Abstract:
The study, "Management of Phytophthora disease of black pepper
(Piper nigrum L. Walp) using plant growth promoting microbial
inoculants" was conducted at the Department of Plant Pathology, College
of Agriculture, Vellayani to investigate the effect of plant growth
promoting rhizobacterial strains belonging to fluorescent pseudomonads
and Bacillus spp. and the root endophytic fungus, Piriformospora indica
on the suppression of nursery wilt of black pepper incited by
Phytophthora capsici. Two strains of fluorescent pseudomonads viz.,
Pseudomonas putida strain 89B61 and P. jluorescens strain RCL3R4, two
strains of Bacillus viz., BY -1 and BY -2 and P. indica were included in the
study to explore their potential in plant growth promotion and disease
suppression. P. capsici inoculated control, uninoculated healthy control,
chemical control (0.20 per cent COC drenched at 15 days intervals) and
combined application of Trichoderma harzianum and an AMF, Glomus
fasciculatum were maintained for comparison. In the dual culture assay,
conducted in vitro for preliminary screening, though P. indica exhibited a
slight mycelial growth inhibition initially, the pathogen later overgrew the
antagonist. Among the bacteria, fluorescent pseudomonad strains
exhibited better mycelial growth inhibition 'on both PDA and Carrot Agar.
The influence of different biocontrol agents on growth promotion of the
black pepper cuttings was not statistically significant. However, the
fluorescent pseudomonad, P. putida strain 89B61 exhibited maximum
growth promotion. In the experiment conducted to test the potential of
vanous plant growth promoting microbial inoculants in suppressing
nursery wilt, the plants treated with spore suspension of P. indica
exhibited the highest wilt percentage of 93.22 per cent which was more
than that in the inoculated control (37.48). The plants treated with the
fluorescent pseudomonad, P. jluorescens strain RCL3R4 recorded a wilt
percentage of 6.70. All other treatments were highly effective and
checked the infection completely. The Bacillus strain, BY -2 exhibited
better disease suppression in vivo. The fluorescent pseudomonad,
P. putida strain 89B61 also showed disease suppression in vivo, which
indicated that it has the dual function of plant growth promotion and
disease suppression.
