Agricultural Research Management Information System

Home
Research Summary
Search
About Us
- ARMIS
- Brochure
Contact Us
Report
User Request
Data Input
Help
- Operation Manual
  - PDF
  - Video
- Program Area & Commodity
We have reached 37600 number of research entries at this moment.

- Logout

Research Detail

Home
Research
Detail

Study on Rotting of Onion Genotypes Developed by the Department of Genetics and Plant Breeding, BSMRAU, Gazipur

Prof. Dr. Md. Abu Ashraf Khan
Professor
Department of Plant Pathology, Bangabandhu Sheikh Mujibur Rahman Agricultural University, Gazipur 1706

Abstract/ Executive Summary:

Rotting of onion genotypes developed by Department of Genetics and Plant Breeding, BSMRAU, Gazipur was studied during 2007-08. Percentage of average onion bulb rotting was 38.37 and 31.51, respectively by weight and number. The lowest rotting was recorded in variety Taherpuri by both weight and number basis. Rotting of different onion genotypes was caused by two fungi, one bacterium and by physiological disorders. The fungi were Aspergillus niger and Penicillium sp. In case of fungal infection dry rot was observed whereas in case of bacterial infection soft rot was observed. Dry rot was also produced due to physiological disorders where no biotic agents were observed. Percentages of average rotting by A. niger, Penicillium sp., bacteria and physiological disorders were 21.53, 6.60, 1.78 and 3.68%, respectively. On the basis of different properties studied, the bacterium isolated from onion bulb was identified as E. carotovora sub sp. carotovora. A. niger and Penicillium sp. were involved in dry rot, and E. carotovora was involved in soft rot of onion bulb in storage. All 10 isolates caused rot in carrot, cucumber, onion, cauliflower, chilli, turnip, brinjal and radish. It suggested that the identified bacteria have wide host range

Keywords: Onion, Genotype, Rotting,

Location: Department of Plant Pathology, BSMRAU, Gazipur 1706

Start Date: 01-07-2007

End Date: 31-06-2008

Program Area: Postharvest and Agro-processing

Commodity: Onion

Objectives:

i. Determination of losses of onion bulbs of different genotypes due to rotting in storage ii. Isolation and identification of causal agent of rotting of onion bulb in storage.

Methodology:

Twenty three onion genotypes and one well known variety Taherpuri were used in this experiment. Data on rotted onion (by weight and number) was taken at every 15 days interval. Rotted bulbs were collected to the Plant Pathology Laboratory and associated fungi and bacteria were isolated and identified. Isolation and Identification of fungi: The fungi associated with onion bulb were detected under a binocular sterio-dissecting microscope and identified based on the morphological characters using appropriate keys (Singh et al. 1991). Temporary mounts were prepared and examined under a compound microscope when the identification of fungi was not possible by observing the growth characteristics under steriomicroscopoe. Isolation and pathogenicity test of bacteria: Bacterial isolates were isolated from soft rotted onion by “streak-plate” method as described by Schaad (1988). Altogether 10 pathogenic isolates were isolated and these isolates were used in various tests for identification and characterization of the pathogen. Two standard isolates Erwinia carotovora sub sp. carotovora ATCC 15713 and Erwinia chrysanthemiv Ura 2 were used as reference strains. Pathogenicity of the selected soft rotting bacterial isolates was tested on the original host (onion) from which they were isolated, and on brinjal, carrot, cauliflower, turnip, radish, chilli, and cucumber. Identification of bacterial isolates The isolated bacteria were identified following rapid extraction Thin Layer Chromatography using lipid profile (Khan and Matsuyama 1999) and by physiological and biochemical tests (Schaad 1988).

Source of Information: Research Report, Personal contact with Principal Investigator

Article Link (Online Journal):

Funding Source:

1.	Budget: 50,000.00
2.	Budget: 50,000.00

Total Budget (Tk.) : 50,000.00

Achievement/Findings:

Rotting of different onion genotypes was caused by two fungi, one bacterium and by physiological disorders. The fungi were Aspergillus niger and Penicillium sp. In case of fungal infection dry rot was observed whereas in case of bacterial infection soft rot was observed. Entire or partial onion bulb was rotted. Watery slimes were exuded from the rotted bulb and bad smell was produced. Dry rot was also produced due to physiological disorders where no biotic agents were observed. Percentages of average rotting by A. niger, Penicillium sp., bacteria and physiological disorders were 21.53, 6.60, 1.78 and 3.68%, respectively. The chromatographic profiles of lipids from 10 pathogenic isolates showed identical results with that of reference strain Erwinia carotovora subsp. carotovora ATCC 15713. On the basis of different properties studied, the bacterium isolated from onion bulb was identified as E. carotovora subsp. carotovora. From the results it was clarified that A. niger and Penicillium sp. were involved in dry rot, and E. carotovora was involved in soft rot of onion bulb in storage. All 10 isolates caused rot in carrot, cucumber, onion, cauliflower, chilli, turnip, brinjal and radish. Symptoms caused by the isolates were water soaked and soft rot with brown colour. The foul-smelling slime exuded from the rotted tissues. The reference strains E. carotovora subsp. carotovora ATCC 15713 and E. chrysanthemi Ura –2 gave similar result. It suggested that the identified bacteria have wide host range

Knowledge Management: Report/Proceedings