STUDIES ON VARIABILITY AND MANAGEMENT OF SAFFLOWER (Carthamus tinctorius Linn.) WILT INCITED BY Fusarium oxysporum f.sp. carthami KLISIEWICZ AND HOUSTON
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Date
2004
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ACHARYA N. G. RANGA AGRICULTURAL UNIVERSITY RAJENDRANAGAR, HYDERABAD
Abstract
Variability among eleven isolates of Fusarium oxysporum f.sp.
carthami, the causal agent of safflower wilt collected from different
locations of Andhra Pradesh, Maharashtra and Karnataka in India was
studied with respect to cultural, morphological characters, pathogenicity
and protein profiles. In addition to these, biological control of the
disease using the local isolate was also studied.
Significant variation was observed with respect to size of
microconidia, macroconidia and chlamydospores of FOC isolates when
grown on potato dextrose agar (PDA) medium. The size of micro and
macroconidia ranged from 8.02 –14.76 x 2.66 – 2.93 μm and 17.40 –
26.82 x 4 – 4.53 μm. Longest microconidia (14.76 μm) was produced by
the isolate FOC 11(Annigeri) and shortest microconida (8.02 μm) by the
isolate FOC 8 (Aurangabad). Largest macroconidia (26.82 μm) was
produced by the isolate FOC 5 (Parbhani I) and shortest macroconidia
(17.46 μm) were produced by isolate FOC 7 (Solapur). The diameter of
chlamydospores of isolates ranged from 5.83 μm to 9.50 μm. The isolate
FOC 3 (Latur) produced largest chlamydospore (9.30 μm), while the
isolate FOC 1 (DOR) produced smallest chlamydospore (5.83 μm). No
distinct variation was observed with shape of microconidia,
macroconidia and chlamydospores of test isolates.
Variation was observed in colony characters, colony growth,
mycelial dry weight and sporulation among the test isolates. The isolates
FOC 1 (DOR), FOC 2 (Tandur) and FOC 8 (Aurangabad) produced
fluffy white mycelium with whitish pink pigmentation while FOC 3
(Latur), FOC 4 (Phalton), FOC 6 (Parbhani II) and FOC 11 (Annegiri)
produced cottony white mycelium with whitish pink pigmentation. The
other isolates FOC 5 (Parbhani I) and FOC 10 (Akola II) produced white
fluffy mycelium with whitish yellow pigmentation and in addition
zonation was observed in FOC 5 isolate collected from Parbhani. Isolate
FOC 7 (Solapur) produced white cottony mycelium and FOC 9
(Akola I) produced fluffy white mycelium without any pigmentation
when grown on PDA medium. The colony diameter ranged from 51.60
mm (FOC 8) to 84.40 mm (FOC 9) seven days after incubation at
25 ± 1°C on PDA. The mycelial dry weight of FOC isolates ranged from
56.0 (FOC 8) to 252 mg (FOC 9) on potato dextrose broth (PDB) 10
days after incubation at 25 ± 1°C while, number of microconidia ranged
form 4.80 to 28.20 x 104 / mm2 and macroconidia ranged from 1.40 to
6.80 x 104 /mm2 on PDA medium 15 days after incubation at 25 ± 1°C.
Pathogenicity test with the isolates of F. o. f.sp. carthami showed
differential reaction on moderately resistant safflower cvs. HUS-305 and
A-1. Whereas, the cvs. Manjira and Nira were susceptible to all the test
isolates. Wilt incidence ranged from 21 to 66.66 per cent in moderately
resistant cvs. HUS-305 and A-1, while in susceptible cvs. Nira and
Manjira, wilt incidence was in the range between 73.33 and 100 per
cent. The isolates FOC 1 and FOC 2 induced >50 per cent wilt, while
the isolates FOC 4 and FOC 11 induced 21 – 40 per cent wilt in
moderately resistant cv. HUS-305. The isolates FOC 1, FOC 4 and FOC
10 induced >50 per cent wilt and FOC 3, FOC5, FOC 8 and FOC 11
isolates induced 21 to 50 per cent wilt incidence in moderately resistant
cv. A-1.
In electrophoretic studies, all the isolates of FOC showed five
common protein bands between molecular weights of 25 KDa to 45
kDa. The isolates FOC 3 (Latur) and FOC 9 (Akola I) showed common
protein banding pattern between molecular weights 66.2 to 116 kDa. A
total of nineteen bands were present in FOC 3 (Latur) isolate which was
less virulent. Whereas, seven bands were seen in the isolate FOC 1
(DOR) which was more virulent than the other test isolates.
In vitro evaluation of native isolates of T. viride, T. harzianum
and P. fluorescens against F. o. f.sp. carthami by dual culture technique
revealed that, T. viride was found superior in inhibiting the mycelial
growth of the test isolates of the pathogen as compared to T. harzianum
and P. fluorescens.
All the treatments involving bioagent, T.viride (native isolate)
have recorded significantly less incidence of wilt in safflower cv. Nira
and enhanced significantly the per cent seedling germination, shoot and
root lengths and dry weight compared to the pathogen check and
uninoculated control.
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Keywords
STUDIES, VARIABILITY, MANAGEMENT, SAFFLOWER