A. K. M. Shahed Bin Mannan
Research Officer
Centre for Innovation and Development Strategy (CIDS), Rampura, Dhaka
A. M. Akanda
Professor
Department of Plant Pathology, Bangabandhu Sheikh Mujibur Rahman Agricultural University (BSMRAU), Gazipur
M. K. A. Bhuiyan
Professor
Department of Plant Pathology, Bangabandhu Sheikh Mujibur Rahman Agricultural University (BSMRAU), Gazipur
A. K. M. S. Islam
Leaf Extension Executive
British American Tobacco Co. Ltd., Kushtia, Bangladesh
Seed potato, Incidence of PVY, Yield, Tuber grade
Field at the Bangabandhu Sheikh Mujibur Rahman Agricultural University (BSMRAU), gazipur-1706
Variety and Species
Experiments conducted-The experiment was conducted in the field at the Bangabandhu Sheikh Mujibur Rahman Agricultural University (BSMRAU), gazipur-1706 during potato growing season 2006-2007. The materials used and methods in the experiments are described below. In experimental field the soil belongs to Salna series under the Agro Ecological Zone (AEZ)-28: Madhupur Tract. The texture of the soil was silty clay in surface layer and silty clay loam in subsurface layer (Rahman et al., 1998). The pH of the soil was 6 to 6.5. The climate of the area is characterized by heavy precipitation during April to September and scanty or no rainfall during October to March 2006-2007. Collection of potato seed tubers- Seventh generation seed potato of six different varieties namely Baraka, Remarka, Victoria, Voyager, Bellini and Diamond were used in the experiment to evaluate their, disease incidence, growth and yield performance against PVY. Seed tubers were collected from plant pathology laboratory, department of plant pathology, Bangabandhu Sheikh Mujibur Rahman Agricultural University (BSMRAU), Gazipur. Land preparation and fertilizer application- The experimental field was mechanically ploughed and leveled to have a good tilth at late November 2006. Before preparation of the land, cow dung @ 10 t/ha was applied. The crop was fertilized with 350, 250, 270, 120, 120, 10, 6 kg/ha of Urea, TSP, MP, Gypsum, Magnesium sulphate, Zinc sulphate and Borax, respectively as recommended by Tuber Crop Research Centre (Anonymous, 2005). One half of the Urea and full dose of all other fertilizers were applied prior to planting. The rest half of the Urea was applied 25 days after planting when first earthing up was done. Planting and intercultural practices-The seventh generation of all the varieties of seed tubers were planted maintaining 60 m x 30 cm spacing. The unit plot size was 3 m x 1.8 m. The experiments were set up in Randomize Complete Block Design (RCBD) with three replications. The crop was raised following usual cultural practices such as irrigation, weeding, earthing-up etc. were done as and when necessary. Haulm killing and harvesting- Haulm killing was done ten days before harvesting with a view to avoid the spread of viruses and for hardening of tuber skin. The crop was harvested 95 days after planting and the healthy and PVY infected tubers of each plant was kept separately in net bags separately for further study. Grading of tubers-The grading of tubers were into four different groups following the standard of BADC as < 28 mm, 28 - 40 mm, 41-55mm and >55 mm which was designated as Under, A, B and Over respectively. Aphid counting by yellow water trap- Two yellow water traps (‘Moericke’ yellow trap) were placed in two different locations of the experimental field to catch the aphid vectors. The trapping initiated from the first week of January, 2007. Half of the yellow trap was filled with tap water where few drops of liquid trix soap were added so that the aphids could not fly after falling on the traps. The number of aphids were counted one day interval at 5 pm. up to the date of haulm killing. The water of the traps was changed every time after aphid counting. Counting of Healthy plants, PVY infected plants in the field- To observe the symptoms of PVY the plants of the plots were checked visually from the date of emergence to record the number of plants infected with PVY. Identification of PVY infected plants- PVY incidence was identified based on symptomatological study, mechanical inoculation test and Double Antibody Sandwich Enzyme-Linked Immunosorbent Assay (DAS-ELISA). Symptomatological study- The identification of PVY infected plants was done mainly through visual observation of typical symptoms. Plant showing rugosity (mosaic plus all kinds of deformation of leaves), weak to severe necrosis, dwarf and brittle with leaves wrinkled and bunched together and finally death of the plants was identified as PVY infection. Some varieties showed both rolling and severe necrosis at the margins of the older leaves. Later on healthy and PVY infected potato plants were confirmed by indicator plant inoculation test and DAS-ELISA using the kit prepared by Agdia Incorporated, USA. The protocol was followed as written in the manual supplied by the manufacturing company. Asymptomatic plants are considered as healthy which was also confirmed by DAS-ELISA. Double Antibody Sandwich Enzyme-Linked Immunosorbent Assay (DAS-ELISA)- The plants grown in the experimental field were tested using DAS-ELISA (Pathoscreen Kit, supplied by Agdia Incorporated, USA) to reconfirm the identification of PVY infection and healthy plants noted based on symptomatology and indicator plant test. The wells of microtiter plate were examined by eye as well as measured by Immuno-Reader NJ2000 at 405 nm to find out the absorbance value. Wells in which yellow colour develops indicated positive results. Wells which remained colourless indicated negative results. The validity of colour development was confirmed comparing with the results of the positive and negative control.
Data Collection
The data were collected on the following parameters.
I) Plant height
II) Numbers of stem/plant
III) Number of tuber/plant
IV) Number of tubers / plant under different grades according to following the description of
International Potato Center (CIP).
V) Yield / plant on the basis of tuber weight
Design of experiment and statistical analysis- Randomized Complete Block Design (RCBD) was followed with 3 replications. Analysis of variance (ANOVA) was performed using MSTAT-C software. Data were transformed as and when necessary. Mean separation was done through Duncan's Multiple Range Test (DMRT). Meteorological data- Meteorological data such as temperature, relative humidity and rainfall were collected from the weather station of Bangladesh Meteorological Department, Agromet Division, Bangladesh Agricultural Research Institute, Joydebpur, Gazipur.
J.Soil.Nature. 2 (3): 68-75, (2008)
Journal