Kenaf-based composite posts as alternative supports for black pepper (Piper nigrum L.)

Black pepper is a perennial climber and the provision of a supporting post is important for the successful establishment of black pepper planting in the producing countries. With the high cost of establishing black pepper planting using the traditional Belian post, there is a need to develop alternative posts for its sustainability. The study was carried out to evaluate the use of Kenaf composite posts for black pepper planting compared to the commonly used Belian post as supporting material. Three types of Kenaf composite posts, namely, Kenaf Extrusion, Kenaf Pultrusion and Kenafkrete posts, together with mechanically controlled fibre-glass posts, were investigated for black pepper planting. The epiphytical response of black pepper plant, accelerated laboratory decay test, leaf temperature, leaf-to-air vapour pressure deficit and the leaf gas exchange rate were the parameters assessed in this study to indicate the suitability of the composite post for black pepper growing. The trial plot was established at thoroughly exposed conditions to determine the sustainability of Kenaf composite posts at open field conditions. The study demonstrated that adventitious roots of black pepper plants were able to bind on all types of support except the Kenafkrete post, which showed a low number of cling roots. On durability observation, the Kenaf Extrusion post showed severe bending and was intolerant to field weather conditions, whereas the Kenafkrete post showed moderate level of cracks on the post. The laboratory decay test indicated that Kenaf composite posts were highly resistant to wood decay fungi and performed better than Belian post. It was discovered that Kenaf Extrusion contributed to an adverse microclimate environment for the growth of black pepper by showing significantly (p<0.05) higher leaf temperature and leaf-to-air VPD. Leaf photosynthesis rates (A) and leaf stomatal conductance (gs) of black pepper supported by Belian, Kenaf Pultrusion, Kenafkrete and fibre-glass were comparatively (p<0.05) higher than recorded for Kenaf Extrusion. The results of this study implied that among the supports studied, Kenaf Pultrusion and fibre-glass posts showed positive results as good alternative supports to the currently used Belian post for black pepper planting.