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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.

Potato extract (PE), corn extract (CE) and papaya extract (PAE) significantly enhanced plantlet regeneration from PLBs (protocorm-like bodies) when 50 mL L - 1 of an extract was supplemented to the New Phalaenopsis (NP) medium containing sucrose. Among the treatments, CE 50 mL L - 1 induced the highest rate (66.63%) of plantlet regeneration from PLBs. Organic extracts of potato, corn and papaya at 50-100 mL L - 1 in NP medium also enhanced the subsequent growth of mini-plantlets. However, a higher level (200 mL L - 1 ) of extract in the medium inhibited the growth of the plantlets. Among these extracts, PE at 100 mL L - 1 showed the optimum effect on the acceleration of shoot growth while CE at the same concentration was optimum for root growth.

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.

Potato extract (PE), corn extract (CE) and papaya extract (PAE) at concentrations of 25, 50 and 100 mL L - 1 enhanced callus growth on New Phalaenopsis (NP) medium containing sucrose. Among the various concentrations, 100mL L - 1 PE or PAE and 200 mL L - 1 CE significantly promoted callus growth compared to the control. Regeneration of protocorm-like bodies (PLBs) from calli was optimum when NP medium (sometimes referred to as BM) was supplemented with 100 mL L - 1 CE, followed by PE and PAE at the same concentration. Most plantlets also regenerated from PLBs with one 100 mL L - 1 CE.

The ultrastructure of the fibre wall in Fraxinus mandshurica Rupr. var. japonica Maxim. was investigated by electron microscopy. The trees had been inclined artificially at an angle of 30° to the vertical at the beginning of the initiation of cambial growth in early spring. The secondary walls of tension wood fibres were of the outer (S1) layer and gelatinous (G) layer type. The microfibrils in the gelatinous (G) layer were oriented as a steep Z-helix relative to the fibre axis with a deviation that ranged from 0° to 25° but was mainly between 5° and 10°. The cross-sectional surface of tension wood fibres revealed the relatively strong attachment of the G-layer to the S1 layer. The G-layer stained weakly with potassium permanganate. The S1 layer of tension wood fibres stained less strongly than that of the normal and opposite wood fibres. These results indicate that the tension wood in F. mandshurica var. japonica is not typical and is somewhat anomalous. The secondary walls of normal and opposite wood fibres were composed of two layers, S1 and S2, and lacked an S3 layer. Microfibrils in the S3 layer of juvenile stems were extremely variable in orientation and were sparsely distributed without forming a layer. By contrast, a very thin S3 layer was present in the wood fibres of mature stems. The variations in the formation of the S3 layer in the fibre walls were probably due to the differences in the cambial age of the stems of F. mandshurica Rupr. var. japonica.

Estimation of leaf number currently held on the plant and degree of leaf sheding occurred was carried out in two Cassava ( Manihot esculenta ) morphotypes (Philippine and Nagra) at Mymensingh (24°75´N 90°50´E). Four linear regression Models were developed for estimating leaf number (LN) from length (L) of mainstem (MS) and primary branch (PB) and they were LN MS = -6.89 + 1.05L MS (Model # 1) and LN PB = -5.116 + 1.033LPB (Model # 2) for Philippine; and LN MS = -4.041 + 0.73L MS (Model # 3) and LNPB = -1.597 + 0.707L PB (Model # 4) for Nagra morphotype. New leaf number produced in the mainstem (LN MS ) and primary branch (LN PB ), total leaf number in the mainstem (TL MS ) and primary branch (TL PB ) of each morphotype were also counted for leaf abscission (LAB) prediction model and the results showed that the regression models of leaf abscission in the primary branch (LAB PB ) from new leaf in the primary branch (LN PB ) was effective (LAB PB = - 0.521 + 0.525LN PB ) (Model # 6). These regression Models showed linear relationships when actual leaf number was plotted against predicted leaf number and that this confirmed accuracy of the developed Models. Moreover, Models selection indices had high predictability (high R 2 ) with minimum error (low error mean square error and percentage deviation). The selected Models appeared accurate and rapid, but can be used for estimation of leaf production in Philippine and Nagra morphotypes of Cassava. Keywords: Manihot esculenta ; Regression; Leaf production; Leaf abscission DOI: http://dx.doi.org/10.3329/jbau.v9i1.8743 JBAU 2011; 9(1): 49-54