The health problems caused by extensive use of agrochemicals in rice cultivation in
Sri Lanka necessitates investigations on alternative, less harmful methods of
maintaining productivity and for disease management. Endophytic fungi (EF) of
many plant spp. have been reported to have the ability to enhance plant growth
through the synthesis of Indole Acetic Acid (IAA) and to possess mechanisms of
fungal pathogen control. Therefore, the present study was carried out to evaluate the
levels of IAA production by the EF isolated from two rice varieties Bw 367 and
Suwandel with the aim of using them for increased crop productivity. Preliminary
screening of growth inhibition of two rice pathogens by the EF was also carried out
as a means of using them in disease management. Healthy plant samples of rice
varieties Bw 367 and Suwandel were collected during the Yala and Maha seasons
(2019) from Anuradhapura, Kurunegala, Gampaha and Kalutara districts, in Sri
Lanka. Endophytic fungal spp. were isolated onto 2 % Malt Extract Agar medium.
The isolates were identified based on morphological features and molecular
characterization of the ITS region of rDNA.
A total of 256 isolates belonging to 30
fungal genera were isolated from the two rice varieties and IAA production by these
fungal isolates was then evaluated using Salkowski’s assay. The effect of the isolated
EF on the growth of Rhizoctonia solani and Bipolaris oryzae, the causative agents of
Sheath blight and Brown spot diseases of rice respectively was also tested under invitro conditions using the dual culture assay. Amongst the tested isolates,
Microdochium fisheri and Dendryphiella sp isolated from Suwandel produced IAA
at significantly high levels of 12.7 fig mL'1 and 10.0 |ig mL'1 respectively (P<0.05).
Dual culture studies revealed that Penicillium oxalicum and Fusarium falciforme
isolated from Bw 367 inhibited the colony growth ofR. solani by 65.3 % and 53.5 %
respectively whilst the growth inhibition of B. oryzae was less at 36.9 % by both. The
study indicated that some of the EF associated with the selected rice varieties have
the ability to produce the growth promoting phytohormone IAA whilst some others
have the means to control the growth of two common rice pathogens and have the
potential to be used for increased productivity of rice as well as for the control of the
two rice diseases after further testing.
