Photoinhibition of photosynthesis at low temperatures was investigated in two species of subalpine eucalypt, Eucalypts nitens (Deane and Maiden) Maiden and E. pauciflora Sieb. ex Spreng. Imposition of an artificial cold-hardening treatment increased the frost tolerance of leaf tissue and increased tolerance to excess light. Cold-hardened seedlings of both species had a higher photosynthetic capacity than non-hardened seedlings at 6 and 16°C and lower levels of non-photochemical quenching (NPQ) at 20 and 5°C. Furthermore, hardened seedlings had faster rates of NPQ development at 5 and -3.5°C. An increase in minimal fluorescence, which indicates slowly reversible photoinhibition, was evident in all seedlings at -1.5 and -3.5°C but was less pronounced in hardened seedlings, with a threefold faster rate of development of NPQ, at -3.5°C than nonhardened seedlings. Hardened seedlings also recovered faster from photoinhibition at -3.5°C. Thus cold hardening increased tolerance to high light in these species. Differences between E. nitens and E. pauciflora in their response to excess light were small and significant only at -3.5°C. Faster recovery from photoinhibition of E. pauciflora was consistent with its occurrence in colder habitats than E. nitens.

Item Type:	Refereed Article
Research Division:	Biological Sciences
Research Group:	Plant Biology
Research Field:	Plant Physiology
Objective Division:	Expanding Knowledge
Objective Group:	Expanding Knowledge
Objective Field:	Expanding Knowledge in the Environmental Sciences
Author:	Warren, CR (Mr Charles Robert Warren)
Author:	Hovenden, MJ (Associate Professor Mark Hovenden)
Author:	Davidson, NJ (Dr Neil Davidson)
Author:	Beadle, CL (Dr Christopher Beadle)
ID Code:	15094
Year Published:	1998
Web of Science® Times Cited:	19
Deposited By:	Plant Science
Deposited On:	1998-08-01
Last Modified:	2011-08-10
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