Improvement of Productivity of the Moderate Metabolism Clone GT 1 of Hevea Brasiliensis Muell. Arg. by Early Upward Tapping in Côte d'Ivoire

Abstract

The quest for greater return on investment at short time is a recurring concern of the rubber industry. Early reverse tapping could be an option to this concern. It is therefore to verify this hypothesis that five different stages of initiation of upward tapping, 6th, 7th, 8th, 9th year and the control in 10th year, with application of 2.5 and 5% ethephon was conducted for eight years in the South-East (Bettie) and the Centre-West (Gagnoa) of Cote d'Ivoire. Irrespective of the ethephon concentration used, average yield obtained from upward tapping at 6th year was 3012 ± 516 kg ha-1 y-1 against 2528 kg ha-1 y-1 in the control, where controlled upward tapping started at 10th year with a productivity gain of 19%. The mean annual increase in circumference in the upward tapped trees at 6th year, was 3.02 ± 0.18 cm y-1 and statistically higher than that of the control treatment (2.40 cm y-1). Physiological profiles improved during the experiment, regardless of site and of periods of upward tapping. Generally, the sensitivity to panel dryness in the control is more pronounced than that of early upward tapping. Our results suggest very early upward tapping at 6th year after the 5 years of downward tapping, is the best period to harvest latex from the high tapping panel.