Abstract:
Rice, the staple food in many countries including Sri Lanka, is subjected to diseases
that often place a major biological constraint on production. Among these diseases,
blast caused by (Pyricularia grisea), and bacterial leaf blight caused by (Xanthoonas
oryzae pv. oryzae) are grouped under the major important diseases in Sri Lanka. Non
aromatic varieties have mostly grown in the country at present however, aromatic rice
varieties have also gain the preference of consumers because of the associated flavour
and high quality. Resistance, the most desirable control measure, has been investigated
by researchers in several countries against important rice diseases. The objective of the
study was to screen some aromatic and non aromatic rice varieties for resistance against
blast and bacterial leaf blight diseases. Seven non aromatic rice varieties and four
aromatic rice varieties were screened against blast disease along with the variety
pachchiperumal as the susceptible check. Plants infected with blast disease (inoculum)
spread over the net arranged test and infector blocks. Disease severity was assessed
according to 1-4 scale. In another experiment, six non aromatic rice varieties including
pachchiperumal as susceptible check and four aromatic rice varieties were screened for
resistance to bacterial leaf blight (BLB) disease. Bacterial suspension was prepared by
mixing pieces of infected leaves with water and plants at maximum tillering stage were
inoculated by clipping method. Disease rating was done measuring the lesion length.
Significant difference (P=0.05) was observed among tested varieties in their reaction
against blast and BLB diseases. Variety puc hchiperumal was found susceptible to both
blast and BLB diseases. Among aromatic varieties, line 28 ING was resistant to rice
blast while lines 51/3 and 22/3 were found moderately resistant. LD-355, BW 267/3,
RU 102, BG 379/2 and AT 354 were the non aromatic varieties resistance to blast.
However, LD 356, a non aromatic variety was found moderately susceptible to rice
blast. All the four aromatic varieties and all the non aromatic rice varieties except
variety BJ-1, showed susceptible reaction with BLB disease
