Chez l'hévéa, la plupart des clones sélectionnés à bas âge, à partir de la combinaison des quatre paramètres physiologiques du latex (Pi, Sac, Exs et R-SH) qui expliquent au mieux la productivité adulte, n'expriment pas l'augmentation de production attendue à l'âge adulte. L'efficacité de prédiction des rendements de ces paramètres pris individuellement a été étudiée, chez les arbres adultes. Des corrélations ont été établies entre la production et les paramètres physiologiques mesurés à un stade précoce de la sélection (CCPE). Des corrélations ont également été établies entre ces mêmes paramètres physiologiques mesurés en CCPE et la production estimée en fin de sélection (CCGE). Le saccharose et le phosphore inorganique ont présenté les meilleures tendances à prédire le potentiel de production à l'âge adulte.

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In order to test the agronomic performance of the newly developed clones, a Large-Scale Clone Trial (LSCT) comprising Hevea brasiliensis clones GT 1, IRCA 202, IRCA 331, IRCA 707, PB 280 and PB 310 was established in southwestern Côte d'Ivoire. They were planted in completely randomized blocks with six clone treatments and four replications of 112 trees per clone. The measured parameters included isodiametric growth of the trunk, rubber yield, trees stand, latex physiological parameters and sensitivity to tapping panel dryness (TPD). Collected data was analyzed using Statistica 7.0 statistical software. After ten years of downward tapping and four years of upward tapping, clone IRCA 331 showed significantly higher rubber productivity than all other clones. Its productivity gain, relative to the reference control GT 1, was 63% in downward tapping and 80% in upward tapping. Despite its high level of productivity, the annual rate of isodiametric growth of clone IRCA 331 tree trunks (2.56 cm/year) remained statistically equivalent to that of clone GT 1 (2.62 cm/year) at latex harvesting stage. In addition, the physiological profile of clone IRCA 331 was good and similar to that of the control. Clones IRCA 331, GT1 and PB 280 got the lowest sensitivity to TPD. However, only clones GT1 and IRCA 331 maintained a good stand of tappable trees throughout the experimental period. This experiment highlighted the agronomic performance of the clone IRCA331 and allowed to put it in class 1. Clone IRCA 331 can therefore be used as a clone of first choice to improve national productivity.

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