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Aspects of leaf and extract production from Tasmannia lanceolata


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Read, CD 1995 , 'Aspects of leaf and extract production from Tasmannia lanceolata', PhD thesis, University of Tasmania.

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This thesis examines several aspects of the preparation, extraction and analysis of
solvent soluble compounds from leaf material of Tasmannia lanceolata and reports a
preliminary survey of extracts of some members of the natural population of the
species in Tasmania.
A major constituent of these extracts, polygodial, was shown to be stored within
specialised idioblastic structures scattered throughout the mesophyll, and
characterised by distinctive size and shape, and a thickened wall. The contents of
these cells were sampled directly, analysed and compared with the composition of
extracts derived from ground, dry whole leaf. This result was supported by
spectroscopic analysis of undisturbed oil cells in whole leaf tissue.
In a two year field trial, the progressive accumulation of a number of leaf extract
constituents (linalool, cubebene, caryophyllene, germacrene D, bicyclogermacrene,
cadina-1,4 - diene, aristolone and polygodial) during the growth flush was
followed by a slow decline during the subsequent dormant season. These results
were interpreted in relation to leaf dry matter accumulation, in order to propose a
harvest period within which leaf material will produce consistent composition of
Under four levels of irradiance in a growth cabinet experiment the plant exhibited
many characteristics of a 'shade' species, in particular, a limited ability to acclimate
to high light levels. Assimilation rates were highest at 150μmol m-2s-l while
elevated respiration rates and a reduced quantum yield occurred at a higher light
level. Maximum assimilation rates in leaves grown at 150μmol m-2s-l were
obtained at around 250μmol m-2s-l. Optimum net assimilation rate was obtained
from 18-25°C. The effect of level of irradiance on the proportion of extractable
compounds in the leaf, chlorophyll levels, specific leaf area, leaf thickness and
percentage dry matter in the leaf are reported and discussed in relation to a probable
production system in which the new canopy is largely removed at the end of each
growth cycle.
The ontogenetic patterns determining canopy architecture were observed in the
field, and used, with support from the results of a trial pruning of mature trees, to
discuss the likely outcome of various harvest methods. These results are combined
to suggest a production strategy for maximum yield of leaf extract of consistent
composition. The strategy proposes harvesting in late summer, after new leaf has
achieved full maturity and may enable full canopy recovery in the subsequent
growing season.

Item Type: Thesis - PhD
Authors/Creators:Read, CD
Keywords: Essences and essential oils, Essences and essential oils industry, Winteraceae
Copyright Holders: The Author
Copyright Information:

Copyright 1995 the author - The University is continuing to endeavour to trace the copyright owner(s) and in the meantime this item has been reproduced here in good faith. We would be pleased to hear from the copyright owner(s).

Additional Information:

Library has additional copy on microfiche. Thesis (Ph.D.)--University of Tasmania, 1997. Includes bibliographical references

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