The landrace rice Dawk Pa-yawm Rai variety was highly resistant to 18 blast isolates,
moderately resistant to 5 and susceptible to 2 blast isolates. Therefore, Dawk Pa-yawm Rai
variety was broad-spectrum resistance to many blast isolates and can be used as genetic
resource in breeding programs for blast disease resistance. The genetic inheritance of blast
resistance in F2 population was identified. Seven hundred and thirty F2 plants from a cross
between KDML105 (recipient) and Dawk Pa-yawm Rai (donor) were generated. The disease
assessment revealed 524 F2 plants were resistant and 206 F2 plants were susceptible. The
segregation of resistance and susceptible phenotypes showed a goodness of fit to the ratio 3:1
(R:S). The result found is important factor and useful in mapping of blast resistant gene in
Dawk Pa-yawm Rai variety.