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Cold-induced photoinhibition, pigment chemistry, growth and nutrition of Eucalyptus nitens and E. globulus seedlings during establishment


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Close, Dugald Craig 2001 , 'Cold-induced photoinhibition, pigment chemistry, growth and nutrition of Eucalyptus nitens and E. globulus seedlings during establishment', PhD thesis, University of Tasmania.

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Australia is aiming to treble plantation wood production by 2020. Eucalyptus
globulus Labill. and E. nitens (Deane and Maidem) Maiden are the predominant
plantation species in southern Australia. This thesis describes physiological strategies
employed by these species in response to cold-induced photoinhibition during
seedling establishment. A series of experiments was conducted on seedlings prehardened
in the nursery. Their physiological and growth responses after planting in
the field was investigated.
A field trial was established at 350 m asl in early spring 1997. Severe cold-induced
photoinhibition caused photodamage which restricted growth of non-hardened E.
globulus. Artificial shading alleviated cold-induced photoinhibition and photodamage
in both E. globulus and E. nitens, and increased growth in E. globulus. Before
planting, nutrient-starved E. nitens were photoinhibited and had high anthocyanin
levels. Increased photoinhibition was not measured after planting because of
sustained xanthophyll activity and/or light attenuation by high anthocyanin levels. In
other treatments changes in anthocyanin levels were related to the severity of coldinduced
photoinhibition. Relative to E. nitens, growth of E. globulus was more affected by cold-induced
photoinhibition and photodamage. This was possibly due to inherently low levels of
carotenoids and lack of acclimation to cold temperatures. The effects of shading on
E. globulus and the absence of any effect of cold-hardening on E. nitens stresses the
importance of incident light and pigment levels in cold-induced photoinhibition. In a second field trial, an early winter planting of E. nitens was established at 700 m
asl in June 1998. Shading may have increased biomass production because of
alleviation of cold-induced photoinhibition. Growth in non-shaded than shaded
seedlings was greater overall due to higher biomass production in spring and summer.
Seedlings grew taller when shaded due to apical dominance. Fertilised seedlings
produced more biomass in the field than non-fertilised seedlings.
Low growth rates of E. nitens during winter at 700 m asl were associated with high
NPQ and sustained xanthophyll activity; photooxidation of chlorophylls, xanthophylls
and 13-carotene (which decreased light absorption), and increases in lutein and
neoxanthin (which indicated an antioxidant role). In general fertilised seedlings had
higher pigment levels which maintained higher levels of light utilisation and
dissipation. A controlled environment experiment which induced cold-induced
photoinhibition, confirmed that galloylglucoses and flavonoids can act as antioxidants
during seedling establishment. Sideroxylonals were also implicated in this role.
Anthocyanin kinetics during seedling establishment indicated absorption of irradiance
between 400 and 590 nm during periods of greatest cold-induced photoinhibition.
Chemical fractionation of leaf N and P indicated that E. globulus is more efficient at
acquiring N and P than E. nitens. After planting, re-translocation of stored foliar
protein N and inorganic P to roots occurred in both species. Greater amounts of retranslocation
in fertilised seedlings may contribute to their superior growth in the
Planting seedlings involves risk. Planting nutrient-starved seedlings may decrease the
risk of severe cold-induced photoinhibiiton and photodamage. However, this is at the
expense of optimal growth performance. Planting altitude and season will determine
whether fertilised or nutrient-starved seedlings should be planted.

Item Type: Thesis - PhD
Authors/Creators:Close, Dugald Craig
Keywords: Plants, Plants, Eucalyptus, Eucalyptus globulus
Copyright Holders: The Author
Copyright Information:

Copyright 2001 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:

Thesis (Ph.D.)--University of Tasmania, 2001. Includes bibliographical references

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