Studies on plant growth promoting fluorescent pseudomonads of Uttara Kannada District of Karnataka State
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Date
2010
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UAS Dharwad
Abstract
Of the 133 fluorescent pseudomonads from Uttara Kannada district, 86 were
identified as Pseudomonas fluorescens, 45 as P. aeruginosa and two as P. aureofaciens.
Seventy isolates released 11.85 to 60.60 % Pi at 14 days. The IAA and GA production ranged
from 30-984 μg/l and 55-342 μg/l of broth respectively and 22 isolates produced cytokinins
(4.07-58.44 μg/l). While 67 produced alkaline protease, 28 had high chitinolytic activity.
Sixty-seven isolates antagonized one or other plant pathogens; 49 were inhibitory to A.
carthami, 39 to F. oxysporum f. sp. carthami (Foc), 32 to S. rolfsii, 23 to R. bataticola, 42 to
X. axonopodis pv. punicae (Xap), 59 to X. axonopodis pv. malvacearum, 42 to R.
solanacearum and 41 to X. axonopodis pv. citri. Of these, 41 produced HCN and all of them
produced siderophores. Out of 28 potential antagonists, 26 produced antimicrobials. Five
antagonists against each of the 4 fungal pathogens produced volatile metabolites which
inhibited S. rolfsii, A. carthami and Foc. Fifteen isolates with multifunctional properties were
evaluated in pot cultures. In safflower, DF 75 was the best for growth promotion. When
safflower was challenged with Foc, MDF 449(1) recorded best growth promotion coupled
with the least wilt incidence and highest ISR activity. In pomegranate, MDF 449(1) was best
for growth promotion. When pomegranate was challenge inoculated with Xap, DDF 347(1)
showed maximum growth promotion coupled with the least bacterial blight intensity and
highest ISR activity in leaves. The RAPD analysis of 25 isolates indicated tremendous
diversity. The dendrogram for pooled data showed nine clusters. The Shannon’s index of
pooled data was 0.71 indicating high diversity the maximum being in dry deciduous forest
(0.79). The richness index was 0.65 indicating that fluorescent pseudomonads are not
distributed equally. Low evenness index of 0.26 indicated dominance of P. fluorescens over
the others.