Relationship between cyanogenesis and latex stability on tapping panel dryness in rubber trunk girth

Abstract

The presence of high cyanogenic glycoside concentrations may predispose plant to the tapping panel dryness (TPD). This study aimed to verify the involvement of cyanogenesis in the reduction of latex stability and in the establishment of TPD. The following parameters were evaluated in rubber tree trunk bark: concentration of cyanogenic glycosides with determination of cyanogenic potential (HCNp) and latex stability with lutoid bursting index (LBI). The study of the relationship between cyanogenesis and TPD was performed by semiquantitative comparison of hydrogen cyanide (HCN) gas released from the trunk bark under the following conditions: without (0%) and with (100%) TPD. The positive correlations between HCNp values and LBI indicate that cyanogenic glycosides present in the bark reduce latex stability, resulting in low yield due to the short duration of flow during tapping. The largest amount of HCN released by trunk bark tissues when the plant exhibits TPD symptoms strengthens the evidence of the involvement of this compound in the establishment of this condition.

Keywords:

• Hevea spp.
• lutoid bursting index
• cyanogenic potential
• β-glucosidase

Acknowledgments

The authors are thankful to Sérgio de Araújo Silva and Francisco Exigidras Leite Magalhães, from Embrapa Amazônia Ocidental, for their support in sample collection and analyses.