New Zealand Journal of Botany abstracts
Deficit irrigation effects on photosynthesis and the xanthophyll
cycle in the tropical tree species Acacia auriculiformis in
North Australia
Li-Xia Liu
Shou-Min Xu
School of Life Sciences
Key Laboratory for Vegetation Ecology of Ministry of Education
Northeast Normal University
Changchun 130024, China
K. C. Woo
School of Biological Sciences
Charles Darwin University
Darwin, NT 0909, Australia
Abstract The effect of water stress was examined
in a clone of Acacia auriculiformis grown in irrigated and
unirrigated sites during the wet and dry seasons in Darwin, northern
Australia. During the dry season unirrigated plants had very low leaf
water potential and thick leaf cuticles compared with irrigated plants.
The plants were photoinhibited under these conditions and they showed
greatly reduced Fv/Fm ratio and photosynthetic activity. Chlorophyll
and leaf soluble protein contents decreased but carotenoid and
xanthophyll, especially zeaxanthin, contents increased greatly compared
with irrigated plants. Unirrigated plants showed large diurnal changes
in photosynthesis and zeaxanthin and violaxanthin contents.
Photosynthetic activity was 3–7-fold less and zeaxanthin level
20–50-fold higher than the values determined in the wet season or under
irrigated conditions. The high level of xanthophyll cycling observed in
the unirrigated or dry season plants was presumably associated with the
dissipation of excess light energy and serves to protect the
photosynthetic apparatus from photoinhibition.
Keywords Acacia auriculiformis; irrigation;
photosynthesis; xanthophyll cycle
B04012; Received 30 March 2004; accepted 24 June 2004; Online
publication date 9 December 2004
New Zealand Journal of Botany, 2004, Vol. 42: 949–957
0028–825X/04/4205–0949 © The Royal Society of New Zealand 2004
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