Abstract

Stimulation of Hevea brasiliensis is a common practice in rubber estates. The chemicals commonly used are formulations of 2-chloroethylphosphonic acid (ethephon). Low frequency of tapping must be accompanied by use of yield stimulants in order to enjoy the economics of low tapping frequency. It is thus necessary to evaluate the effects of the available yield stimulants on Hevea in order to better formulate exploitation systems. Two formulations of 2-chloroethylphos-phonic acid, under the trade name Hevetex 5% PA and Ehtrel^® were used to stimulate two clones. Hevetex5% PA was investigated using agronomic parameters, and latex diagnosis technique to determine its efficiency as a yield stimulant, its ability to induce tree dryness, activation of tree metabolism and ability to sustain rubber yields. Hevetex 5% PA is a good yield stimulant and has good sustaining properties demonstrated by the level of its physiological properties (such as sugar and thiols) which are comparable to those of Ethrel^®. The use of these stimulants led to an increase in rubber yield. The physiological parameters and yield varied with season.

Key words: Stimulation, Hevea brasiliensis, rubber, 2-chloroethylphosphonic acid, physiological parameters.