Abstract:
Blast of rice caused by Pyricularia oryzae fungus which played vital roles in
reducing yield of rice in Bangladesh from last two years. The prevalence of rice
blast was remarkable in greater Dinajpur district including Thakurgaon and
Rangpur. The blast samples were collected from the farmers field of selected area
of Dinajpur, Thakurgaon and Rangpur districts which were reported to have blast
infection by the regional agricultural extension centers during Boro season 20172018.
Blast infected leaf, node and neck samples were collected for the in-vitro
study. The in-vitro study was carried out at the Molecular biology and Plant
virology laboratory, Dept. of Plant Pathology, Sher-e-Bangla Agricultural
University, Dhaka. The main objectives of this experiment was to isolate the blast
pathogen and to identify the best culture media for pathogenic growth and
sporulation of Pyricularia oryzae, to study its morphological and pathogenic
characteristics. From the study, it was revealed that Carrot Rice straw Dextrose
Agar (CRDA) was found for the best mycelial growth and sporulation of
pathogen. The morphological study of the derived three isolates from the field
samples, it was evident that the disease was caused by Pyricularia oryzae, as the
isolates produced hyaline, pyriform three celled conidia (average 16.45 × 7.46
µm) from leaf sample and CRDA media, respectively. They were able to reestablish
the disease in in-vitro pathogenicity test. In-vivo study was also carried
out by using Blast susceptible rice variety BRRI dhan 28 to assess the efficacy of
Potassium Silicate (K
2
SiO
3
) in different doses (0, 1, 2, 4, 8, or 10 g L
Si),
number of sprayings at pH 5.5. Silicon (Si) is known as a “beneficial element” for
plants. The direct and indirect benefits of the element for crops (especially
grasses) are related to resistance to diseases, pests a drought. From this study it
was found that spraying of K
2
SiO
3
ii
at 4 g L
-1
significantly reduce the blast disease
incidence and severity.
Description:
A Thesis
Submitted to the Faculty of Agriculture,
Sher-e-Bangla Agricultural University, Dhaka,
In partial fulfillment of the requirements
for the degree of
MASTER OF SCIENCE
IN
PLANT PATHOLOGY
