VARIABILITY AMONG THE ISOLATES OF Sclerotium rolfsii Sacc. FROM DIFFERENT HOST PLANTS
Loading...
Date
2013
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Birsa Agricultural University, Kanke, Ranchi, Jharkhand
Abstract
Sclerotium rolfsii Sacc. is soil inhabitant, non-target, polyphagous and an
ubiquitous facultative parasite. It is widely distributed in tropics, subtropics and also in
warmer parts of temperate zone of the world. It has wide host range infecting cultivated
crops viz., potato, groundnut, soybean, frenchbean, elephant foot yam, chickpea,
sunflower, chilli, tomato, cotton, lucerne, wheat and onion etc. The pathogen S. rolfsii
induces a variety of symptoms such as seed rots, seedling blight, collar rot, stem rot, wilt
in different host plants. It preferentially infects on stem, but can also infect root, leaf,
flower and fruit. In severely infected field, loss ranges from 10 to 25 per cent and
sometimes, it reaches upto 80 per cent . Twenty-one isolates of S. rolfsii Sacc. obtained
from Elephant foot yam, Groundnut, Frenchbean, Soybean, Potato and Chickpea plants
from different locations of Ranchi and Hazaribag district of Jharkhand and are
designated as EFY 1, EFY 2, EFY 3, EFY 4, EFY 5, EFY 6, EFY 7, EFY 8, EFY
9, EFY 10,GN 1, GN 2, GN 3, GN 4, GN 5, FB 1, FB 2, S 1, S 2, P and CP were taken
for investigation on variability. Pathogenicity test resulted that the isolates were capable
to infect their own host.
Morphological character studied on potato dextrose agar media revealed
considerable variation among the isolates. The colony diameter varied from 77.33-90mm
at 72 hrs of incubation. The color of mycelium was extra white to off white. Concentric
circle is present in twelve isolates and absent in rest of the isolates. Nine isolates
exhibited fluffy texture and rest were of compact texture. Fan like growth were found in
eight isolates. Variability in morphology of sclerotial bodies reported that number of
sclerotia per plate were varies from 42-485. The color of sclerotia was light brown to
dark brown. Size of sclerotia varied from 0.78-2.09 mm and they were round, spherical
or irregular in shape. The weight of 10 sclerotial bodies were recorded between 3.16-
14.87 mg. Days of maturity of sclerotia varied from 14-22 days. Arrangement of
sclerotia in the petriplate was peripheral, central or uniformly distributed. The present
investigation reveals that isolates comprised significant variation in morphological and
cultural traits of S. rolfsii indicating the presence of different strains of the pathogen.
The cross inoculation studies on different host revealed that among the twenty
one isolates of S. rolfsii the three isolate viz., P, CP, and EFY 6 were highly cross
infective and pathogenic to all hosts. Isolates EFY 1 and EFY 2 were moderately cross
infective and was pathogenic to five host and rest were less infective. On the basis of
susceptibility of host plant, frenchbean, chickpea and groundnut were found to be highly
susceptible, Potato was moderately susceptible and elephant foot yam and soybean were
susceptible host.
Among the pesticides, 2, 4-D completely inhibited the mycelial and sclerotial
growth of S.rolfsii of all the isolates. Chlorpyriphos is the next effective pesticide
followed by Paraquat, Carbofuran and Imidachloprid. Thiomethoxam was the least
effective pesticides.
Description
VARIABILITY AMONG THE ISOLATES OF
Sclerotium rolfsii Sacc. FROM DIFFERENT
HOST PLANTS
Keywords
null