Destabilisation of lutoids in Hevea brasiliensis latex during early and late flow.

摘要

The commonly held supposition that lutoid damage (and, by inference, latex vessel plugging) in H. brasiliensis is most intense at the beginning of flow when the tree is tapped was re-examined. Damage to lutoids in latex collected at various intervals after tapping and just prior to flow cessation was assessed by the appearance of the bottom fraction of centrifuged latex and the bursting index of lutoids. Although increased bottom fraction damage was regularly observed in the initial latex fraction,the very extensive damage that has previously been reported to occur immediately after tapping was found to be uncommon in regularly tapped trees. Lutoid damage, as determined by the bursting index, fell briefly after the initial flow (1st min) and waslowest between the 4th and 15th minutes. Thereafter, the bursting index increased steadily until cessation of flow, by which time lutoid damage in the latex was most severe. Water potential increased as the latex became more dilute during the course of flow, but it was not clear to what extent lutoid damage could be attributed to the resulting osmotic shock. Based on the results of this study, a reassessment should be made of the common belief that the early flow latex is highly unstable and that latexthat is exuded during the later flow is more stable.