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

Studies on the Phytophthora Nicotianae Var. Nicotianae – a New Pathogen of Brinjal in Bangladesh

Md. Sakhawat Hossain
Senior Scientific Officer
Plant Pathology Division, BARI, Gazipur

I. H. Mian
Professor
Plant Pathology Department, BSMRAU, Gazipur

Abstract/ Executive Summary:

Phytophthora fruit rot of brinjal (Solanum melongena L.) caused by Phytopthora nicotianae var. nicotianae was recorded first time in Bangladesh. Different aspects of causal pathogen in relation to temperature were studied in vitro. Incidence and severity of fruit rot disease was high at 25 to 30°C, and pathogen could not infect the host below 20°C. Mycelial growth and sporangia production of the fungus on oat meal agar (OMA) medium was maximum at 25°C. Sporangial germination occurred over a wide range of temperature (10 - 35°C), and the number of sporangia germinated at 30°C. Optimum temperature for zoospore liberation was 25°C and zoospore liberation decreased with increasing or decreasing temperature from 25°C, and no zoospore formed at 5°C. The zoospore germinated at 10 to 30°C though 20°C was the best for their germination.

Keywords: Phytophthora nicotianae, Brinjal, Fruit rot

Location: Plant Pathology Division, BARI, Gazipur

Start Date: 01-08-1997

End Date: 31-10-1997

Program Area: Pest Management

Commodity: Diseases

Objectives:

The present study was undertaken to study the effect of temperature on disease development, mycelial growth and reproduction of the fungus Phytophthora nicotianae var. nicotianae

Methodology:

Isolation and pathogenicity test of the pathogen: Diseased fruit of brinjal were collected from the field and the symptoms were recorded. Pathogen were isolated from infected fruit and studied under microscope for mycelial character, sporangiophores, sporangia, presence or absence of chlamydospore and sex organs were studied. For testing pathogenicity of the fungus healthy full-grown brinjal fruits were surface sterilized, pricked gently with needle and artificially inoculated with mycelia and spores of the test fungus. The infection court were wrapped with moistened cotton and kept in polyethylene bags to maintain humid condition. The test fruits, in bags, were incubated at 29±2°C and examine regularly. After 2 days symptoms of the disease were appeared and the fungus was reisolated from the infected fruit.

Effect of temperature on disease development: Full-grown brinjal fruits were inoculated with test fungus and put in polyethylene bag (five for each temperature) and incubated at 15, 20, 25, 30 and 35°C. Uninoculated fruits were used for each level of temperature for comparison. After 4 days data on disease development were recorded by measuring the diameter of lesion. Disease severity was also graded as according to Hossain and Mian 2000.

Effect of temperature on mycelial growth, sporangia production and sporangial germination: Four mm diameter actively growing mycelial block was placed at the centre of OMA plate (90 mm). Five plates were used for each temperature regime The inoculated plates were incubated at 10, 15, 20, 25, 30 and 35°C for 4 days. Mycelial growth was estimated by measuring the diameter of the colony. For sporolation 8 mm cottony mycelial discs, cut from 10 days old culture, were placed at the centre of petridishes containing 10 ml sterilized tap water and incubated at 10 to 35°C. After 3 days, the average numbers of sporangia formed were recorded based on 15 microscopic field at450x. The percentage of sporangial germination was also computed.

Effect of temperature on liberation and germination of zoospore: Mycelial blocks (8mm) bearing sporangia were transferred to sterilized petridishes containing 10 ml fresh tap water and incubated at 10 t0 35°C. After six hours of incubation zoospores `discharged from sporangia were recorded according to Sastry and Hedge (1989) with some modification.

Source of Information: Bangladesh J. Plant Pathol.16: 43 - 46. 2000

Article Link (Online Journal):

Funding Source:

1. Government

Budget:

Total Budget (Tk.) :

Achievement/Findings:

Isolation and pathogenicity of the causal pathogen: The fungus was identified as Phytophthora nicotianae var. nicotianae waterh. In pathogenicity test all the inoculated fruits got infected and characteristic rotting symptoms developed within 3 – 4 days. The same pathogen was reisolated from the diseased fruits.

Effect of temperature on disease development: At 20 - 35°C all the inoculated fruits were infected within 4 days after incubation but the pathogen failed to infect fruits at 15°C. The diameter of lesion was maximum at 30°C followed by 25°C. The severity of the disease was also maximum at 25°C and 30°C.

Effect of temperature on mycelial growth, sporangia production and sporangial germination: The mycelial growth and sporangia production were the highest at 25°C whereas maximum number of sporangia germinated at 30°C. Percentage of sporangial germination at 25 and 30°C were statistically similar but mycelial growth and sporangia production at 25 and 30°C differ significantly. Lower mycelial growth was recorded at 15 and 35°C but the fungus did not grow at 10°C.

Effect of temperature on liberation and germination of zoospore: The highest number of zoospores liberated at 25°C and maximum zoospore germination was recorded at 20°C. any variation in temperature from 20 - 25°C adversely affected the liberation and germination of zoospore. Zoospore liberation and germination did not occur at 5 and 35°C.

Knowledge Management: Journal