Abstract:
An experiment was conducted at Plant Pathology Laboratory, Oilseed Research
center, Bangladesh Agricultural Research Inistitute (BARI), Joydevpur,
Gazipur, Bangladesh to find out the effect of temperature on growth and
sporulation of Alternaria species the causal agent of Alternaria leaf blight of
mustard from 10 representative geographical locations of Bangladesh, during
November 2015 to March 2016. All the isolates showed high level of variability
in vitro in respect of radial mycial growth, colony colour, sub surface colour,
colony shape, colony texture, zonation (surface and sub surface), length and
width of conidia, beak length and number of septa. The maximum and minimum
radial mycial growth was recorded 90 mm in isolate NAT
and 83.67 mm in
isolate GAZ
Ab
, respectively at 14
Ab
days after incubation. Significant variation in
conidial length, width, beak and no. of conidia observed in all isolates. The
length of conidia ranged from 41.56 to 117.54µm with 3 to 11 transverse and 0
to 3 vertical septa. The width and beak length varied from 10.34 to 23.12 µm
and 16.78 to 72.65 µm ,respectively. Surface colour were olivacious green to
black and circular shaped colonies were observed in all isolates on PDA
medium. Colony texture were cottony to velvety. Subsurface colour varied from
light brown to black and pinkish. Zonation found in some isolates and some did
not produce on both surface and subsurface. All conidia were murifrom and
light brown to deep brown in colour. Potato Carrot Dextrose Agar mdium
(PCDA) and 25
o
C temperature were found optimum for different isolates for
mycelial growth and sporulation.
