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Longevity of Bipolaris Oryzae on Heera-2 Hybrid Rice Seed

US Monira
Department of Plant Pathology, Bangladesh Agricultural University, Mymensingh-2202, Bangladesh

MA Ali
Department of Plant Pathology, Bangladesh Agricultural University, Mymensingh-2202, Bangladesh

A Sultana
Department of Plant Pathology, Bangladesh Agricultural University, Mymensingh-2202, Bangladesh

R Islam
Department of Plant Pathology, Bangladesh Agricultural University, Mymensingh-2202, Bangladesh

Abstract/ Executive Summary:

Seeds of hybrid rice variety Heera-2 were collected from Mymensingh district in Bangladesh. The longevity of Bipolaris oryzae was studied from 2012 to 2016 at Seed Pathology Centre, Bangladesh Agricultural University, Seed processing &preservation center and Seed Pathology Laboratory of Supreme Seed Company Limited. The data collected from the experiments were analyzed for the test of significance and compared the treatment means by using DMRT at a 5% level of probability following the Statistical tool for Agricultural Research (STAR) 2.1 program. The longevity of B. oryzae was observed for five years by blotter incubation methods, seedling symptom test and growing on the test. Both untreated and seeds treated with Vitaflo 200FF (carboxin and thiram) were kept in a jute bag and polybag stored for five years under both normal and dehumidified condition. The inocula of B. oryzae on Hybrid Heera 2 seed remained viable for up to five years. When the seed samples were stored under dehumidified conditions, the highest incidence of B. oryzae was recorded in the case of jute bag after five years. After treated with Vitaflo 200FF, there was no infection of B. oryzae under both storage condition

Keywords: Bipolaris oryzae, Heera-2, Hybrid rice, Longevity, Seed

Location: Seed Pathology Centre, Bangladesh Agricultural University, Bangladesh

Start Date: 00-06-2012

End Date: 00-06-2017

Program Area: Seed Technology

Commodity: Rice

Objectives:

Objectives of this research to study the longevity of B. oryzae in hybrid rice seeds by pre-storage seed treatment and interaction thereof with storage conditions and containers.

Methodology:

The longevity of seed-borne fungi was studied at the Seed Processing and Preservation Centre Trishal, Mymensingh and Seed Testing Laboratory, Uttara, Dhaka of Supreme Seed Company Ltd. from June 2012 to June 2017. A seed lot having higher percentage of infection of B. oryzae was selected. A lot of Heera-2, a cultivar highly prone to seed-born B. oryzae was used. Seed treating fungicide Vitaflo (Carboxin 17.5% & Thiram 17.5%) was seed treatment against B. oryzae. Both treated (with vitaflo) and untreated seeds of Heera-2 were used. Twenty kg of seeds were taken at random. The sample was divided into four parts and taken in two in Jute bags & polybags separately. One half of both Jute bag & polybag were stored in the laboratory under the normal condition where temperature ranges was 11°C to 40°C, and relative humidity 40% to 98%. The other half was stored in the dehumidified chamber at temperature 18±2°C and 40% RH for five years. Four hundred seeds from each of the four seed samples were tested to examine the viability of B. oryzae on the infected seed. Blotter incubation method at four months’ interval was used. A number of incubated seeds with the growth of B. oryzae was observed under a stereomicroscope at 25 X and counted according to the keys outlined by Mathur and Kongsdal (2003). The percentage of seeds with the growth of B. oryzae on each sample in each test was compared and the duration of viability was determined. The experiment was continued for five years. The longevity of Bipolaris oryzae was studied under a controlled environment in a growth chamber using test tube agar methods. The infected seed was obtained from the seed lots collected from the same sample. Symptoms on the seedling were recorded and the pathogen was isolated and identified following the keys outlined by Mathur and Kongsdal (2003). The percentage of the seed/seedling showing the growth/sporulation of the pathogen was calculated. Bipolaris oryzae infected seed lots were identified based on the result of previous experiments. Four hundred seeds were taken from the working sample for testing its germination capacity. The infected seedlings were surface-sterilized with 1% sodium hypochlorite (NaOCl) and sown the sterile sand in plastic box using 100 seedlings/sample. Air was blown in the polyethylene bag by mouth before sealing the bag with a rubber band so that seedling does not touch the plastic. The disease was also monitored after 30 days by disease washing the seedlings to remove sand from the box. The number of infected seedlings was counted and confirmed by isolation of Bipolaris oryzae.

Source of Information: Environ. Sci. & Natural Resources, 12(1&2): 209-213, 2019

Article Link (Online Journal): DOI: https://doi.org/10.3329/jesnr.v12i1-2.52038

Funding Source:

Budget:

Total Budget (Tk.) :

Achievement/Findings:

The inocula of B. oryzae on Hybrid Heera 2 seed remained viable for up to five years. After five years, the incidence of B. oryzae was 15-28% in four varieties stored in the dehumidified chamber in jute bag while it was 8-20% stored under normal conditions in a polybag. After treated with vitaflo fungicides, there was no infection of B. oryzae under both storage conditions viz. normal (Tem 18-40°C, RH 40%-98%) and dehumidified (Tem 18±2°C, RH 40%) as well as in both containers till five years.

Knowledge Management: Journal