Shamim Shamsi
Department of Botany, University of Dhaka, Dhaka-1000, Bangladesh
Pranami Chowdhury
Department of Botany, University of Dhaka, Dhaka-1000, Bangladesh. Present address: Directorate of Secondary and Higher Education, Dhaka, Bangladesh.
In vitro evaluation, Fungicide, Plant extract, Rice sheath rot
The experimental field plots of BRRI (Bangladesh) and farmers field around Gazipur area, Dhaka, Bangladesh
Pest Management
Fungal Disease, Fungicide, Extract (plant, seed)
Sheath rot infected panicles with flag leaf sheaths were collected from experimental field plots of BRRI (Bangladesh) and farmers field around Gazipur area, Dhaka during July, 2014 to June, 2015 at booting, panicle initiation and grain stages of rice varieties BR11, BR12, BR16, BRRI25 - BRRI34 and Kataribhog. Thirty samples with sheath rot symptom was examined to detect the causal agent. Pathogen was isolated from the infected sheaths and grains following Blotter method and Tissue Planting method on PDA medium (Shamsi et al. 2010). Microscopic observation of the fungus was recorded on cover slip culture of the fungus. Identification of the fungus was determined following Ou (1985). Pathogenicity of the fungus was done following seed inoculation technique (Chowdhury et al. 2015). Rahman and Hossain (2009) reported that in Bangladesh Homai, followed by Bavistin, Tilt, Topsin-M and Tecto caused minimum DI (Disease intensity) in sheath rot. In the present investigation ten fungicides viz., Bavistin 50WP (50% carbendazin methyl benzimidazo-2-yl carbamate), Capvit 50 WP, Dithane M-45, Greengel, Hayvit 80 WP, Indofil M-45 (80% mancozeb manganese ion + ethylene bisdithio carbamate), Ridomil MZ Gold, Salcox 50WP (copper oxychloride), MC sulphur 80WP (80% sulphur) and Tall 25 EC (propiconazole) were selected due to their effectiveness against major rice diseases (Chowdhury et al. 2015). Fungicides were collected from Krishi Upokoron Biponi Kendro, Khamarbari, Farmgate, Dhaka. For each fungicide, a stock solution having the concentrations of 10,000 ppm was prepared. The calculated amount of the stock solution of a fungicide was supplemented with sterilized PDA medium to get the conc. of 100, 200, 300, 400 and 500 ppm. In the control set required amount of sterile water instead of fungicide solution was added to the PDA medium. Five mm mycelial agar disc cut from the margin of actively growing 7 days culture of test fungus and then it was inoculated at the centre of the plate. Three replications were maintained in both cases. Ten angiospermic plants viz. Allium sativum L. Artocarpus heterophyllus Lam., Asparagus racemosus Willd., Azadirachta indica L., Citrus medica L., Datura metel L., Mangifera indica L., Nerium indicum Mill., Senna alata L. and Tagetes erecta L. with antifungal properties were selected for in vitro evaluation of their ethanol leaf extracts on the vegetative growth of the test pathogen. Ethanol leaf extracts at 5, 10 and 20% concentration were evaluated against the pathogenic fungi following poison food techniques (Shamsi et al. 2014). Bulb of A. sativum and fresh leaves of rest of the nine plants was separately washed in tap water, air-dried and was prepared by crushing known weight of fresh materials with ethanol in ratio 1: 1 (w/v). The mass of a plant part was squeezed through four-folds of fine cloth and the extracts were centrifuged at 3000 rpm for 20 minutes to remove particulate matter. The supernatants were filtered through Whatman filter paper No.1 and the filtrate was collected in 250 ml Erlenmeyer flasks. The requisite amount of the filtrate of each plant extract was mixed with PDA medium to get 5, 10 and 20% concentration. Sarocladium oryzae was also grown on PDA plates with 5, 10 and 20% of ethanol. PDA plate without addition of plant extract served as control. The radial growth of the colonies was measured at the fifth day of incubation. The per cent growth inhibition of the test fungus was calculated by using the following formula: I = {(C-T) / C} x 100. where, I = per cent growth inhibition, C = growth in control and T = growth in treatment.
Bangladesh J. Sci. Res. 29(1): 47-54, 2016 (June)
Journal