EVALUATIONS OF VESSEL ELEMENTS AND RAYS IN THE TRUNK OF THEOBROMA CACAO

Abstract

The morphology of the vessel elements and rays in the trunk of a fruiting tree ofTheobroma cacao were carried out with the aid of light microscope. The vesselelements were short and narrow being less than 350μm and occurred in solitaryand multiple forms. The ray tissues were both homogeneous and heterogeneous indistribution. Vessel and ray morphology such as length, diameter and height wereevaluated, fifty vessels and rays were measured and thereafter the data weresubjected to ANOVA and Duncan Multiple Range Test (D.M.R.T). The totalaverage 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 toppositions of the trunk were 422.31 ± 152.20, 349.23 ± 163.23 and 250.53 ± 189.39respectively. The diameters (μm) of the vessels on the other hand, were averages of86.34 ± 35.96, 79.24 ± 32.06 and 70.28 ± 27.96 for the base, middle and top positionsof the trunk respectively. The total height (μm) and diameter (μm) of the rays wereaverages of 0.79 ± 0.47 and 74.85 ± 36.68 respectively. From the axial direction, thepool means of the height of rays were 1.09 ± 0.33, 0.78 ± 0.44 and 0.52 ± 0.45 for thebase, middle and top regions of the trunk respectively. At P ≤ 0.05, the length anddiameter of vessels decreased significantly from the base to the top of the trunk.Similarly, the heights and diameters of rays in the trunk decreased significantlyfrom base to top. The physiological advantages of the types of vessel and rayswere discussed vis- a- vis the previous assertions of authors within the presentcontext