Faculty

TED DEJONG Vice Chair, Outreach and Extension, Department of Plant Sciences (1994 - present) 3037 Wickson Hall (530) 752-1843 tmdejong@ucdavis.edu

Ph.D.  (1977) Botany, University of California, Davis.  Membership in Graduate Groups:  Horticulture & Agronomy, Plant Biology

The research in my laboratory is primarily field-oriented and directed toward gaining a better understanding of the environmental physiology of tree crops. We are interested in elucidating the factors that determine, enhance, or limit both the photosynthetic efficiency of fruit trees and the allocation of assimilates toward various fruit tree components. On the basis of this research we are attempting to develop improved, physiologically sound, horticultural practices that increase production efficiency of tree crops.  The primary approach that we have been using in these studies is the development of a computer model that simulates seasonal tree carbon assimilation and partitioning on a daily basis.  This model is based on simple concepts of carbon supply and demand for maintenance, growth and storage functions of various organs.  The concepts developed in the model permit new approaches to studying the integrated effects of environmental stresses such as temperature, water and nutrients on canopy photosynthesis and partitioning of assimilates to vegetative vs. reproductive plant parts.  Some of the horticultural systems that we are currently evaluating are: optimization of fruit thinning practices, adjustments in fertilizer and irrigation application rates and timing, and rootstock selection of tree size control. The crops that we are most closely associated with are peaches, nectarines, plums, and prunes.

Selected Publications

116.*    Basile, B., M.J. Mariscal, K.R. Day, R.S. Johnson, and T.M. DeJong.  2002.  Japanese plum (Prunus salicina L.) fruit growth:  seasonal pattern of source/sink limitations.  Journal American Pomological Society 56(2):86-93.

 
119.*   Rosati, A. and T.M. DeJong. 2003. Estimating photosynthetic radiation use efficiency using incident light and photosynthesis of individual leaves. Annals of Botany 91:869-877.

120.*   Marsal, J., B. Basile, L. Solari, and T.M. DeJong. 2003. Influence of branch autonomy on fruit, scaffold, trunk and root growth during Stage III of peach fruit development. Tree Physiology 23:313-323.

121.*   Berman, M.E. and T.M. DeJong. 2003. Seasonal patterns of vegetative growth and competition with reproductive sinks in peach (Prunus persica). Journal of Horticultural Science & Biotechnology 78(3):303-309.

122.*   Basile, B., J. Marsal, and T.M. DeJong. 2003. Daily shoot extension growth of peach trees growing on rootstocks that reduce scion growth is related to daily dynamics of stem water potential. Tree Physiology 23:695-704.

123.*   Weibel, A., R.S. Johnson, and T.M. DeJong. 2003. Comparative vegetative growth responses of two peach cultivars grown on size-controlling versus standard rootstocks. J. Amer Soc. Hort. Sci. 128(4):463-471.  

124.*   Basile, B., J. Marsal, L.I. Solari, M.T. Tyree, D.R. Bryla, and T.M. DeJong. 2003. Hydraulic conductance of peach trees grafted on rootstocks with differing size-controlling potentials. Journal of horticultural Science & Biotechnology 78(5):768-774.

#128.*  Lampinen, B.D., K.A. Shackel, S.M. Southwick, W.H. Olson, and T.M. DeJong. 2004. Leaf and canopy photosynthetic responses of French prune (Prunus domestica L. ‘French’) to stem water potential based deficit irrigation.  J. Hort. Sci. and Biotechnology 79:638-644.

#130.*  Day, K.R., T.M. DeJong, and R.S. Johnson. 2005. Orchard-system configurations increase efficiency, improve profits in peaches and nectarines.  California Agriculture 59:75-79.

#134.*  DeJong, T.M., R.S. Johnson, J.F. Doyle, and D. Ramming.  2005.  Research yields size-controlling rootstocks for peach production.  California Agriculture 59:80-83.

#135*.  Allen, M.T., P. Prusinkiewicz, and T.M. DeJong. 2005.  Using L-systems for modeling source-     sink interactions, architecture and physiology of growing trees: the L-PEACH model.  New Phytologist 166:869-888.

#136.*  DeBuse, C.J., D.V. Shaw, and T.M. DeJong.  2005.  Response to inbreeding of seedling traits in a Prunus domestica L. breeding population.  J. Amer. Soc. Hort. Sci. 130:904-911.

#137.*  Gordon, D., C. Damiano, and T. M. DeJong. 2006.  Preformation in vegetative buds of Prunus     persica: factors influencing number of leaf primordial in overwintering buds.  Tree Physiology 26:537-544.

#138.*  Pernice, F., L. Solari, and T.M. DeJong.  2006.  Comparison of growth potentials of epicormic shoots of nectarine trees grown on size-controlling and vigorous rootstocks.  J. Hort. Sci. and Biotechnology 81:211-218.

#139.*  Gordon, C., A. Rosati, C. Damiano and T.M. DeJong. 2006. Seasonal effects of light exposure, temperature, trunk growth and plant carbohydrate status on the initiation and growth of epicormic shoots in Prunus persica. J. Hort. Sci. and Biotechnology 81:421-428.

#140.*  Solari, L.I. and T.M. DeJong. 2006.  The effect of root pressurization on water relations, shoot growth, and leaf gas exchanges of peach (Prunus persica) trees on rootstocks with differing growth potential and hydraulic conductance.  J. Experimental Botany 57: 1981-1989.

#141.*  Solari, L.I., S. Johnson, and T.M. DeJong.  2006.  Relationship of water status to vegetative growth and leaf gas exchange of peach (Prunus persica) trees on different rootstocks.  Tree Physiology 26:1333-1341.

#142.*  Solari, L.I., S. Johnson, and T.M. DeJong. 2006.  Hydraulic conductance characteristics of peach (Prunus persica) trees on different rootstocks are related to biomass production and distribution. Tree Physiology 26: 1343-1350.

• Dejong, Theodore M. and Yaffa. L. Grossman.  1994.  A supply and demand approach to modeling annual reproductive and vegetative growth of deciduous fruit trees.  HortScience 29(12):1435-1442.
  
  
• Grossman, Yaffa L. and Theodore M. Dejong.  1994.  Carbohydrate requirements for dark respiration by peach vegetative organs.  Tree Physiology 14:37-48.

• Grossman, Yaffa L. and Theodore M. Dejong.  1994.  PEACH: A simulation model of reproductive and vegetative growth in peach trees.  Tree Physiology 14:329-345.
  
  
• Dejong, Theodore M., Kevin R. Day, James F. Doyle, and R.S. Johnson.  1994.  The Kearney Agricultural Center Perpendicular "V" (KAC-V) orchard system for peaches and nectarine.  HortTechnology 4(4):362-367.
  

• Retzlaff, W.A., W. W. Barnett, L.E. Williams, and T.M. Dejong.  1994.  Ozone air pollution increases petroleum spray oil phytotoxicity.  HortScience 29(2):93-94.
  
  
• Pavel, E.W. and T. M. Dejong.  1995.  Seasonal patterns of nonstructural carbohydrates of apple (Malus pumila Mill.) fruits: Relationship with relative growth rates and contribution to solute potential. : Journal of Horticultural Science 70(1):127-134.
  

• Grossman, Y. L. and T. M. Dejong.  1995.  Maximum fruit growth potential and seasonal patterns of resource dynamics during peach growth.  Annals of Botany 75:553-560.
  
  
• Grossman, Y. L. and T. M. Dejong.  1995.  Maximum fruit growth potential following resource limitation during peach growth.  Annals of Botany 75:561-567.
  

• Grossman, Y. L. and Theodore M. Dejong.  1995.  Maximum vegetative growth potential and seasonal patterns of resource dynamics during peach growth.  Annals of Botany 76:473-482.
  

• Dejong, Theodore M. and Yaffa L. Grossman.  1995.  Quantifying sink and source limitations on dry matter partitioning to fruit growth in peach trees.  Physiologia Plantarum 95:437-443.
  

• Retzlaff, William, William W. Barnett, Larry E. Williams, and Theodore M. Dejong.  1996.  Ozone air pollution increases spray oil phytotoxicity.  California Agriculture 50(2):21-23.
  
  
• Berman, M. E. and T. M. Dejong.  1996.  Water stress and crop load effects on fruit fresh and dry weights in peach (Prunus persica): Tree Physiology 16:859-864.
  
  
• Berman, M. E. and T. M. Dejong.  1997.  Diurnal patterns of stem extension growth in peach (Prunus persica): Temperature and fluctuations in water status determine growth rate.  Physiologia Plantarum 100:361-370.
  

• Berman, M. E. and T. M. Dejong.  1997.  Crop load and water stress effects on daily stem growth in peach (Prunus persica).  Tree Physiology 17:467-472.
  
  
• Saenz, J. L., T. M. Dejong, and S. A. Weinbaum.  1997.  Nitrogen stimulated increases in peach yields are associated with extended fruit development period and increased fruit sink capacity.  Journal of the American Society for Horticultural Science 122(6):772-777.
  
  
• Crisosto, Carlos H., R. Scott Johnson, Ted Dejong, and Kevin R. Day.  1997.  Orchard factors affecting postharvest stone fruit quality.  HortScience 32(5):820-823.
  

• Retzlaff, W. A., L. E. Williams, and T.M. DeJong.  1997.  Growth and yield response of commercial bearing-age 'Casselman' plum trees to various ozone partial pressures.  Journal of Environmental Quality 26:858-865.
  
  
• DeJong, Theodore M. and Kay Ryugo.  1998.  Carbohydrate assimilation, translocation, and utilization.  Walnut Production Manual, University of California, Division of Agriculture and Natural Resources, Publication 3373, pp. 109-114.
  
  
• Berman, M. E., A. Rosati, L. Pace, Y. L. Grossman, and T. M. DeJong.  1998.  Using simulation modeling to estimate the relationship between date of fruit maturity and yield potential in peach.  Fruit Varieties Journal 52(4):229-235.
  

• Grossman, Y. L. and T. M. DeJong.  1998.  Training and pruning system effects on vegetative growth potential, light interception, and cropping efficiency in peach trees.  Journal of the American Society of Horticultural Science 123(6):1058-1064.
  
  
• Rosati, A., G. Esparza, T. M. DeJong, and R. W. Pearcy.  1999.  Influence of canopy light environment and nitrogen availability on leaf photosynthetic characteristics and photosynthetic nitrogen-use efficiency of field-grown nectarine trees.  Tree Physiology 19:173-180.
  

• DeJong, T. M., W. Tsuji, J. F. Doyle, and Y. L. Grossman.  1999.  Comparative economic efficiency of four peach product systems in California.  HortScience 34(1):73-78.
  
  
• DeJong, T. M.  1999.  Developmental and environmental control of dry-matter partitioning in peach.  HortScience 34(6):1037-1040.
  
  
• Rosati, A., K. R. Day, and T. M. DeJong.  2000.  Distribution of leaf mass per unit area and leaf nitrogen concentration determine partitioning of leaf nitrogen within tree canopies.  Tree Physiology 20:271-276.
  
  
• Weinbaum, Steven A., Theodore M. DeJong, and John Maki.  2001.  Reassessment of seed influence on return bloom and fruit growth in 'Bartlett' pear.  HortScience 36(2):295-297.
  

• Rosati, A., F. W. Badeck, and T. M. DeJong.  2001.  Estimating canopy light interception and absorption using leaf mass per unit leaf area in Solanum melongena.  Annals of Botany 88:101-109.
  

• Klein, I., G. Esparza, S. A. Weinbaum, and T. M. DeJong.  2001.  Effects of irrigation deprivation during the harvest period on leaf persistence and function in mature almond trees.  Tree Physiology 21:1063-1072.
  

• Esparza, G., T. M. DeJong, S. A. Weinbaum, and I. Klein.  2001.  Effects of irrigation deprivation during the harvest period on yield determinants in mature almond trees.  Tree Physiology 21:1073-1079.
  
  
• Esparza, G., T. M. DeJong, and S. A. Weinbaum.  2001.  Effects of irrigation deprivation during the harvest period on nonstructural carbohydrate and nitrogen contents of dormant, mature almond trees.  Tree Physiology 21:1081-1086.
  
  
• Rufat, Josep and Theodore M. DeJong.  2001.  Estimating seasonal nitrogen dynamics in peach trees in response to nitrogen availability.  Tree Physiology 21:1133-1140.