SCREENING OF POTENTIAL BACTERIAL BIO-CONTROL AGENTS AGAINST THE HELMINTHOSPORIUM ORYZAE IN-VITRO CONDITIONS. CAUSED BY BROWN SPOT OF RICE

Abstract

Brown spot of rice caused by Helminthosporium oryzae is one of the most destructive diseases of rice
worldwide. This disease causing rotting of seeds that ultimately reduce yield by 16-43%. This study was aimed
to evaluate bio-control agents under in vitro conditions against H. oryzae. The method followed was based on
survey and sampling of rizhospheric soils samples from Larkana district and surrounding areas. Rhizobacteria
were isolated from soil-rice plants and 25 isolates were studied for their antagonistic effect on the linear colony
growth of H. oryzae by using PDA medium as for growth. Results of the present study showed that the use of
bio-control agent (Rhizobacteria) against the tested fungus showed that, four isolates out of 24 bacterial isolates
has inhibited the linear colony growth of H. oryzae up to 1-2 mm with different levels (-, +, ++, +++).. The use
of bio-control agent Rhizobacteria like (Agrobacterium and Pseudomonas) isolates also showed antagonistic
activity against the tested fungus (H. oryzae). This study could be helpful for researchers and farming
community in future for better management of this disease.