Ethylene stimulation of Hevea bark dryness and brown bast

De Fay E., . Ethylene stimulation of Hevea bark dryness and brown bast. pp. 201-209. ISSN 0127-7065

The tapping cut at the moment of tapping and the panel of control trees and trees treated intensively with ethylene were observed with the naked eye and under optical microscopy. Dry zones were larger in the stimulated trees; drying is linked to bark thickness and other modifications (soft bark hyperhydrated bark white lines on the bark necrotic areas and cracking at the surface). All these symptoms are the results of radial dilation of the outer phloem parenchyma caused by periclinal cell division which is the reaction of the surface tissue to hormone stimulation. Dryness is therefore accounted for by functional modifications of the bark rather than by the occasional presence of tyloses blocking a number of laticifers. Comparative histology of bark dryness following intensive ethylene treatment and bark affected by brown bast reveal different symptomatology. In addition intensive stimulation does not enhance the development of brown bast. Apart from dryness of hormonal origin a general tendency of Hevea to display temporary local dryness was observed; this is a seasonal reversible phenomenon which is not accompanied by any histological anomaly. Finally the complexity of the notion of bark dryness is stressed.

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Abstract

The tapping cut at the moment of tapping and the panel of control trees and trees treated intensively with ethylene were observed with the naked eye and under optical microscopy. Dry zones were larger in the stimulated trees; drying is linked to bark thickness and other modifications (soft bark hyperhydrated bark white lines on the bark necrotic areas and cracking at the surface). All these symptoms are the results of radial dilation of the outer phloem parenchyma caused by periclinal cell division which is the reaction of the surface tissue to hormone stimulation. Dryness is therefore accounted for by functional modifications of the bark rather than by the occasional presence of tyloses blocking a number of laticifers. Comparative histology of bark dryness following intensive ethylene treatment and bark affected by brown bast reveal different symptomatology. In addition intensive stimulation does not enhance the development of brown bast. Apart from dryness of hormonal origin a general tendency of Hevea to display temporary local dryness was observed; this is a seasonal reversible phenomenon which is not accompanied by any histological anomaly. Finally the complexity of the notion of bark dryness is stressed.

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Item Type:	Article
AGROVOC Term:	Hevea brasiliensis
AGROVOC Term:	Bark
AGROVOC Term:	Ethylene
AGROVOC Term:	Stimulation
AGROVOC Term:	Tapping
AGROVOC Term:	Plant tissues
AGROVOC Term:	Ethephon
AGROVOC Term:	Susceptibility to dryness
Depositing User:	Ms. Suzila Mohamad Kasim
Last Modified:	24 Apr 2025 06:28
URI:	http://webagris.upm.edu.my/id/eprint/23561

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