Screening of Hybrid and Inbreed Rice Varieties against Tungro Disease Inoculated with Viruliferous Green Leaf Hopper (Nephotettix virescens)

Volume04-2016
Advances in Agricultural Science 04 (2016), 04: 45-52

Screening of Hybrid and Inbreed Rice Varieties against Tungro Disease Inoculated with Viruliferous Green Leaf Hopper (Nephotettix virescens)

Md. Belal Hossain 1*, Sania Akter Rozy 1, Hosna Ara Chowdhury Nisha 1
1Department of Plant Pathology, Sher-e-Bangla Agricultural University, Dhaka-1207, Bangladesh.

ABSTRACT

Five hybrid varieties namely BRRI Hybrid Dhan 2, BRRI Hybrid Dhan 3, Aloran, Jagoran, Shakti 2 and five Inbreed varieties namely BRRI Dhan 28, BRRI Dhan 29, BRRI Dhan 50, BINA 8 and BINA 10 were evaluated against incidence of rice tungro disease in pot condition. The effect of diseases on yield and yield contributing characters were also observed. The incidence of the disease varied significantly from one another. Among the hybrid varieties, Shakti 2 was recorded highly resistant to tungro disease where BRRI Hybrid Dhan 3 and Aloran were found highly susceptible. In case of inbreed varieties; BRRI Dhan 50 and BINA 8 were observed highly resistance to tungro disease where BRRI Dhan 29 was found highly susceptible. In this experiment every infected plant of both types of varieties (hybrid and inbreed) initiated lower number of tiller and panicle than untreated and uninfected plant with the increase of disease incidence which finally directly affects in yield.

Keywords: Rice, Hybrid, Tungro Disease, Green leaf hopper


Introduction

Rice (Oryza sativa) is a cereal crop under the family Gramineae. About 40 percent of the world’s population derives most of their calories from rice. In the world, the major rice growing countries are China, India, Myanmar, Indonesia, Bangladesh, Vietnam, Thailand, Philippine, Brazil and Japan. Almost 90 percent of the population of Bangladesh, Myanmar, Sri Lanka, Vietnam and Kampuchea are rice eaters (FAOSTAT, 2010). In Bangladesh, rice is grown in three distinct seasons, namely Aus (April to August), Aman (August to December) and Boro (January to June) covering almost 11.0 million hectares of land (DAE, 2010). The average world yield of rice is 3.84 ton/ha (Ahmed et al., 2013) while the total production of rice in Bangladesh is 2.44 ton/ha from Aus variety, 2.59 ton/ha from Aman variety and 4.37 ton/ha from Boro variety, respectively (BBS 2013-14). So, the average yield of rice per hectare in Bangladesh is extremely low as compare to other rice growing countries of the world for example China, India, and Vietnam etc.

There are so many constraints to increase the production of rice in Bangladesh of which disease and pest play a major role (Fakir, 1982). Asia’s hot and humid climate during the long and heavy monsoon provides the most favorable agro ecological environment for rice cultivation as well as diseases development. Thirty six fungal, six bacterial, twenty one viral and five nematode diseases are recorded in rice (Ou, 1985). So far in Bangladesh, about 31 diseases are recorded to occur in rice including 10 major diseases (Miah et al., 1985, Shahjahan et al., 1987). Major diseases are seedling blight, blast, brown spot, sheath blight and rot, bakanae, false smut, bacterial leaf blight (BLB), bacterial leaf streak, ufra and tungro disease. Among these diseases, tungro disease caused by virus played vital roles in reducing yield of rice. Tungro disease caused by Rice tungro spherical virus (RTSV) and Rice tungro bacilliform virus (RTBV) was first recorded in 1966 in Bangladesh and reported as the most damaging viral disease. Stunting of the plant along with yellowish or orange discoloration and twisting of the leaves (leaf blade), reduced tillering, delayed flowering etc. are the distinguishing symptoms of this disease. Due to the potential injury and unpredictability tungro outbreaks can cause yield losses up to 80% (Quazi et al., 2009). In view of the above facts the present study was conducted to investigate the incidence level of tungro disease and to know the most susceptible growth stage of rice due to this disease in mostly cultivated hybrid and inbreed varieties in Bangladesh.

 

Materials and methods

Experimental site

The experiment was conducted at agronomy farm of Sher-e-Bangla Agricultural University, Dhaka -1207, during the period from December, 2013 to June, 2014.

 

Variety selection and seeds collection

Five hybrids namely BRRI Hybrid Dhan 2, BRRI Hybrid Dhan 3, Aloran, Jagoran, Shakti-2 and five inbreed varieties namely BRRI Dhan 28, BRRI Dhan 29, BRRI Dhan 50, BINA 8, BINA 10 were selected for research which are mostly cultivated in Boro season in Bangladesh. Seeds were collected from Bangladesh Rice Research Institute (BRRI), Joydebpur, Gazipur, Bangladesh Institute of Nuclear Agriculture (BINA), Bangladesh Agricultural University, Mymensingh and BRAC center, Gazipur. After collection, seeds were sprouted and sowed in the seed bed for transplantation prepared by proper agronomic practices.

 

Layout and design

The experiment was laid out in Completely Randomized Design (CRD) with three replications. Each variety comprises three replications (three pots) and one control (one pot). So, the total number of pot was 40 (10×3=30 and 10×1=10).

 

Pot preparation and seedling transplantation

Pots were prepared manually by hand. Soil was collected from the field where seedlings were grown for transplantation. Three seedlings of thirty days old were transplanted in individual pot. Weeding and irrigation was done in the pot as and when necessary.

 

Rearing of green leaf hoppers in rearing cage in greenhouse:

The culture is usually started by collecting green leaf hoppers (GLH) (Nephotettix virescens) from the field. A greenhouse and rearing cages are the major items required for rearing GLH. The green house should be well lighted and should provide a suitable environment for growing plants throughout the year. The greenhouse is equipped with pan trays, rearing cages and earthen pots. The size of the trays depends on the size of the greenhouse and on the volume of the materials to be used. The trays must be deep enough to cover the basal parts of the potted plants. For rearing cages use mesh. A bottom less cage placed in a water pan tray and the plants (food plants of 10 days) with earthen pot sit in water. Potted plants sit in about 8 cm of water inside the cage to provide optimum humidity. Then inoculate the collected GLH in food plant inside the cage. Hoppers are usually collected through aspirator and Mylar also used to transfer the hopper from old plant to new one (Figure 1).

 

Figure 1: Rearing of green leaf hoppers in greenhouse; (A) Green leaf hoppers are reared on potted plants in the cage, (B) Green leaf hoppers are on potted plants, (C) Green leaf hopper in infected rice plants (food plants) with myler.

Inoculation of test plants with green leaf hopper

During tillering stage, pots (except control pots) were covered by net (1 mm pores) (Figure 2A). A significant number (7-10) of green leaf hoppers (Nephotettix virescens) was collected from rearing cage and reared to feed on covered rice plants (test plants) to transmit the disease (Figure 2B).

 

Figure 2: Inoculation of test plants; (A) test plants covered with 1 mm pores net, (B) Green leaf hopper associated with rice plant (after inoculation in pot condition under net).

Collection of data on disease incidence and yield contributing parameters

Three weeks after inoculation of GLH, the plants were scored based on visual observation of the disease symptoms. The data on the following parameters were recorded such as symptom on leaf blade or leaf sheath, % disease incidence, number of tiller/hill, time of panicle initiation, panicle/infected hill, panicle/control hill, % plant height reduction and reaction level to rice tungro virus.

 

Weather report

The data on average temperature, relative humidity and rainfall were recorded at different date from mini weather station, Department of Agronomy, Sher-e-Bangla Agricultural University, Dhaka 1207.

 

Data analysis

Data were analyzed statistically using MSTAT-C computer program. Data were transformed, whenever necessary, following arcsine transformation. Means of treatment were separated using Duncan’s Multiple Range Test (DMRT), (Gomez and Gomez, 1984).

 

Results and Discussion

After the artificial inoculation of tested rice plants with viruliferous insect vector rice green leaf hopper (GLH), the incidence of rice tungro disease was observed on both types of varieties as clearly shown in Figure 3 and 4. Results are also presented in Table 1.  In case of hybrid varieties, the highest incidence (66.67%) was found in BRRI Hybrid Dhan 3 and Aloran which also gave lower number of tillers and panicles than the control plants as a result they were categorized as highly susceptible to tungro disease. Among the hybrid varieties only one variety, Shakti 2 showed the highly resistance to tungro disease while Jagoran and BRRI Hybrid Dhan 2 showed moderate resistance (Figure 5). Among the five inbreed varieties, the highest incidence (66.67%), lower number of tillers (5/hill) and panicles (5) were recorded in BRRI Dhan 29 and categorized as highly susceptible to tungro disease, while no incidence was found in BRRI Dhan 50, BINA 8 and untreated/control plant and categorized as highly resistant. BRRI Dhan 28 and BINA 10 showed moderate resistance by showing (33.33%) incidence, 9 and 8.33 number tillers/hill; 7 and 6 number panicles (Figure 6). Latif et al., (2011) reported that among the inbreeds (35), BR10 and BR11 were susceptible to tungro. In contrast, BR5, BR22, BR23, BRRI dhan 27 and BRRI dhan 31, BRRI dhan 32, BRRI dhan 37 and BRRI dhan 38 were moderately resistant to tungro. Among the thirteen (13) hybrid varieties, IR69690H was susceptible to tungro, while IR67161H and sonarbangla1 were moderately susceptible to tungro. Only the hybrid IR68877H was moderately resistant to tungro. Islam et al., (2001) reported that inbreed varieties- BR 25, BRRI Dhan 28, BRRI Dhan 31 and BRRI Dhan 32 are moderately resistance to tungro while BR 11, BR 22, BRRI Dhan 34, BRRI Dhan 39 and BINA sail were severely infected by tungro. IR68877H and IR67161H hybrid lines were moderately resistant to tungro. However, IR69690H and Sonar Bangla 1 were moderately susceptible to tungro.

 

Figure 3. Comparison between control plant (A) and tungro infected plant (B) of Hybrid variety BRRI Hybrid Dhan 3 and Aloran

 

Figure 4. Comparison between control plant (A) and tungro infected plant (B) of inbreed variety BRRI Dhan 29

 

Table 1. Reaction of different rice varieties against rice tungro virus after inoculation with viruliferous rice green leaf hoppers

Variety Disease

incidence

and severity in hill

Number of tiller/hill Number of panicle Disease reaction
Inoculated plant Control plant Inoculated

plant

Control

plant

BRRI Hybrid Dhan 2 33.33 12 18 10 16 MR
BRRI Hybrid Dhan 3 66.67 7 17 6 15 HS
Aloran 66.67 7 20 7 17 HS
Jagoran 33.33 7 18 5 18 MR
Shakti 2 0 20 21 20 20 HR
BRRI Dhan 28 33.33 9 13 7 13 MR
BRRI Dhan 29 66.67 5 13 5 12 HS
BRRI Dhan 50 0 12 11 11 11 HR
BINA 8 0 11 12 10 10 HR
BINA 10 33.33 8.33 12 6 11 MR

HR= Highly Resistant, MR= Moderately Resistant and HS= Highly Susceptible

 

Figure 5. Incidence of hybrid rice varieties against tungro disease

 

Figure 6. Incidence of inbreed rice varieties against tungro disease

 

Conclusion

From the present investigation it has been found that the currently most cultivated hybrid and inbreed rice varieties in Bangladesh are got infection by tungro disease while artificially inoculated with viruliferous rice green leaf hopper. So, different measures are needed to prevent the infestation of insect vectors for managing the rice tungro disease with increase the yield.

 

References

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BBS, (2013-2014). Statistical Pocketbook of Bangladesh. Agriculture Wing. Government of the People’s Republic of Bangladesh. pp. 2.

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Fakir, G.A. (1982). An annotated list of seed borne diseases in Bangladesh Agricultural Information Service. Dhaka, Bangladesh. pp. 15-22.

FAOSTAT. (2010). Worldwide rice area harvest and production. FAO Statistical Yearbook 2011. Finance, Government of the People’s Republic of Bangladesh, Dhaka.

Gomez, K.A. & Gomez, A.A. (1984). Statistical Procedures for Agril. Res. 2nd End. Intl. Res. Inst. Manila, Philippines, 139-207.

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Miah, S.A., Shahjahan, A.K.M., Hossain, M.A. & Sharma, N.R. (1985). Survey of rice disease in Bangladesh. Trop.Pest management, 31(3), 208-213.

Ou, S.H. (1985). Rice Diseases.2nd ed. Commonwealth Mycological Institute, Kew, Surrey, England. pp. 61-96.

Quazi, S.A.J., Rahman M.M., Akter, S., Tuhina-Khatun, M. & Monsur, M.A. (2009). Assessment of Yield Loss due to tungro in Bangladesh. Bangladesh Journal of Plant Pathology, 25(1), 37-40.

Shahjahan, A.K.M., Duve, T. & Bonman, J.M. (1987). Climate and rice diseases. In weather and rice. IRRI, Los Banos, Laquna, Philippines. pp. 125-128.

 

 

 

 

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