Evaluations of Vessel Elements and Rays in the Trunk of The Obroma CACAO

The morphology of the vessel elements and rays in the trunk of a fruiting tree of Theobroma cacao were carried out with the aid of light microscope. The vessel elements were short and narrow being less than 350μm and occurred in solitary and multiple forms. The ray tissues were both homogeneous and heterogeneous in distribution. Vessel and ray morphology such as length, diameter and height were evaluated, fifty vessels and rays were measured and thereafter the data were subjected to ANOVA and Duncan Multiple Range Test (D.M.R.T). The total average length (μm) and diameter of the vessels were 340.69 ± 182.27 and 78.62 ± 32.66 respectively. The pool means of vessel lengths (μm) at base, middle and top positions of the trunk were 422.31 ± 152.20, 349.23 ± 163.23 and 250.53 ± 189.39 respectively. The diameters (μm) of the vessels on the other hand, were averages of 86.34 ± 35.96, 79.24 ± 32.06 and 70.28 ± 27.96 for the base, middle and top positions of the trunk respectively. The total height (μm) and diameter (μm) of the rays were averages of 0.79 ± 0.47 and 74.85 ± 36.68 respectively. From the axial direction, the pool means of the height of rays were 1.09 ± 0.33, 0.78 ± 0.44 and 0.52 ± 0.45 for the base, middle and top regions of the trunk respectively. At P. 0.05, the length and diameter of vessels decreased significantly from the base to the top of the trunk. Similarly, the heights and diameters of rays in the trunk decreased significantly from base to top. The physiological advantages of the types of vessel and rays were discussed vis- a- vis the previous assertions of authors within the present context.