Abstract:
Trichoderma virens has demonstrated effective in enhancing rice plant growth and
inhibition due to Narrow Brown Leaf Spot (NBLS) disease caused by Sphaerulina
oryzina. This study aimed to evaluate the influence of T. virens on rice plant growth
and its suppressive effect on S. oryzina. The pathogen was isolated from symptomatic
rice plants at the Faculty of Agriculture, Rajarata University of Sri Lanka and
confirmed based on the morphological and microscopic observations. In dual culture
plate assay, Trichoderma virens exhibited a 43% inhibition of mycelial growth of S.
oryzina. Pathogenicity was confirmed by Koch’s postulates. The efficacy of the T.
virens was tested in a pot trial with eight treatments: T1: only soil, T2: NBLS and soil,
T3: NBLS and T. virens, T4: NBLS and full Department of Agriculture (DOA)
recommendation, T5: NBLS, full DOA recommendation and T. virens, T6: NBLS and
half DOA recommendation, T7: NBLS and T. virens with half DOA recommendation,
and T8: NBLS and carbendazim 500 g. Trichoderma virens was applied with the
initial dose (2.5 × 106 spores mL-1) of a capsule form. Plant growth parameters were
analyzed by using repeated mixed effect model in SAS statistical software. In case
of plant growth parameters plant height and leaf number was counted. Plant height
was improved significantly compared to untreated control (T1), while the leaf number
remained not significant. Further, T. virens spores were viable and multiplied
throughout the experimental period with zero disease progression even in plants
inoculated with the pathogen. In conclusion, T. virens is a promising alternative to
chemical fungicides for managing NBLS in rice plants and offers plant height
increasement.
