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Effect of Farmers Seed Management Practices on Seed Borne Fungi of Rice

S. M. A. Haque
Principal Scientific Officer
Plant pathology Department, BJRI

Abstract/ Executive Summary:

Blotter method of testing of the seed samples of three Boro and three T. Aman varieties of rice collected from 21 selected farmers after different management activities. Storage was found to be the most important factors that affected the population of associated fungi significantly. In both the seasons, three distinct trends of population dynamics of some of the associated fungi were observed for different species of fungi like, (i) population increased significantly after storage- species of storage fungi like Aspergillus flavus, A. candidus and Penicillium sp. were fall under this category; (ii) population decreased significantly after storage- Fusarium semitectum, Cladosporium cladosporioides and Nigrospora oryzae; (iii) gradual decline- only Fusarium moniliforme was found under this category in both the seasons. The pathogens, which differed in their incidence pattern with respect to season, were Biporalis oryzae (gradual decrease in Boro and sharp decrease after storage in T. Aman), Curvularia spp. and Trichoconis padwickii (sharp decrease in Boro but no trend in T. Aman), Pyrenochaeta oryzae and Tilletia barclayana (increased after storage in Boro but no trend in T. Aman). In case of Microdochium oryzae and Sarocladium oryzae no such trend was found in any of the seasons.

Keywords: Rice, Pathogen, Boro, Aman

Location: The present investigation was carried out in farmer's field and house of village Myzbag under Ishwargonj upazilla of Mymensingh district and in the glass- house and laboratory of Plant Pathology Division, Bangladesh Rice Research Institute, Gazipur

Start Date: 01-12-2001

End Date: 31-12-2002

Program Area: Pest Management

Commodity: Rice

Objectives:

To find out if there is any influence of different management practices on the population of seed- borne pathogens.
To find out which management is most effective in reducing the pathogens.

Methodology:

Collection of seed samples

A total of 42 seed samples of 6 rice varieties e.g. BRRI Dhan28, BRRI Dhan29 and Gazi (BR14) during Boro 2002 and BR11, Pajam and Kiranmala were collected during T. Aman, 2001 season from purposively selected 21 farmers of Ishwarganj upazilla under Mymensingh district. The seed samples from each of the farmers were collected after different management activities i.e.- after harvesting, threshing, cleaning, drying, storage and soaking by the farmers. Harvesting of Boro varieties was done in May and June and that of T. Aman varieties in December. For seed storage four types of containers viz., Plastic drum, Tin, Motka and gunny bag were in both the seasons. Farmers seed management/processing activities of the locality are shown in Table 1. At each sampling 500g seed was collected from each of the farmers after every activities from harvesting to subsequent soaking for sowing in the next season. Collected samples were placed in clean brown paper bag, labelled properly and preserved at 5-8⁰C temperature in refrigerator for subsequent use.

Detection of seed borne fungi

The samples were tested by blotter incubation method for detection of major seed borne fungi following standard blotter method (ISTA, 1996) with little modification. Two hundred randomly picked seeds of each sample were placed on three layers of moist blotting paper (Whatman No. 1) contained in 9cm diameter plastic petridishes. Twenty-five seeds were placed in each petridish. The seeds in the petridishes were incubated at 25±2⁰ C under 12 hours cycle of alternate Near Ultra Violet (NUV) light and darkness. Each seed was observed under stereo binocular microscope in order to record the presence of fungal colony 7 days after incubation. In doubtful cases temporary slides were prepared from the fungal colony and observed under compound microscope. Appropriate keys (Booth, 1971; Misra et al., 1994b; Benoit and Mathur, 1970; Ellis, 1971 and Malone and Muskette, 1964.) were consulted for identification of the fungi. The results were expressed as percent incidence.

Statistical analysis

Factorial Randomized Complete Block Design (RCBD) was used to analyze the data. The factors were different management practices and variety. The measurement variables were prevalence of the population of different fungi associated in relation to management practices and variety and interaction of varieties and seed processing activities were subject to ANOVA. Least Significant Difference (LSD) was done to determine the differences among the treatments.

Source of Information: M.S. Thesis (2002) of S. M. A. Haque, Plant pathology Department, BJRI

Article Link (Online Journal):

Funding Source:

Budget:

Total Budget (Tk.) :

Achievement/Findings:

Three distinct trends of population dynamics of some of the associated fungi were observed for different species of fungi like, (i) population increased significantly after storage- species of storage fungi like Aspergillus flavus, A. candidus and Penicillium sp. fell under this category; (ii) population decreased significantly after storage- Fusarium semitectum, Cladosporium cladosporioides and Nigrospora oryzae; (iii) gradual decline- only Fusarium moniliforme was found under this category in both the seasons. The pathogens, which differed in their incidence pattern with respect to season, were B. oryzae (gradual decrease in Boro and sharp decrease after storage in T. Aman), Curvularia spp. and Trichoconis padwickii (sharp decrease in Boro but no trend in T. Aman), Pyrenochaeta oryzae and Tilletia barclayana (increased after storage in Boro but no trend in T. Aman). In the case of Microdochium oryzae and Sarocladium oryzae no such trend was found in any of the seasons. Incidence of Phoma glumarum was increased significantly after soaking but was similar after harvesting to after storage. In general, storage fungi were found to increase while in the storage and field fungi decreased. Significant interactions among varieties and seed management practices were observed in some pathogens in both seasons.

Knowledge Management: Thesis