Comparative Analysis of the Agro-physiological Advantages of Upward and Downward Tapping in Different Rubber Clones of Hevea brasiliensis in Southwest Côte d'Ivoire

Abstract

The study examined the benefits of upward tapping over downward tapping for agro-physiological reasons in rubber clones GT 1 and PB 260 in Southwest Côte d'Ivoire. It was discovered that, in comparison to downward tapping, upward tapping increased rubber productivity by 35% for GT 1 and 37% for PB 260 clones. Regardless of the tapping direction, the examination of physiological parameters revealed that both clones had high dry rubber contents, indicating efficient latex regeneration during tapping. Regardless of the clone and tapping mechanism, the study also discovered that the physiological profiles of the trees and the dryness of the tapping panel were in good balance. The downward tapping on the virgin bark of the lower panel (BO) is immediately followed by the upward tapping on the virgin bark of the upper panel (HO), consecutively. To determine the agro-physiological advantages of one tapping over another, a study of the downward and upward tapping of the GT 1 and PB 260 clones of Hevea brasiliensis was carried out in southwestern Côte d'Ivoire. For this purpose, the rubber trees were tapped in a downward half-spiral (S/2) at the opening for nine consecutive years, followed by upward quarter-spiral tapping (S/4U) for four consecutive years. The agronomic parameters (rubber production and vegetative growth), tapping panel dryness and the latex micro-diagnosis, were evaluated. For the GT 1 clone, the transition from the downward tapping panels to the upward tapping panels resulted rubber productivity gain of 35%. Meanwhile for PB 260, rubber productivity gain was 37%. The isodiametric development of the tree trunk was found to decrease with increasing rubber production of a corresponding tapping panel, regardless of the clone and tapping direction. The combination of latex harvesting technologies and clones had no effect on the physiological profile of the trees or the dryness of the tapping panel. In summary, upward tapping yields higher productivity than downward tapping; nonetheless, the clone determines how much more rubber may be produced.