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Variability Among the Isolates of Rhizoctonia Solani of Sheath Blight Diseases of Rice

Z R Moni
IAPP, Plant Breeding Div., Gazipur-1701

MHR Mukul
ARD, BRRI, Gazipur-1701

S Alam
Dept. of Botany, Rajshahi University, Rajshahi

M S Mian
Plant Pathology Div., BRRI,Gazipur-1701

M S Hossain
Training Division BRRI,Gazipur-1701

Abstract/ Executive Summary:

In-vivo and In-vitro experiments were conducted at Pant Pathology laboratory and BRRI fram Gazipur in T. Aus 2010. Twenty four isolates of rice sheath blight caused by Rhizoctonia solani collected from four different locations of Gazipur, Godagari, Tanor of Rajshahi and Comilla distract. Mycelial growth on PDA and virulence test on cultivar Purbachi in field were taken in this study. Standard protocol was followed for Isolation, purification and preservation of the isolates. Artificial inoculation was done at maximum tillering stage. Variation in mycelia growth among the isolates and virulence was found among those isolates. The highest growth rate was observed in TA-03 collected from Tanor, Rajshahi. The most virulent isolate was TA-03(DSI 23.06%) followed by GA-03. Fast growing isolates was observed more virulent than other.

Keywords: Myceial growth, Pathogenicity, Sheath blight disease of rice

Location: Pant Pathology laboratory and BRRI fram Gazipur

Start Date: 00-00-2010

End Date: 00-00-2010

Program Area: Pest Management

Commodity: Rice

Objectives:

To collect information on the extant of variability in R. solani from many isolates collected from different geographical locations in Bangladesh.

Methodology:

Twenty- four isolates were collected from Godagari and Tanore of Rajshahi, BRRI farm Gazipur and Comilla districts in Bangladesh from infected rice (sheath and leaf) samples T Aman. Out of them, seven samples from Gazipur, seven samples from Godagari, seven samples from Tanor, Rajshahi and three samples from Comilla district. Infected samples were cut into small pieces (approximately 5x5 mm per section) from the margin of the expanding lesion and soaked in sterile distilled water (SDW) for 2-3 min. Then surface sterilized by 5 % clorox (5.25% sodium hypo chloride) solution for 15 second and rinsed 3 times in SDW. These inocula were then transferred into water agar (WA) plates and incubated at 27⁰C for 12 hours. After incubation, single hyphal tip (approximately 1cm length) using stereomicroscope were cut from tip of the hypha showing mycelial characteristics of Rhizoctonia sp and transferred to PDA. Each isolate coded as GA-01, GA-02, TA-01, TA-02, GO-01, GO- 02 and CO-01, CO-02 etc based on locations. Relative virulence of the pathogen was assessed through artificial inoculation (5 days old culture) on cultivar Purbachi in the field in T. Aus following standard cultivation and management practices recommended by BRRI. Twelve meter long (each replication having 12 m long) and 1.2 m breadth plot was transplanted in 15 cm x 20 cm spacing. Artificial inoculation was done at the PI stage. The designs of the experiment were REBD following three replications. Twenty isolates of the fungus, seven from Gazipur (GA-01 to GA-07), ten from Godagari (GO-01 to GO-05) and Tanor (TA-01 to TA-05) of Rajshahi and three from Comilla (CO-01 to CO-03) districts were used in this trial. Five hills of each replication were inoculated at maximum tillering stage and data were collected from all the tillers of these inoculated hills. Incidence data and RLH (Relative Lesion Height) were taken after 15 days of inoculation from which disease severity index DSI = (1.62x –32.4) x A/100, DSI were calculated according to Hashiba and Ijiri (1989) as follows, x = vertical development of RLH of the uppermost lesion to total plant height (RLH) and A = percentage of diseased hills (Incidence) was calculated.

Source of Information: Eco-friendly Agril. J. 7(09): 81-84, 2014 (September); ISSN 1999-7957

Article Link (Online Journal):

Funding Source:

Budget:

Total Budget (Tk.) :

Achievement/Findings:

In recent years in Bangladesh, the incidence of ShB in rice-growing regions has increased through the use of cropping system characterized by high planting density, abundant applications of nitrogenous fertilizers and intensive monocroping. Such farming practices, together with pathogen’s saprophytic nature and wide host range, and the planting of susceptible varieties have led to the dissemination, establishment and persistence of the fungus in all rice producing areas.

Knowledge Management: Journal