GROWTH OF SOUTHERN NAIAD (Najas guadalupensis) IN DIFFERENT SUBSTRATES AND FERTILIZATION LEVELS By HEATHER HASANDRAS A THESIS PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE UNIVERSITY OF FLORIDA 2016 © 2016 Heather Hasandras To my mother Ivy, whose life ended during my research. May I carry on, creating things in this world that will continue to live on past our years. ACKNOWLEDGMENTS I wish to thank my parents George and Ivy for raising a child that values education and encouraging me in my academic and personal pursuits. I thank my children, husband Denny and uncle John for attending my conferences and supporting me through this process of academic exploration. I thank my advisor Dr. Kimberly Moore for being an academic pillar during my years at University of Florida and for being that force that pushed me to get things completed. I thank my committee members Dr. Lyn Gettys for promoting the value of aquatic research and Dr. Vendrame for having oversight. I thank my lab group (Luci, Mun Wye, Tina, Nancy, Samar, Joanne, Sandy) and Andy during my studies for sharing friendship, good times, and guidance. You have illustrated that surrounding yourself with the right network of people does indeed help in life. 4 TABLE OF CONTENTS page ACKNOWLEDGMENTS .................................................................................................. 4 LIST OF TABLES ............................................................................................................ 6 LIST OF FIGURES .......................................................................................................... 7 LIST OF ABBREVIATIONS ............................................................................................. 8 ABSTRACT ..................................................................................................................... 9 CHAPTER 1 INTRODUCTION .................................................................................................... 11 2 LITERATURE REVIEW .......................................................................................... 13 Aquatic Plant Growth .............................................................................................. 14 Invasive Aquatic Plant Control ................................................................................ 17 Invasive Aquatic Plants ........................................................................................... 20 Southern Naiad ....................................................................................................... 26 3 GROWTH OF NAIAD (Najas guadalupensis) AND HYDRILLA (Hydrilla verticillata) USING CONTROLLED RELEASE FERTILIZER Materials and Methods............................................................................................ 29 Results and Discussion........................................................................................... 30 4 GROWTH OF NAIAD IN SUBSTRATES WITH VARYING PERCENTAGES OF SAND AND CONTROLLED-RELEASE FERTILIZER ............................................. 36 Materials and Methods............................................................................................ 37 Results and Discussion........................................................................................... 39 5 CONCLUSIONS ..................................................................................................... 48 LIST OF REFERENCE .................................................................................................. 50 BIOGRAPHICAL SKETCH ............................................................................................ 55 5 LIST OF TABLES Table page 3-1 Southern naiad (Najas guadalupensis) and hydrilla (Hydrilla verticillata) shoot and root dry weight of plants grown in sand and fertilized with 0, 1, 2, or 4 g of Osmocote 15N-4.05P- 9.96K.. ........................................................................ 33 4-1 Naiad (Najas guadalupensis) shoot and root dry weight of plants grown in 100:0 sand:peat, 75:25 sand:peat, 50:50 sand:peat, 25:75 sand:peat or 0:100 sand:peat (by volume). ............................................................................. 42 4-2 Naiad (Najas guadalupensis) shoot and root dry weight of plants fertilized with 0, 1, 2, or 4 g of Osmocote 15N-4.05P- 9.96K. ........................................... 43 4-3 Shoot concentrations of ammonia (NH3-N), phosphate (PO3-P) and potassium (K) in naiad (Najas guadalupensis) shoots harvested from the experiment 2 conducted in spring 2015. ............................................................. 44 4-4 Water sample pH, electrical conductivity (EC), nitrate (NO3-N), phosphate (PO3-P) and potassium (K) of naiad (Najas guadalupensis) plants from the experiment 2 conducted fertilized with 0, 1, 2, or 4 g per pot of Osmocote 15N-4.05P- 9.96K. .............................................................................................. 45 6 LIST OF FIGURES Figure page 3-1 This is an example of the 18 gallon plastic containers (mesocosms) and experimental layout. Each mesocosm contained three pots of either hydrilla or naiad. ............................................................................................................. 34 3-2 During experiment 1, a parapoynx moth (Parapoynx diminutalis) was found at week 7 of the experiment................................................................................ 35 4-1 Naiad (Najas guadalupensis) shoot dry weight of plants fertilized with 0, 1, 2, or 4 g of Osmocote 15N-4.05P- 9.96K and grown in 100:0, 75:25, 50:50, 25:75, or 0:100 sand:peat substrate (by volume) ............................................... 46 4-2 Final substrate electrical conductivity for plants fertilized with 0, 1, 2, or 4 g of Osmocote 15N-4.05P- 9.96K and grown in 100:0, 75:25, 50:50, 25:75,or 0:100 sand:peat substrate (by volume). ............................................................ 47 7 LIST OF ABBREVIATIONS C Celsius CRF Controlled Release Fertilizer EC Electrical conductivity F Farenheit g Grams g/kg Grams per kilogram K Potassium mg/L Milligrams per Liter N Nitrogen nm Nanometer NH4-N Ammonia NO3-N Nitrate P Phosphorus PO3-P Phosphate RH Relative humidity µg/L Micrograms per Liter W·m2 Watts per meter square 8 Abstract of Thesis Presented to the Graduate School of the University of Florida in Partial Fulfillment of the Requirements for The Degree of Master of Science GROWTH OF SOUTHERN NAIAD (Najas guadalupensis) IN DIFFERENT SUBSTRATES AND FERTILIZATION LEVELS By Heather Hasandras May 2016 Chair: Kimberly Moore Major: Horticultural Sciences The native aquatic plant southern naiad (Najas guadalupensis) is often confused with the invasive weed hydrilla (Hydrilla verticillata). A lot of information has been published on the growth of hydrilla but few studies have investigated the growth of naiad. In experiment 1, we compared the growth of naiad and hydrilla plants fertilized with 0, 1, 2, or 4 grams controlled release fertilizer (CRF) (Osmocote 15N-4.05P-9.96K) layered under the surface per kilogram of the sand prior to planting. We had three mesocosms per fertilizer rate with 3 containers of naiad and 3 containers of hydrilla in each mesocosm. Mesocosms were randomly placed in a greenhouse and filled with water to create a submersed growing environment. The experiment ran for eight weeks in spring 2014 and was repeated in summer 2014. Data from summer 2014 showed that naiad shoot dry weight was greater with 2 g CRF/kg sand than 0 or 4 g CRF/kg sand. Hydrilla shoot dry weight was greater with 4 g CRF/kg sand than 0 g. In the Experiment 2, we investigated the growth of naiad grown in 100:0, 75:25, 50:50, 25:75, and 0:100 sand:peat substrate fertilized with 0, 1, 2, or 4 g of CRF/kg substrate. We had three mesocosms per fertilizer rate with 5 pots (1 for each substrate). The experiment ran for 9 8 weeks in August 2014, and was repeated in June 2015. Naiad shoot dry weights were greater in 100:0 than 0:100 sand:peat substrates. Naiad root dry weight was greater in 50:50 than 0:100 sand:peat. The 0:100 substrate had higher substrate electrical conductivity (EC) levels than the other substrates. Naiad shoot dry weights were also greater with 1 to 2 g of CRF/kg substrate than 0 or 4 g CRF/kg substrate. There was no difference in tissue ammonia nitrogen (NH4-N) levels among the different fertilizer rates but phosphate (PO3-P) and potassium (K) were highest in naiad shoots fertilized with 1 and 2 g CRF/kg substrate than 0 or 4 g CRF/kg. The water analysis showed no differences in pH, EC, or K due to fertilizer rates but both nitrate nitrogen (NO3-N) and PO3-P were higher in mesocosms with the 4 g CRF/kg substrate than the other rates. Substrate EC concentrations also were highest in all substrates fertilized with 4 g CRF/kg substrate. Based on these results we would recommend growing naiad in substrates with 50% or more sand and fertilized with 1 to 2 g CRF/kg substrate. 10 CHAPTER 1 INTRODUCTION In the United States $100 million each year is invested for control of aquatic invasive weeds (Office of Technology Assessment [OTA], 1993). The most damage from invasive aquatic weeds occurs to our natural ecosystems in the Southern and Western portions of the country (Pimental et al., 2005). Invasive plants alter the natural interactions in an aquatic habitat. Invasive plants are often responsible for reduction in oxygen levels, increases in water