Relationship between tapping intensity and tapping panel dryness susceptibility of some clones of #Hevea brasiliensis# in Southwestern Côte

摘要

It is well known that the productivity and the susceptibility to the tapping panel dryness (TPD) of Hevea brasiliensis are determined by the intrinsic feature of each clone but also by the tapping system. Thus, in order to establish the tapping system that minimizes the TDP occurrence an experiment was carried out in Côte d'Ivoire with four high yielding clones including, PB 235, PB 255, IRCA 18 and IRCA 111. Five tapping systems (d2 6d/7 0/y, d3 6d/7 4/y, d4 6d/7 6/y, d5 6d/7 8/y, d6 6d/7 10/y) were applied to these clones, corresponding to a range of 100 % to 30 % of tapping intensities. The results show that the occurrence of TPD is closely related to the tapping intensity and the tapping system which consists in tapping twice per week with one day rest (S/2 d3 6d/7 4/y), was found to be the best tapping system. A quadratic relation was found between the rate of the TPD and the tapping intensity. Thus the clones IRCA 18 and IRCA 111, like PB 235 and PB 255, belong to the active metabolism clones. These clones also showed their adherence to the group of high rubber producer clones. This experiment also gave further evidence that the production of a tree for the tapping strongly depends on the intensity of tapping. It has also indicated that the intensity of tapping governed the tapping panel dryness rate among the clones having active metabolism, such as IRCA 18, IRCA 111, PB 235 and PB 255. (Résumé d'auteur)