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In rubber tree, Hevea brasiliensis, latex production is affected by tapping panel dryness characterized by non exudation of latex from the panel after tapping. The present study shows the sensitivity level of the more planted clones and the influence of climatic factors on the development of tapping panel dryness in Côte d'Ivoire. The lengths of sick panels were measured and the meteorological summaries carrying on the rainfall and the temperature have been made. Analysis of variance and comparison of the lengths of sick panel in relation to rainfall and temperature have been made. The results showed that Hevea brasiliensis clones have not the same sensitivity to tapping panel dryness. IRC A41, PB 217, AF 261 and RRIM 712 clones are little sensitive; IRCA 130, AVROS 2037, IRCA 209 and GT 1, are fairly sensitive whereas RRIC 100, IRCA 230, PB 254, PB 260 and PB 235 appear enough susceptible to tapping panel dryness. They also showed that the expression of tapping panel dryness varies seasonal way and is positively correlated to the water deficit and to the temperature. The less hot period from July to December corresponds to favorable period of rubber tree to better produce latex in stimulation conditions.

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Rubber tree rapid-metabolism clones generally have interesting agronomic and physiological characteristics. However, they are mostly sensitive to tapping panel dryness and breakage due to wind. This could be probably due to overexploitation caused by high tapping frequencies and/or high hormonal stimulation systems. To try solving this problem, a study was carried out over nine years using clones PB 260, PB 280 and PB 330 planted at a density of 510 plants/ha in southwestern Côte d'Ivoire. The experimental design was a randomized complete blocks with different latex harvesting technologies. The estimated parameters were rubber yield, radial vegetative growth, physiological profile and the profitability of applied latex harvesting technologies. Results indicated that non-stimulated combined with high tapping frequency latex harvesting system (d2 0/y) showed a level of rubber yield comparable to that of tapping frequencies d3 and d4 in all studied clones irrespective of the level of hormonal stimulation applied. Furthermore, the absence of hormonal stimulation had no negative influence on the vegetative growth and the physiological profile of rubber trees. Every two days (d2) tapping system without stimulation generated a profit margin statistically identical to that of low tapping frequencies (d4, d5 and d6) irrespective of the level of hormonal stimulation.