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Seasonal salinity remains a problem which limits Experiments were carried out with five mungbean
possible growth of crops all the year round. varieties with/without Bradyrhizobium at
Manpura posses some peculiar environmental Bangladesh Agricultural University Farm during
characteristics. This island constitutes a part of the kharif-I 2001 and kharif-I 2002 seasons to find out
active Ganges delta and is gradually changing by the time of nodule initiation, nodulation pattern
sediment accretion and erosion every year. As a and their size distribution. Five mungbean
result its exact area estimation is difficult. Natural varieties, viz., Barimung-2, Barimung-4,
environment is terribly fragile as the banks of this Barimung-5, Binamung-2 and Barisal local, and
island are still unstable and erosion is a constant rhizobial inoculum (Bradyrhizobium strain BAUR-
threat that may finally result in the obliteration of 604) were used in this experiment. Each variety
the island. Climatic type is humid tropical was tested with/without inoculation. For recording
monsoon with sometimes heavy torrential nodule initiation date, five randomly selected
downpour. The island is flat and its elevation plants from each plot were uprooted at alternate
varies from place to place from the mean sea level days starting from 7 days after sowing (DAS). For
and a large part of the island is flooded twice daily recording nodule size, all the nodules were
during the high tides in the monsoon season. If collected from roots. Nodules were grouped by
global warming causes the sea level to rise, as grading them on the basis of their size in diameters
some people predict, the Manpura island will go (<2.0, 2.1-4.0 and >4.0 mm). The nodules were
under water possibly. Nevertheless, around 50,000 first visible at 9 DAS, when only a few small
people have already settled there with threat in nodules were observed. The number of nodules
mind. Rice cultivation is the main occupation of increased progressively with the increasing growth
the islanders with fishing and cattle/buffalo period and reached the peak at 42 DAS (i.e., at
farming as secondary activities. The settled parts of 50% flowering stage). The number of nodules (2-4
the islands are protected from saline water mm) started to decline after 42 DAS sharply and in
intrusion by dykes. Plantation mangrove forest case of <2 mm size nodules, the declining was
covers a sizeable part of the island that protects it noticeable after 56 DAS, while the bigger nodules
from the hazards of tropical cyclonic storms and were increased up to 63 DAS. No effective nodule
lethal tidal water surges. In spite of the existing of any size was found at 77 DAS. The results
ecological hazards the island acts as a source of suggested that nodule initiation in the roots of
hope for many poor and landless people of mungbean varieties started at 9 days of sowing
Bangladesh especially those who were made seeds (DAS), reached the peak at 42 DAS and
destitute by river bank erosion in the coastal belt. thereafter started reducing in numbers until 70
DAS due to spontaneous degeneration.
343 BHIYAN, M.A.H. (Soil Science Division,
BARI, Gazipur); MIAN, M.H.; (Hajee 344 GANI, M.N.; ALIM, M.A.; ALAM,
Mohammad Danesh Science & Technology A.K.M.M.; SAMAD, M.A.; KHANDKER, S.
University, Dinajpur); ISLAM, M.S. (BARI, (Bangladesh Jute Research Institute, Dhaka) &
Gazipur) & ISLAM, M.R. (Dept. of Soil Science, RAHMAN, S.M.B. (Dept. of Biochemistry and
Bangladesh Agricultural University, Mymensingh). Molecular Biology, Jahangirnagar University,
Detecting Time of Nodule Initiation in Mungbean. Bang. Savar, Dhaka). Effect of cow dung and chemical
J. Microbiol., 2005, 22 (1), 20-28. fertilizer on growth, yield and quality of jute
(Chorchorus olitorius L.). Bang. J. Life Sci., 2006,

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