Kouadio Dian, Maturin Koffi Okoma, Edmond Kouablan Koffi, Désiré N’da Pokou, Modeste Kouassi Kan, Gislaine Zaka Kouadjo, Nazaire Koffi II Kouassi, Abdourahamane Sangare and Samuel OBOUAYEBA
Laboratoire Central de Biotechnologie, Centre National de Recherche Agronomique Abidjan, Côte d’Ivoire
Station de recherche de Bimbresso, Centre National de Recherche Agronomique Abidjan, Côte d’Ivoire
CORAF, Dakar, Sénégal
Key words: Ethephon stimulation frequency, Downward tapping, Upward tapping, Production potential, PB 260 clone of Hevea brasiliensis.
The present study evaluates the impact of different stimulation frequencies of Ethephon in downward tapping on the production potential of trees in upward tapping of the clone PB 260 of Hevea brasiliensis. Six parameters are measured: production per tree, tapping panel dryness percentage and four latex biochemical parameters which were dry rubber content, inorganic phosphorus, sugar and thiols. The results show that in downward tapping, generally, the biochemical parameters level is inversely proportional to the stimulation frequency during years 9 and 10. Regarding the production, beyond four stimulations per year, it is inversely proportional to the stimulation frequency. When the trees are tapped upward with a four stimulation uniform per year, the production continues to be low according to the preceding frequency stimulation in downward tapping beyond four stimulations per year. However, the factors which caused this decrease don’t seem to be the same in the first and the second years of upward tapping. In the first year of upward tapping, according to the evolution of the biochemical parameters, the decrease in production is linked to physiological tiredness due to the stimulation in downward tapping. On the other hand, in the second year, it is a phenomenon of familiarization to Ethephon which could explain the decrease in production on treatments which received more than four stimulations per year in downward tapping. In second year of upward tapping, the trees need more than four times per year Ethephon stimulations to reach their production potential.