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foaming stability 96.2 %; water absorption production in Rhizoctonia solani. Bang. J. Life,
capacity, 340.0; oil absorption capacity, 120.0 %;
-1
emulsion capacity 30.0 mLg ; emulsion stability
-1
38.4 mLg ; least gelation capacity, 16.0% and
-1
bulk density 0.5268 mg . The protein solubility of
the P. Africana was found lo have minimum
solubility at pH 4.5.
105 HOSSAIN, M.A. (Plant Pathology
Division, BRRI, Gazipur) & KHAN, M.R. (Dept.
of Botany, Dhaka University, Dhaka). Survival of
Xanthomonas oryzae pv. oryzae and Its Virulence.
Bang. J. Microbiol., 2005, 22 (1), 41-46.
The experiments were conducted to find out a
simple, easy and cost-effective method of
preservation of the bacterial blight pathogen
Xnthomonas oryzae pv. oryzae having stable
virulence. The survival and virulence of the
pathogen of bacterial blight pathogen tested were
preserved in different substrate media. Clay
suspension (CS) and modified clay suspension
media (MCS) were found better for survival of
the pathogen though the survivility and virulence
properties varied among the strains tested.The
survival of all the strains in CaCl 2 was better and
virulence most strains but BXo373 (67.0 %) was
less affected. A disadvantage of this method of
preservation was that the bacterium could not be
isolated beyond two years. The bacterium could
survive in CS and MCS for more than 7 years but
the virulence was not very much affected up to 3
years of preservation. Survival of the bacterium
in peptone water (PW) was only about one year.
The bacterial population dynamics during
preservation in different substrate media, CS and
MCS, gradually decreased from an initial count
10
3
of 10 cfu/ml to a final count 10 cfu/ml.
Virulence property of the bacterium was affected
by prolong preservation in different substrate
media that might be due to mutation at the
virulence genes.
106 KHANDAKER, M.M. (Dept. of Botany,
Govt. Saadat College, Tangail); BHUIYAN,
M.K.A. (Plant Pathology Lab., Bangabandhu
Sheikh Mujibur Rahman Agricultural University,
Gazipur) & KHAIR, A. (Dept. of Botany,
Jahangirnagar University, Dhaka). Effect of
Physiological factors on the growth and sclerotia
29
Sci., 2006, 18 (1), 39-46.
Variable responses of two virulent isolates
(BTB115 and DK64) of Rhizoctonia solani were
observed with different physiological factors. No
mycelial growth was observed at 5°C and no
sclerotia were formed up to 10°C.The optimum
temperature for growth and sclerotia production
ranged from 25° to 30°C.Both the isolates could
grow at a wide range of pH.Higher growth and
higher number of sclerotia were recorded at pH 6
to 8.Vigorous mycelial growth and higher colony
density were observed in Czapeck's agar medium
in presence of N, P, K, Fe, Mg, and C. Growth of
R. solani was adversely affected in absence of C, N
and P in the medium while formation of sclerotia
was increased in absence of Mg. No sclerotia was
formed and colony density was thin in absence of
C-source. Manitol was found most suitable for
sclerotia production in both the isolates. Radial
mycelial growth was favoured by dextrose, glucose
and sucrose white none of the isolates could grow
at all when glycrol was used in the medium.
Peptone, NaNO 3 and NH 4NO 3 were found to be
good sources of nitrogen for mycelial growth and
sclerotia production in both the isolates tested.
107 RAHMAN, G.M.S. (Faculty of life and
Earth Science, National University, Gazipur);
HOSSAIN, M.I. ; AMEEN, M.U. (Dept. of
Zoology, Dhaka University, Dhaka) & ISLAM,
S.N. (Institute of Nutrition and Food Science,
Dhaka University, Dhaka). EFFICACY OF
AQUATIC PLANT EXTRACTS ON THE
LARVAE OF CULEX QUINGUEFASCIATUS
SAY (DIPTERA: CULICIDAE). Bang. J. Zool,.
2006, 34 (1), 1-5.
Various extracts of five different aquatic plants
namely. Lemna Perpusila, Spirodela polyrhiza,
Azolla pinnata. Chara fragilis and Utricularia minor
with methanol. chloroform and petroleum ether were
rd
th
tested against the late 3 or early 4 instar larvae of
Culex quinquefasciatus Say at room temperature in
the laboratory. The LC 50 values of the plant extracts
were in the following order of toxicity: Petroleum
ether extracts of S polyrhiza (2.50 ppt)> Petroleum
ether extracts of C. fragilis (3.22 ppt) > Chloroform
extracts of C. fragilis (3.84 ppt) > Chloroform
extracts of S. polyrhiza (5.53 ppt)> Petroleum ether