Effect of hormonal stimulation regime on agro-physiological parameters of rubber clone IRCA317 in south-west Côte d’Ivoire

Hormonal stimulation is a key practice for optimising natural production in rubber (Hevea brasiliensis) trees. However, its effectiveness depends closely on the physiological characteristics of each clone, particularly age and metabolism. This study sought to determine the hormonal stimulation regime best suited to the IRCA317 clone grown in south-west Côte d’Ivoire. Treatments included moderate (4/y) and intensive (10/y) stimulation regimes on yield,physiological parameters and sensitivity to tapping panel dryness of the IRCA317 rubber clone. This was compared to those IRCA41, PB260, PB217 and GT1 clones. The experiment was laid out in a randomised complete block design, with five clones and four replications. The results revealed that, in downward tapping, the IRCA317 clone generated a production gains of 6 and 19% compared with the GT1 clone under moderate and intensive conditions, respectively. In the upward tapping, the gains were 29 and 19%, respectively. However, the stimulation regime did not influence the physiological parameters of the clones significantly (P>0.05). On the other hand, the intensification of hormonal stimulation, generally led to a decrease in sucrose and thiol group contents in the latex of the clones. Regarding sensitivity to tapping panel dryness, the intensive regime led to a significant increase in TPD in the IRCA317 clone, reaching 12.8 % in downward tapping and 24.4 % in upward tapping. These results suggest that the moderate regime (4 applications/year) is a near optimal strategy for ensuring sustainable productivity and preserving the physiological integrity of clone IRCA317.