Dr. James Syvertsen

Dr. James Syvertsen

  Professor Emeritus
  Horticultural Science
  Phone: 863.956.8677
  Email: jmsn@ufl.edu
  Fax: 863.956.4631



Ph.D. 1977, Biology. Physiological plant ecology of desert species. New Mexico State University, Las Cruces, NM.
B.A. 1970, Biology and M.A. 1973, Plant Ecology, California State Univ., Fullerton, CA.


Environmental Stress Physiology of Citrus


2014. ISHS Lifetime Achievement Award for “Outstanding Contributions to Research and Education in Fruit Crop Physiology” presented by The Environmental Physiology of Fruit Crops Working Group of the ISHS. March 2014.

2013. Fulbright Research Scholarship Award to research flooding tolerance in citrus rootstocks in Salto, Uruguay and to increase mutual understanding between the people of the United States and Uruguay.

2013.  Elected an Honorary Member of the Florida State Horticultural Society for special meritorious service to FSHS and to the advancement of horticulture in Florida. Honorary Membership is one of the greatest honors the Society can bestow.

2008-2011. University of Florida Research Foundation Professorship awarded from the UF Vice President for Research for “Distinguished Research Performance, Publications, Service and Commitment”.


Research interests: Integration of citrus stress physiology. Effects of light, temperature, mechanical harvesting, drought, salinity, pests and nutrient stress on water, carbon and nutrient budgets of citrus. Response measurements include: Photosynthesis, root conductivity, leaf water relations, plant carbohydrates, canopy development, fruit yield, fruit shape and quality. Resource use efficiency, N leaching loses.

Refereed Publications (since 2008)


Syvertsen, J.P., Garcia-Sanchez, F. 2014 Multiple abiotic stresses occurring with salinity stress in citrus. Environ. Exp. Bot. 103: 128-137. PDF


Cimò, Giuseppe, Pedro Gonzalez Blanco, Wije Bandaranayake, Ed Etxeberria, Riccardo Lo Bianco and James Syvertsen. 2013. Carbohydrate and Nutritional Responses to Stem Girdling and Drought Stress with Respect to Understanding HLB Symptoms in Citrus. HortScience 48: 920-928. PDF

Caballero, F., F. García-Sánchez, V. Gimeno, J. P. Syvertsen, V. Martínez and F. Rubio. 2013High affinity potassium uptake in seedlings of two citrus rootstocks Carrizo citrange (Citrus sinensis [L.] Osb. × Poncirus trifoliata [L.] Raf.) and Cleopatra mandarin (Citrus reshni Hort. ex Tanaka) Aust. J. Crop Sci. 7(5):538-542. PDF


Gonzalez, P., James P. Syvertsen and Ed Etxeberria. 2012. Sodium distribution in salt-stressed citrus rootstock seedlings. HortScience 47: 1504-1511. PDF

Gimeno V., J.P. Syvertsen, I. Simón, M. Nieves, L. Díaz-López, V. Martínez, F. Garcia-Sanchez. 2012. Physiological and morphological responses to flooding with fresh or saline water in Jatropha Curcas. Environmental and Experimental Botany 78: 47-55. PDF

Gimeno V, J.P. Syvertsen, I. Simon, V. Martinez, Jose M. Camara-Zapata, Manuel Nieves, F. Garcia-Sanchez. 2012. Interstock of Valencia orange affects the flooding tolerance in Verna lemon trees. HortScience 47:403-409. PDF

Zambrosi, F.C. B., D. Mattos Jr., R.M. Boaretto, J.A. Quaggio, T. Muraoka and J.P. Syvertsen. 2012. Contribution of phosphorus (32P) absorption and remobilization for Citrus growth. Plant & Soil 355:353–362. PDF

Grosser, J.W.,  Ahmad A. Omar, Julie A. Gmitter and J. P. Syvertsen. 2012. Salinity Tolerance of ‘Valencia’ Orange Trees on Allotetraploid Rootstocks. Proc. Fla. State Hort. Soc. 125:50–55. (Refereed Proceedings) PDF


Zambrosi, F. D. DeMattos Jr. and J.P. Syvertsen. 2011. Plant growth, leaf photosynthesis, and nutrient-use efficiency of citrus rootstocks decrease with phosphite supply. J. Plant Nutr. Soil Sci. 174: 487-495. PDF

Melgar, J.C, and J.P. Syvertsen.  2011. Oleocellosis Injury of Fruitlets Caused by Late-Season Mechanical Harvesting of ‘Valencia’ Orange Trees After Different Irrigation Treatments Does Not Affect Internal Fruit Quality. HortSci 46(3):1-3. PDF


Melgar, J.C, J. Dunlop, L.G. Albrigo and J.P. Syvertsen.  2010. Winter drought stress can delay flowering and avoid immature fruit loss during late season mechanical harvesting of 'Valencia' oranges. HortScience 45: 271-276. PDF

Syvertsen, J.P ., J.C. Melgar and F. García-Sánchez. 2010. Salinity Tolerance and Leaf Water Use Efficiency in Citrus. JASHS 135: 33-39. PDF

Gimeno, V., J.P. Syvertsen, F. Rubio, V. Martínez and F. García-Sánchez. 2010. Growth and mineral nutrition are affected by substrate type and salt stress in seedlings of two contrasting Citrus rootstocks. J. Pl Nutr. 33: 1435–1447. PDF

Melgar, J.C., A.W. Schumann and J.P. Syvertsen. 2010. Fertigation frequency affects growth and water and nitrogen use efficiencies of Swingle citrumelo citrus rootstock seedlings. HortScience 45:1255–1259. PDF

Melgar, J.C., J. Dunlop and J.P. Syvertsen. 2010. Growth and Physiological Responses of the Citrus Rootstock Swingle Citrumelo Seedlings to Partial Rootzone Drying and Regulated Deficit Irrigation.  J of Agr Sci  148: 593-602. PDF


Gimeno, V., J. P. Syvertsen, M. Nieves, I. Simón, V. Martínez and F. García-Sánchez.2009. Orange varieties as interstocks increase salt tolerance of lemon trees. J. Hort. Sci. Biotech. 84: 625-631. PDF

Gimeno, V., J.P. Syvertsen, M. Nieves, I. Simón, V. Martínez and F. García-Sánchez. 2009. Additional nitrogen fertilization affects salt tolerance of lemon trees on different rootstocks. Sciencia Horticulturae. 121: 298–305. PDF

García-Sánchez F. and J.P. Syvertsen. 2009. Substrate Type and Salinity Affect Growth Allocation, Tissue Ion Concentrations, and Physiological Responses of Carrizo Citrange Seedlings. HortSci. 44: 1432-1437. PDF


Li, Kuo-Tan, J. Burns, and J. P. Syvertsen. 2008. Recovery from phytotoxicity after foliar application of fruit-loosening abscission compounds to citrus. JASHS 133:535–541. PDF

Melgar, J.C., J.P. Syvertsen, and F. García-Sánchez. 2008. Can elevated CO2 improve the salt tolerance in ‘Koroneiki’ and ‘Picual’ olive tree cuttings? J Plant Physiology 165: 631-640.  PDF

Melgar, J.C, J.P. Syvertsen, V. Martínez and F. García-Sánchez. 2008. Leaf gas exchange, water relations, nutrient content and growth in citrus and olive seedlings under salinity. Biol. Plantarum 52 (2): 385-390.  PDF

Orbovic, Vladimir, J.P. Syvertsen, D. Bright, D. L. Van Clief & J.H. Graham. 2008. Growth of Citrus seedlings and their susceptibility to Phytophthora root rot are affected by PO^3 and PO^4 sources of phosphorus. J. Plant Nutrition 31: 774 - 787. PDF

Non-Refereed Publications (since 2008)

Syvertsen, J.P. and Wije Bandaranayake. 2012. Salinity Tolerance of ‘Hamlin’ Orange Trees on the Hybrid Rootstocks US-897 and x639 Is Greater than of Trees on Cleopatra Mandarin. Proc. Fla. State Hort. Soc. 125:56–60. PDF

Ebel, R.C. K. Morgan, P.Newman, J. K. Burns, and J. Syvertsen. 2008. Effects of Short-Term Drought Stress of 'Hamlin' and 'Valencia' Trees and CMNP Application on Fruit Detachment Force, Fruit Drop, and Fruit Quality. Proc. Fla. State Hort. Soc. 121: 65-68. 

Schumann, A.W., J.P. Syvertsen, and J.H. Graham. 2008. Microbial Soil Amendments do Little to Improve Citrus Tree Performance in Florida Soils. Proc. FSHS 121: 134-139.