Variations in Axial and Ray Parenchyma Cells in Ten Hardwood Species Growing in Nigeria

Abstract

The optimal industrial utilisation of lesser used wood species globally require knowledge of the wood properties of the various species. One of the important properties of wood is the percentage composition of parenchyma cells. The distribution of axial and ray parenchyma cells of most of the indigenous hardwood species growing in Nigeria have not been studied.  This study centered on the distribution of axial and ray parenchyma cells of ten indigenous hardwood species in Nigeria. The mean lumen diameter vary from 11.0% in Anogeissus leiocarpus to 32.9% in Sterculia  setigera. The mean cell wall constituent of the axial parenchyma cells of the studied species also vary from 1.60% in Daniella oliverii to 12.5% in Mitragna inermis. The total axial parenchyma element of the wood species vary from 16.3% in Parinarium kerstingii to 45.4% in Sterculia  setigera. The ray parenchyma cells also vary within the species. The mean lumen content varies from 7.0% in Anogeissus leiocarpus to 15.8% in Daniella oliverii. The mean wall percentage of axial parenchyma cells also varies from 3.17% in Sterculia setigera to 15.29% in Anogeissus leiocarpus. The total axial parenchyma in the studied species vary from 12.37% in Sterculia setigera to 30% in Parinarium kerstingii.  The total parenchyma cells in all species vary from 41.6% in Prosopis africana to 59.32% in Detarium senegalense.  Available information  in literature showed that the higher the percentage of parenchyma cells the lower the quality of the wood species for pulp and paper production as parenchyma cells does not contribute significantly to strength development during pulp and paper making. In most cases, the parenchyma cells dissolve in the pulping chemicals. Thus, species such as Mitragyna inermis, Prosopis africana, Parinarium kerstingii and Anogeissus leiocarpus may perform better as wood for pulp and paper production on the basis of their low total parenchyma cell constituents. This may be due to the trade-off between higher fibre lumen constituents and parenchyma cells. This assumption may also be true for structural applications as parenchyma cells also influence wood density.

Keywords: Axial parenchyma, ray parenchyma, hardwood, lumen, wall