Plant anatomy as a tool for evaluating the effect of different levels of nitrogen, plant population density, row spacing and irrigation on kenaf (Hibiscus cannabinus) fibre development

Abstract

Kenaf (Hibiscus cannabinus) provides high-quality fibre that is used in papermaking, building materials and absorbents. The study aims were to conduct a proper anatomical study of fibre development in kenaf stems, and to investigate if the number of fibre wedges, fibre rings (layers) and fibre bundles can be used as a tool to determine fibre development response to different agronomic practices. The practices evaluated included different nitrogen levels (0, 50, 100 and 150 kg N ha−1) under both rainfed and irrigated conditions, as well as different combinations of plant population densities (300 000, 400 000, 500 000 and 600 000 plants ha−1) and row spacing (0.17, 0.34 and 0.50 m) under rainfed conditions. In most cases N, water and plant population density were the principal factors affecting the number of fibre rings and fibre bundles, but not the number of fibre wedges. Higher levels of N and more water increased the number of fibre rings and fibre bundles, whereas at higher plant population densities, these decreased. No clear trends were observed with regards to row spacing. The results of this study suggested that under local conditions, 150 kg N ha−1 applied in two splits, 300 000 plants ha−1 and 0.50 m row spacing was the optimal combination of agronomic practices in terms of fibre development per plant. This paper gives a more complete explanation of fibre development in kenaf and shows how plant anatomy can be used as a tool to assess fibre development.