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Seed-borne Infection of Sarocladium Oryzae in Br-11 Rice Seed

M. E. H. Sarker
Department of Plant Pathology,, Bangladesh Agricultural University, Mymensingh

M. A. Ali
Department of Plant Pathology, Bangladesh Agricultural University, Mymensingh

M. N. Parvez
Department of Plant Pathology, Bangladesh Agricultural University, Mymensingh

M. M. H. Chowdhury
Department of Plant Pathology, Bangladesh Agricultural University, Mymensingh

P. Dey
Department of Plant Pathology, Bangladesh Agricultural University, Mymensingh

Abstract/ Executive Summary:

The experiment was conducted in BR-11 rice field during T-Aman season. Seeds collected from more severely infected plants gave more discoloured and spotted seeds. Sarocladiun oryzae was detected from 46% of the discolored (grey) seeds, 22% of the spotted seeds and 2% of the healthy looking seeds immediately after harvest. Seed-borne infection of this pathogen had strong relation with the severity of infection of the mother plants. The seeds harvested from severely infected tillers had highest seed infection and consequently the rate of transmission of Sarocladiun oryzae was also high. The pathogen (Sarocladiun oryzae) was detected from embryo, endosperm and glumes of the infected seed.

Keywords: Rice, sheath rot, Sarocladium oryzae, seed-borne, infection.

Location: Mymensingh

Start Date: 00-00-2006

End Date: 00-00-2006

Program Area: Pest Management

Commodity: Rice

Objectives:

To examine the seed-borne infection of Sarocladium oryzae,

Methodology:

BR-11 rice fields of Agronomy farm, BAU, Mymensingh were severely infected by Sarocladium oryzae during the Aman 2006. Percent sheath area diseased (SAD) was recorded by eye estimation. Sheath rot severity was estimated by the following 1-6 grades established by the author. Grade, 1 = no severity, 2 = < 1% SAD, 3 = 1-10% SAD, 4 = 11-20 % SAD, 5 = 21-30% and 6 = >31% SAD. One hundred infected panicles from each of the grades (1-6) of sheath rot infection were collected. The seeds were preserved at 4⁰ C for future use. The seeds were tested by Dry inspection, Blotter and Agar plate method in the laboratory for detection of Sarocladium oryzae following the procedure described by Mathur and Kongsdal (2003). Dry inspection: Five panicles were randomly taken from each infection grade. The seeds were inspected individually with the help of a 10x hand lens. The seeds were sorted out into healthy, discoloured, spotted, partially filled and unfilled seeds. Weight of seeds (g) per panicle and their respective numbers in each of the categories were counted. The data were expressed as number of seeds per panicle and seed weight (g) per panicle was recorded. Blotter method: Ten panicles were randomly taken from each infection grade (1-6). The seeds were threshed separately. Five hundred seeds were randomly taken from each grade. Three layers of blotting paper (Whatman filter No.1) soaked in sterilized water were placed at the bottom of 9 cm diameter plastic petri-dishes and 25 seeds were placed. The plates were incubated for 7 days at 21±2⁰C under 12 hours alternating cycle of NUV light and darkness (ISTA, 1999). Individual seed was observed under stereomicroscope at 25-x magnification. For proper identification of the fungi, temporary slides were prepared from the fungal colony and observed under compound microscope. The fungus was identified with the help of keys suggested by Mathur and Kongsdal (1994). The numbers of seeds infected by Sarocladium oryzae, number of seeds infected by other pathogens were recorded and the data were presented in percentage. Agar plate method: One hundred seeds each of healthy, discoloured, spotted and brownish margin with grayish center were taken. Ten seeds were placed on the PDA in each pair of glass petri dishes. The seeds were incubated for 5-7 days at 21±2⁰C under alternating cycles of NUV light and darkness. Colony characters and morphology of the fungus were studied. The numbers of seeds affected by Sarocladium oryzae were counted and expressed in percentage. Data were analyzed following MSTAT program.

Source of Information: Bangladesh J. Seed Sci. Technol. 13(1&2): 61–64 (2009), ISSN 1029-8800

Article Link (Online Journal):

Funding Source:

Total Budget (Tk.) :

Achievement/Findings:

Seed-borne infection of this pathogen had strong relation with the severity of infection of the mother plants. The seeds harvested from severely infected tillers had highest seed infection and consequently the rate of transmission of Sarocladiun oryzae was also high. The pathogen (Sarocladiun oryzae) was detected from embryo, endosperm and glumes of the infected seed. The maximum 46% seed infection by Sarocladium oryzae was found in brownish margin and grayish centre symptom expressing seeds. This symptom on seed may be considered as typical symptom of sheath rot of rice caused by Sarocladium oryzae. There is no information available in the literature about the symptom on seed caused by Sarocladium oryzae.

Knowledge Management: Journal