UC Riverside UC Riverside Electronic Theses and Dissertations
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UC Riverside UC Riverside Electronic Theses and Dissertations Title Field Evaluation of Ion Uptake of Avocado Rootstocks as Affected by Salinity Permalink https://escholarship.org/uc/item/1vc893mb Author Celis, Nydia Publication Date 2016 Peer reviewed|Thesis/dissertation eScholarship.org Powered by the California Digital Library University of California UNIVERSITY OF CALIFORNIA RIVERSIDE Field Evaluation of Ion Uptake of Avocado Rootstocks as Affected by Salinity A Thesis submitted in partial satisfaction of the requirements for the degree of Master of Science in Environmental Sciences by Nydia Celis June 2016 Thesis Committee: Dr. Laosheng Wu, Chairperson Dr. Donald L. Suarez Dr. David E. Crowley Copyright by Nydia Celis 2016 The Thesis of Nydia Celis is approved: Committee Chairperson University of California, Riverside ACKNOWLEDGMENTS I would like to express my sincerest gratitude to my major advisor, Dr. Laosheng Wu, for accepting me into the program and for his advice and guidance throughout this process. I am especially grateful to Dr. Donald Suarez for his guidance, support, expertise, and patience. I also want to thank him for allowing me to use the facilities at the U.S. Salinity Laboratory to conduct the soil and plant analysis and for training me on various instruments. I would also like to thank Dr. David Crowley for serving in my thesis committee and giving me valuable recommendations and suggestions. Special thanks to Dr. Peggy Mauk for her collaboration on the funded research project. I would also like to thank all the staff who helped keep the project running Rui Li, Bruce Martin, Charles Farrar, Mahlet Desta, and Priya Kumar. I would also like to thank the Avocado Commission for funding this project. To Nancy Phu for sharing this journey with me and for being supportive and helpful along the way. To my sisters Monica and Nathalie for always believing in me and cheering me on. iv DEDICATION I would like to dedicate this thesis to my husband, Rene, for his love and support and to my parents Ernesto and Juana who at an early age instilled in me the value of education and for their unconditional love and encouragement. I would also like to dedicate this to God without whom none of this would have been possible. v ABSTRACT OF THE THESIS Field Evaluation of Ion Uptake of Avocado Rootstocks as Affected by Salinity by Nydia Celis Master of Science, Graduate Program in Environmental Sciences University of California, Riverside, June 2016 Dr. Laosheng Wu, Chairperson With potable water becoming a scarce resource in semi-arid regions, we must evaluate the potential to use degraded water for irrigation without reducing yield. Avocado is one of the most salt sensitive crops, and one of the highest value per acre. The objectives of this experiment were to screen avocado rootstocks for salinity tolerance, study the effect of sodium and chloride on growth and yield, quantify the salt distribution in the root zone, and relate the soil salinity to leaf ion composition and in turn to salt tolerance. A field experiment was conducted to evaluate the salt tolerance of 13 different avocado rootstocks grafted onto Hass scion. The experiment consists of 252 trees arranged in a randomized block design with four rows per block and four replications. The experimental plot is arranged in rows which alternate between those irrigated with a fresh water control, and a salt treatment with electrical conductivities of 0.5 dS m -1 and 1.5 dS -1 -1 -1 m and chloride levels of 0.73 mmol c L and 4.94 mmol c L respectively. vi The salt movement during the salinization process was recorded by selected intensive soil sampling, and soil resistivity profiling using the SuperSting ® 56 electrode resistivity imaging system. We collected soil samples and leaves from the plot and analyzed them for major ions. The rootstocks R0.06, R0.07, PP14, and R0.17 were found to have high concentrations of chloride and sodium in the leaves and therefore the least salt tolerant having 100 % mortality in the salt treated rows after being irrigated for 23 months. The rootstocks that had low concentrations of sodium and chloride ions in the fully expanded leaves were R0.05, PP40, R0.18 and DUSA, which were also the rootstocks whose growth and yield was minimally affected also exhibiting the highest yield, highest trunk diameter and highest survival percentage. vii TABLE OF CONTENTS Chapter Page ACKNOWLEDGMENTS . .iv DEDICATION . v ABSTRACT . vi TABLE OF CONTENTS . viii LIST OF TABLES . x LIST OF FIGURES . .xi CHAPTER I: INTRODUCTION . 1 CHAPTER II: BACKGROUNG AND LITERATURE REVIEW . 3 Avocado. .3 Salt Tolerance. 5 Avocado Salt Tolerance. .6 Plant Ion Composition . 8 Toxicity. 10 Sodium Toxicity. .11 Chloride Toxicity. .11 Salinity Problem. .12 Electrical Tomography . 14 2 Dimensional Surveys . .14 Advantages and Disadvantages of the Different Arrays. 16 Electrical Resistivity and Soil Properties. .17 CHAPTER III: METHODOLOGY . 21 Experimental Design . .21 Irrigation . .23 Electrical Resistivity . .24 Soil . 25 1:1 Soil Extracts. .26 Soil Texture . .27 Soil Electrical Conductivity . 29 pH Measurements . .29 Chloride Titrator. 30 viii Chloride in Soil Extracts. 31 Leaf Collection . 32 Chloride in Plant Samples. 33 Wet Digestion . .34 Statistics. .35 CHAPTER IV: RESULTS . 36 Irrigation Water . .36 Soil Sampling Analysis . .40 Soil Temperature. 44 Electrical Resistivity . .45 Plant Ion Analysis . .47 Rootstock Survival . 60 Plant Ion Interaction. .62 Avocado Yield . 64 Plant Growth Parameters. .71 CHAPTER V: SUMMARY. .75 CHAPTER VI: CONCLUSION. 78 REFERENCES. 80 ix LIST OF TABLES Table Page Table 1: Chloride Tolerance of fruit crop cultivars and rootstock . 7 Table 2: Electrical conductivity of saturation extracts at which yield reductions become significant . .. 8 Table 3: Irrigation Water Composition. 23 Table 4: Calculated leaching fractions based on the chloride and the electrical conductivity of the 1:1 extracts . .44 Table 5: Average leaf ion composition collected October 2013. 49 Table 6: Average leaf ion composition in control rows collected in October 2014. 52 Table 7: Average leaf ion composition in salt rows collected in October 2014. 52 Table 8: Average leaf ion composition in control rows collected in October 2015. 55 Table 9: Average leaf ion composition in salt rows collected in October 2015. 56 Table 10: Potassium-Sodium ratio for each rootstock in the salt treated rows . .62 x LIST OF FIGURES Figure Page Figure 1: California Avocado Acreage Summary by County in 2014. .4 -1 Figure 2: Dusa in control row EC w = 0.5 dS m . .36 -1 Figure 3: Dusa in a salt treated row EC w = 1.5 dS m . .36 -1 Figure 4: R0.07 in control row EC w.