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| Articles
by
Shahanara Begum |
Total Records (
3 ) for
Shahanara Begum |
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Shahanara Begum
,
Satoshi Nakaba
,
Md. Azharul Islam
,
Yusuke Yamagishi
and
Ryo Funada
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Effects of low temperature on cambial cells induced by localized heating in Cryptomeria japonica and Abies firma were investigated during winter dormancy in January-February. Localized heating induced cambial reactivation in the stems earlier than natural cambial reactivation. In heated Cryptomeria japonica and Abies firma stems, cambial reactivation occurred after 6 and 2 days of heating, on 14 January 2007 and 15 January 2010, respectively. We stopped the electric heating system just after cambial reactivation in stems. When we stopped the heating system, the minimum atmospheric temperature was about 0°C. After cambial reactivation, due to rapid decrease in temperature, cell contents of cambium became coagulated but nucleus was present in ray cambial cells. After one month, the shrunk cambium produced new deformed tracheids with abnormal cell shape. The results suggest that rapid decrease in temperature just after cambial reactivation might induce temporary damage of cambium that produces deformed tracheids indicating that cambium and its derivatives can response directly to changes in temperature which provides a useful experimental model system for studies of cambial biology and xylogenesis. |
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Shahanara Begum
,
Md. Azharul Islam
and
A.K.M. Azad-ud-doula Prodhan
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Anatomical investigation has been made on the stem of
pigeonpea (Cajanas cajan (L.) Millsp.) at different stages of growth
following the standard paraffin method of microtechnique. The vascular
bundle of the stem are collateral and arranged in a ring. The cambium
initiates in the primary vascular bundle between xylem and phloem at the
basal part of the stem of 3 days old plant. After the formation of fascicular
cambium it gives rise to secondary xylem adaxially and secondary phloem
abaxially. Most of the vessel members are solitary and few are paired
while others are multiple. The solitary vessel members are more in mature
stem as compared to that of the younger stem. The well developed periderm
was found in mature stem. The pith resembles a typical dicotyledonous
stem. |
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Shahanara Begum
,
Md. Azharul Islam
and
A.K.M. Azad-ud-doula Prodhan
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The anatomical investigation of the rachis has been made on the basis of flower removal. Two different types of rachis have been investigated. One type of rachis is normal (control) which develops naturally up to maturity and another type is deflowered (treated) where flowers and buds have been removed from the basal 3 nodes and then allows the rachis to develop naturally up to maturity. After removal of flowers and buds, pods are found to be set in 4-6 nodes of the same rachis. The internal structure of rachis is more or less similar to that of the stem. Epidermis bears multicellular hairs and glandular trichomes. The vascular tissue decreases gradually from base upward. The vascular tissue become highly developed in the deflowered rachis. The cambium is highly active on its adaxial side and produces a large amount of secondary xylem adaxially and well developed sieve tube elements abaxially. Some large vessels are formed in the abaxial region of the xylem. In the middle and upper parts of the deflowered rachis, the radial dimension of xylem is several times higher than the corresponding part of the normal rachis. The vascular tissue is poorly developed in the apical part of the normal rachis. The xylem is mainly composed of fibre cells with ray parenchyma which is uniseriate or multiseriate. Pericycle is discontinuous at the basal part and gradually it forms a more or less continuous ring towards the apical part around the vascular cylinder. Tanniniferous cells are more in the normal rachis compared to that of the deflowered rachis. |
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