6423
3.75
7532
1647
4.50
Soraba 2453
1322
2
8243
4531
3.25
3416
6432
3.75
Thirthalli 7465
6534
4.50
5896
10832
5.75
9131011
8493
6.00
Table 8. Colony characters of the isolates of P. oryzae
Taluks Isolate
Colony Characters
Type Zonation Shape ColourDiameter
(mm)Dry weight
(mg)
Bhadravathi Po1 Subaerial Indistinct Irregular Grey 23 59
Po2 Subaerial Indistinct Irregular Grey 31 86
Hosnagar Po3 Aerial Distinct Circular Dull white 52 140
Po4 Aerial Distinct Circular Dull white 58 152
Sagar Po5 Aerial Distinct Circular Dull white 48 96
Po6 Aerial Distinct Circular Dull white 50 136
Shikaripur Po7 Subaerial Indistinct Irregular Blackish 22 55
Po8 Subaerial Indistinct Irregular Blackish 28 82
Shimoga Po9 Subaerial Distinct Circular Grey 30 85
Po10 Subaerial Distinct Circular Grey 24 62
Soraba Po11 Subaerial Indistinct Irregular Dull white 26 78
Po12 Subaerial Indistinct Irregular Dull white 22 57
Thirthalli Po13 Aerial Distinct Circular Grey 46 92
Po14 Aerial Distinct Circular Grey 42 88
Table 9. Cultural characters of fourteen isolates of P. oryzae collected from different geographical regions (Taluks) of Shimoga
Characters P. oryzae isolate
Taluks Bhadravathi Hosnagar Sagar Shikaripur Shimoga Soraba Thirthalli
Colour of Colony (reverse)
Black Black Black Black Black Black Black
Colony colour Greyish black Greyish white
Greyish white
Greyish black
Greyish white
Greyish white
Greyish white
Colony appearance ++ ++++ ++++ ++ +++ ++ +++
Branching pattern (Angle)
Left Left and Right
Left and Right
Left Right Left Left and Right
Formation of septum in the branch near origin
Indistinct Distinct Distinct Indistinct Distinct Distinct Distinct
Shape of conidia Obclavate Pyriform Pyriform Obclavate Pyriform Obclavate Pyriform
Colour of colony (reverse): Black /White Colony colour: Blackish grey / Dull WhiteColony appearance: ++ Less feathery, +++More feathery , ++++MaximumfeatheryBranching pattern: Right angle / Acute angle Shape of conidia: Obclavate / Pyriform
Field showing blast symptoms at Hosanagar
Infected blades Infected sheaths Injured blades
PLATE - I
A close view of blast lesion
An enlarged view of blast lesion
PLATE - II
Brown spots Tillers showing brown spots
Sheath with reddish brown
spots
Early stage symptoms showing leaf blade
yellow
PLATE - III
Appresorium formation in P. oryzae
Characteristic conidia of P. oryzae PDA culture of P. oryzae
Neck blast : Lesions on panicles Spots on rice stalks
PLATE - IV
RESULTS AND DISCUSSIONPaddy (Oryza sativa L.) is the major food crop in the
world today. It is the major agricultural crop growing in 14.82 lakh hectares in Karnataka with an output of 37.34 million tonnes and also a major export commodity fetch a foreign exchange of 3,174.15 crores. South Africa is the major buyer of Indian rice. India ranks second among major rice growing countries followed by China (Singhal, 2003).
Blast disease is caused by P. oryzae is the most destructive cause serious losses in yield due to epyphytotics of the disease have been recorded in different regions. Hosanagar, Sagar and Thirthahalli has an severe incidence. It has been found to take a heavy toll, bringing about almost 30 to 50% loss of the crop. It is due to low night temperatures, hilly malnad climate and heavy rainfall.
Blast made its impact more on kharif paddy than the rabi paddy. The loss caused due to blast is negligible in rabi. Early records shows heavy incidence of blast in Shikaripur and Bhadravathi taluks. Now it was over to malnad part of the district comprising Thirthahalli, Sagar and Hosanagar taluks. It is rarely occur on panicles resulting in infertile chaffy grains leading heavy loss to mankind.
In the study area, occurrence of major pathogenic fungus shows variation in their incidence at different regions due to edaphic factors. Study area is divided into irrigated and rain fed conditions. This major pathogenic fungi is more prevalent in rain fed conditions than irrigated one. In kharif, 2007, the study area receives an 159 to 1243 mm rainfall, temperature was between 16 to 34C and relative humidity 89 to 94 % recorded.
The highest annual rainfall recorded in Hosanagar followed by Thirthahalli and Sagar with 4672, 3805 and 2684 mm respectively. The economy of the study area is mainly based on agriculture and 66.27% of the cultivable land under paddy cultivation. The paddy cultivation having two seasons viz., February to May (summer or rabi) and August to November (rainy or kharif). The paddy having two cultural practices i.e., under irrigated and rainfed conditions. The plain land of the study area (Shimoga, Bhadravathi and part of the Shikaripur taluk) under irrigation having two seasons.
In malnad region (Thirthahalli, Sagar, Sorab, Hosanagar and part of the Shikaripur taluk) under rainfed condition. Jyothi, Jaya and Diamond Sona, Ankur Sonum and Sonamasuri are the major cultivars in the study area. The yield was 2.2 to 2.5 tonnes per hectare.
The leaf spot observation in field during the study period reveals the development of blast epidemics from August to October was most severe in October or a month before harvest. Since the disease always prefer to occur at tillering or grain setting stages resulting in heavy yield loss. 2 to 8 leaf spots per leaf of minimum 1 mm recorded in Bhadravathi and maximum 9 mm recorded in Hosanagar. The average size of brown spots between 2 to 7.5 mm.
The blotter tests screening of pathogenic fungi during a month before harvesting showed its associated organisms like Penicillium notatum, Aspergillus niger, Fusarium moniliformae and Cercospora lunata were observed.
After 5 days of incubation on blotter and pathogenic colony of organism screened and inoculated on fresh PDA culture, for cultural characteristics. The cultural plates observed for cultural characteristics like colony colour (reverse), colony colour, colony appearance, branching pattern, formation of septum and shape of conidia among 14 isolates from 7 taluks of Shimoga district and they are tabulated for their diversity. Colony characters like types, zonation, shape, colour, diameter and dry weight’s are tabulated. Among 14 isolates of 7 taluks of Shimoga district and their diversity would be known.
The spore suspensions of pure culture is injected to healthy leaf for disease symptoms reveal P. oryzae at 10-4 concentration show similar symptoms to naturally diseased material is determined. Therefore, pathogenic fungi grow robustly on 10-4 concentration spore suspension evidenced that P. oryzae is the causal organism of the paddy blast disease.
CONCLUSIONRice production not only boosts for our economy, but also
provides food security to the nation. Our GDP is completely dependent on agricultural source. Rice is a crop, mainly affected by bacterial, fungal and viral diseases. But the extent of loss caused by fungal diseases are high and desirable. Earlier days, blast epidemic was severe in almost malnad regions. Now it is concentrated over hilly, high rainfall, humid conditions. Hosanagar, Sagar and Thirthahalli taluks recorded high blast occurrence, where plain (maidan) region recorded BLB followed by Udhbatta disease at high extent. Blast can be controlled by good cultural practices like early sowing to escape or to break life cycle of blast, proper forecasting methods, uneconomic alternate hosts (grass species) eliminated by weeding, chemically by the application of carbendazim and hinosan. By using resistant varieties, more application of FYM instead of urea, seed treatment with powder formulations of Pseudomonas fluorescence, hot water treatment at 54C for 30 min. with 6 h spore soaking was tried against naturally infected seeds, by use of eco-friendly based neem based formulations and by using antifungal botanicals like Vinca rosea, Lantana camara, Ocimum tenuliform, Solanum melongina, Azadirachta indica, Polyalthia longifolia, Aegle marmelos and Datura metel.
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