Tapping panel dryness (TPD) syndrome is a serious problem affecting the productivity of Hevea plantations. There is complete shut down of rubber biosynthesis in the laticiferous cells of·fully dry trees. The biochemical composition of the live laticiferous tissues of TPD affected and healthy Hevea trees was compared in the present study. The TPD affected laticiferous tissues contained comparatively higher levels of sugars, phenols and soluble proteins than healthy tissues. Also there was significantly higher activity of peroxidase and lower activity of polyphenol oxidase in the affected than in the healthy tissues. The results showed that lack of availability of sucrose was not the cause for TPD. The high peroxidase activity and the accumulation of phenols in the laticiferous tissue indicate possible oxidative stress in the TPD affected bark tissues. It appears that oxidative damage of laticiferous vessels may be responsible for the complete shut down of the rubber biosynthetic machinery, possibly by altering the energy metabolism in fully dry trees.
Biochemical composition, Hevea brasiliensis, Oxidative stress, Tapping panel dryness
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