Agronomic Performance of Hevea brasiliensis Muell. Arg. Clone IRCA 331 Grown in Southwestern Côte d'Ivoire

Abstract

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.

Dynamic analysis of Tapping Panel Dryness in Hevea brasiliensis reveals new insights on this physiological syndrome affecting latex production

“…The first reason is the low natural occurrence of TPD in plantations for standard recommended harvesting systems (about 1% per year). However, a certain level of clonal variation of TPD rate was determined in large-scale clone trials for six rubber clones ( Elabo et al., 2019 ). The second reason is related to the high environmental influence.…”