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Articles by Shahanara Begum
Total Records ( 4 ) for Shahanara Begum
  Shahanara Begum , Satoshi Nakaba , Md. Azharul Islam , Yusuke Yamagishi and Ryo Funada
  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.
  Shahanara Begum , Md. Azharul Islam and A.K.M. Azad-ud-doula Prodhan
  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.
  Shahanara Begum , Md. Azharul Islam and A.K.M. Azad-ud-doula Prodhan
  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.
  Shahanara Begum and A.K.M. Azad-ud-doula Prodhan
  Anatomical investigation has been made on the root of pigeonpea (Cajanus cajan (L.) Millsp.) at different stages of growth following the standard paraffin method of microtechnique. The root of pigeonpea is tetrarch with 4 strands of xylem and 4 strands of phloem. One strand of xylem alternates with one strand of phloem. The four opposite strands of primary xylem meet at the centre. Subsequently metaxylem forms near the centre on either side of the xylem strand. Ultimately the centre is filled up with big metaxylem vessels. The epidermis is single layered with root hairs and glandular trichomes. There are 8-13 layers of cortical cells in the root of pigeonpea. The cambium appears in the basal part of the root of 3-4 days old plant. Gradually it extends towards the root apex. The activity of cambium is similar to that of woody dicotyledonous herb. In the mature root, most of the vessels in the secondary xylem are solitary while the others are paired or multiple. The fibre cells in the phloem are arranged in groups. The fibre groups are radially arranged in such a way that the structure seems to be a pyramid. The epidermis is ruptured here and there, and the epidermal cells are disorganized due to the stress of secondary growth. Periderm is formed in the root one after another as the root increases in diameter.
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