Authors: Edward W J Tsen Joseph A M Holtum
Publish Date: 2012/03/23
Volume: 113, Issue: 1-3, Pages: 311-320
Abstract
This study demonstrates unequivocally the presence of crassulacean acid metabolism CAM in a species of the Rubiaceae the fourth largest angiosperm plant family The tropical Australian endemic epiphytic antplant Myrmecodia beccarii Hookf exhibits net CO2 uptake in the dark and a concomitant accumulation of titratable acidity in plants in the field and in cultivation Plants growing near Cardwell in a north Queensland coastal seasonally dry forest of Melaleuca viridiflora Sol ex Gaertn accumulated ~50 of their 24 h carbon gain in the dark during the warm wet season During the transition from the wet season to the dry season 24 h carbon gain was reduced whilst the proportion of carbon accumulated during the dark increased By mid dry season many plants exhibited zero net carbon uptake over 24 h but CO2 uptake in the dark was observed in some plants following localised rainfall In a shadehouse experiment droughted plants in which CO2 uptake in the light was absent and dark CO2 uptake was reduced were able to return to relatively high rates of CO2 uptake in the light and dark within 12 h of rewateringEWJT was supported by an Internal Research Allocation grant from the School of Marine and Tropical Biology James Cook University We acknowledge invaluable assistance in the field by Dr AR Field Melanie Adams Leesa Baker Cassandra Denne David Duchene Trisha Knavel Katja Reichel Marine Sonie and Saul Walker Particular thanks to Janelle Price who held the umbrella at 2 am during gasexchange measurements in the wet season JAMH acknowledges with gratitude 36 years of mentorship by Professor CB Osmond who courageously agreed to be his PhD supervisor in 1976
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