The Effects of Water Flow, pH and Nutrition on the Growth of the Native Aquatic Plant, Aponogeton elongatus Mark Norman Crossley B. Hort. Sc. Massey University A thesis submitted for the degree of Master of Philosophy at the University of Queensland, Gatton. School of Agronomy and Horticulture Date : 3/11/02 STATEMENT OF ORIGINALITY “I hereby declare that the work presented in this thesis has not been previously submitted for a degree at any university. To the best of my knowledge and belief, this thesis contains material that is original and has not been previously published or written by another author except where due reference is made.” ……………………………… Mark Norman Crossley i ACKNOWLEDGMENTS The author would like to thank his supervisors, Richard Williams, Bill Dennison and Alan Wearing for their general assistance, encouragement, guidance, constructive criticisms and editorial comment. Research grants from the Flora Foundation, University of Queensland new staff scheme and Gatton College provided for much of the infrastructure and some of the working expenses. Thanks to the Qld Dept of Conservation and DPI forestry for the plant collection permits and access to the collection site. Thanks also to Alan Lisle for his statistical help, David Pilon, who designed and built the pH controller, provided the computer, wrote the software for the controller and helped set up and debug the control system and Victor Robertson, John Bertrum, Kath Raymont, and Robyn Collinge for their technical assistance. Thanks also to Greg O’Sullivan who isolated the fungus Pythium fromA. elongatus leaf and stem lesions and to the Marine Botany Group postgraduates for their feedback and assistance with the fluorescence measurements. Finally, the author would like to thank his wife for her considerable patience and encouragement, and for minor editing of thesis. ii LIST OF ABBREVIATIONS AND SYMBOLS CH COOH aceticacid 3 adapt adaptor ADP adenosinediphosphate ATP adenosinetriphosphate AC alternating current NH + ammoniumion 4 A Amp ANOVA analysis of variance et. al. and others (Latin: et alabi) AE anion exchange mechanism (cid:167) approximate aq. aqueous B boron BRI bridge rectifier BSP British Standard Pipe Ca calcium CaCO calciumcarbonate 3 CO carbon dioxide 2 H CO carbonic acid 2 3 CA carbonic anhydrase C capacitor Cu copper CAM crassulacean acid metabolism DH degree of hardness (German) oC degrees centigrade or Celsius (cid:303)13C delta 13carbon D diode DC or dc direct current DIC dissolved inorganic carbon dry wt. dry weight or biomass iii EC electricalconductivity e- electron ETR electron transport rates (cid:1179) equilibrium Figs. figures eg. for example (Latin: exempi gratia) FAA formalin/acetic acid/alcohol C-4 four carbon eg oxaloacetic acid g gas or gram GMA glycol methacrylate > greater than GND ground h hours H+ hydrogenion ICP inductivelycoupledplasma I/O input/output board ID internal diameter Fe iron K Potassium or kilo eg 1000 Ohm LSD least significant difference LSM least squares means < less than LED lightemitting diode r linear correlation coefficient r2 linear correlation coefficient squared L litre Log logarithm LS longitudinalsection Mg magnesium MDH malate dehydrogenase Mn manganese m meter µF microFarad iv µM microMolar µmol micromoles µScm-1 microSiemens per centimetre mL millilitre mg milligram mm millimetres nF nanoFarads nm nanometres NAD nicotinamide adenine dinucleotide NADH nicotinamide adenine dinucleotide reduced N nitrogen or Normality (chemistry: g equivalents L-1) n number of samples O/C opencollector O oxygen 2 ppm parts per million (mg/Kg) % percentage PC personalcomputer PEP carboxylase phosphoenolpyruvatecarboxylase P phosphorusorprobability PAR photosynthetically active radiation ± plus or minus pwr. power pH power of hydrogen PK pyruvatekinase QLD Queensland RLC rapid light curves Eh redox potential REG regulator R relay R or r resistor RuBP ribulose 1, 5-bisphosphate s second Na sodium v cm2 square centimetres SD standarddeviation SE standarderror SAM submerged aquatic macrophytes S sulphur ie. that is (Latin: id est) C-3 threecarbons egphosphoglyceric acid TDS total dissolved salts TS Transverse section Tr treatment USA United States of America V or v volts Zn Zinc vi ABSTRACT The Australian native freshwater macrophyte, Aponogeton elongatus, is a decorative aquarium plant but little is known about the ecophysiology of its growth and environment. Formerly, plants were collected from the wild to supply the pet/aquarium retail industry in Australia and overseas. Conservation measures introduced by Australian State Governments now restrict this practice. To achieve an understanding of how environmental factors can be manipulated for optimum growth in cultivation, the long-term effects of stirred water, nutrition and water pH on A. elongatus growth were examined in two studies. The plants were grown in sand filled pots in aquaria, under fluorescent lights (PAR; 100µmol m-2s-1) in temperatures from 22-24°C. Slow release fertiliser (Osmocote PlusR) placed in the sand substrate supplied nutrition. A four-fold increase in plant growth in two months was found in stirred water with a pH level between 6.5 and 7.8 and fertile sediment. This macrophyte was also found to depend on its roots for nutrient uptake and it was the combined effect of nutrient availability and stirring that produced the strongest growth. The supply of dissolved inorganic carbon was the main factor in the plant response to stirred water, presumably due to the reduction in boundary layer resistance around the leaves. Dissolved free CO was more readily 2 assimilated than bicarbonate based on the strong growth response in water of pH 6.5 to 7.8 and strong correlation between the concentration of dissolved free CO and 2 plant growth. It is apparent that the manipulation of nutrient level, dissolved free CO and pH 2 greatly influenced the growth of A elongatus in stirred water. These findings would benefit the commercial cultivation of this plant and give some insight as to the extent ofA. elongatus adaptation to an aquatic environment. vii PUBLICATIONS Crossley, M. N. and R. R. Williams. (2001). Cultivation of the freshwater aquatic plantAponogeton elongatus. (Poster and abstract) 20th International Eucarpia Symposium, Section Ornamentals, Belgium, July 2001. Crossley M. N., W C. Dennison, R. R. Williams and A. H. Wearing. (2002). The interaction of water flow and nutrients on aquatic plant growth. Hydrobiologia (Accepted). viii TABLE OF CONTENTS Page STATEMENT OF ORIGINALITY ........................................................................i ACKNOWLEDGMENTS .......................................................................................ii LIST OF ABBREVIATIONS AND SYMBOLS ..................................................iii ABSTRACT ...........................................................................................................vii PUBLICATIONS ................................................................................................viii TABLE OF CONTENTS .....................................................................................ix LIST OF APPENDICES .....................................................................................xiii LIST OF FIGURES .............................................................................................xiv LIST OF TABLES ............................................................................................xviii LIST OF PLATES ...............................................................................................xix CHAPTER 1 GENERAL INTRODUCTION .............................................1 1.1 Background to Research ...............................................................................1 1.2 Significance of this Thesis ............................................................................7 1.3 General Objectives and Thesis Structure ......................................................8 CHAPTER 2 LITERATURE REVIEW ......................................................9 2.1 Introduction ...................................................................................................9 2.2 Aquatic Sediment ........................................................................................10 2.3 The Water Environment above the Sediment .............................................11 2.3.1 Light ..............................................................................................11 2.3.2 Irradiance (Intensity) ....................................................................11 2.3.3 Light Quality (Spectral Distribution) ...........................................11 2.3.4 Temperature .................................................................................12 2.4 Chemical Properties of Water .....................................................................13 2.4.1 pH .................................................................................................13 2.4.2 Alkalinity ......................................................................................14 2.4.3 Water Hardness ............................................................................14 ix