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Tropical Plant Ecophysiology Lab

Tropical Plant Ecophysiology Lab



    The Plant Ecophysiology group studies plant responses to abiotic factors (e.g., flooding, drought, wind, irradiance and atmospheric CO2) and biotic factors (insects and diseases) with emphasis on subtropical and tropical horticultural crops. Plant responses studied include leaf gas exchange variables, plant water use, xylem sap flow, plant growth and yield. Plant responses to biotic factors are investigated in cooperation with entomologists and plant pathologists.

    The limestone soil, high water table, and subtropical climate in south Florida provide an ideal environment for development of numerous plant stresses. We focus on understanding physiological bases for plant responses to these stresses in order to develop methods of avoiding or mitigating the negative impacts of these stresses on plants.

    Another focus of the program is the development of best management practices to increase the compatibility of agriculture with the adjacent natural and urban ecosystems.


Our research focuses on plant ecophysiology with the primary aim of assessing the effects of environmental stresses on whole-plant physiology of subtropical and tropical horticultural crops. We also collaborate with colleagues in other disciplines to determine the interactions of biotic and abiotic stresses on crop physiology.

Leaf gas exchange, chlorophyll fluorescence, and plant water relations are determined as physiological indicators of plant stress and to identify mechanism underlying the causes of these stresses.


    Current Doctoral Student's Research Project

    Environmental physiology and biochemical responses of avocado ecotypes to flooding stress (Melinda Yin, Ph.D. Candidate)

    This project focuses on understanding and quantifying differences among Mexican (M), Guatemalan (G) and West Indian (WI) ecotypes of avocado (Persea americana Mill.) to short-term flooding and how they differ in recovery. Flooding tolerance is being examined through the lens of plant physiology (i.e., leaf gas exchange, chlorophyll fluorescence) and biochemistry (i.e., carbohydrates, reactive oxygen species, antioxidants). We aim to identify if certain carbohydrates and their mobility and accessibility under flooded conditions enhance potential to survive short-term flooding. Lastly, chemical priming of avocado seedlings will be tested in the context of improving seedling survival during a later flooding stress.


    Current M.S. Student's Research project

    Physiological and Developmental Responses of Vanilla planifolia to Photoselective Shade Nets (Federico Sanchez, M.S. Student)

    This study is assessing the effects of different color photoselective shade netting (CPSN) on vanilla (Vanilla planifolia) plant physiology (leaf gas exchange, leaf chlorophyll index, chlorophyll fluorescence), morphology (leaf size, number of leaves and flowers), and development (time of first flowering, fruiting). CPSNs not only reduce light intensity, but also alter the spectral quality of light. By growing vanilla plants in cages with different colored CPSNs under the same light intensity, we are altering the light quality without changing the light intesity. The impacts of different color CPSNs on the spectral quality of plant absobed and reflected light, as well as plant physiology, morphology and development are being assessed. Potential effects such as increased photosynthetic efficiency, faster growth, greater biomass, accelerated flowering, increased flower and fruit numbers and size may be associated with specific CPSN treatments. Results from this project may provide novel ways to improve the cultivation of vanilla. 


    Current Collaborative Research Projects

    Plant Safety, Horticultural Benefits, and Disease Efficacy of Essential Oils for Use in Organically Grown Fruit Crops: From the Farm to the Consumer

    This USDA, OREI funded research and extension project led by Dr. Ali Sarkhosh (University of Florida, Gainesville) is a collaboration among the Univeristy of Florida, the University of Georgia, Clemson University, the University of California-Riverside, the University of Hawaii and the U.S. Department of Agriculture. The project will determine the efficacy of organically certified plant essential oils on controlling fungal diseases in avocado, mango, peach and blueberry crops and the best application rates and timing for the most efficient disease control. Essential oil effects on controlling insect pests are also being assessed.

    Our lab in collaboration with Dr. Romina Gazis' and Dr. Jonathan Crane's labs is determining the effects of plant derived essential oils on controlling anthracnose disease, caused by the fungus Colletototrichum gloeosporioides, in avocado and mango leaves and fruit. Experiments are being conducted in the lab (in vitro studies), greenhouse (using potted plants) and in organic orchards owned and managed by south Florida growers.

    Reducing Avocado Losses To Major Challenges By Improving Resistance Selection And Disease Management Using Next Generation Technologies

    This USDA, SCRI funded project led by Dr. Patty Manosalva (University of California, Riverside) is a collaboration among the University of California-Riverside, the University of Florida, the University of Hawaii, Texas A&M University, the Univeristy of Milan (Italy), and the U.S. Department of Agriculture.

    A major constraint to growing avocado trees in many parts of the world, including California, is Phytophthora root rot (PRR) caused by the fungus Phytophthora cinnamomi. Laurel wilt (LW), a vascular disease caused by the fungus Raffealea lauricola, has killed thousands of avocado trees in Florida orchards. LW is not in California but is spreading westward from the east coast of the U.S. and is anticipated to eventually reach California.

    The overall goal of this  project is to control PRR and LW with PRR- and salinity-tolerant avocado rootstocks developed by researchers at the University of California, Riverside.  These rootstocks will be tested  in multistate field trials.  Other aspects of the project involve testing physiological responses to LW of these rootstocks with different scions, evaluating new fungicides for PRR control, developing in-field DNA- and protein-based diagnostic tools for PRR and LW, and developing remote sensing technology for diagnostics and disease management.

    Our lab in cooperation with Dr. Romina Gazis’ lab is testing the susceptibility and physiological responses (leaf gas exchange, plant water use, xylem sap flow) to LW of these new PRR- and salinity-tolerant avocado rootstocks grafted with different scions. Also, in cooperation with Dr. Jonathan Crane’s program, we are field testing the performance of these rootstocks with different scions under south Florida avocado growing conditions.

    Integrating Data From Ground Measurements, Unmanned Aerial Vehicles, And Modeling To Quantify Plot Scale Evapotranspiration

    This project funded by the USDA-NIFA and led by Dr. Haimanote Bayabil (University of Florida, TREC, Homestead) focuses on increasing irrigation efficiency of bean and corn crops by developing methodology for artificially intelligent (AI) irrigation systems that estimate evapotranspiration.  Data are being integrating from multiple sources from both ground and aerial measurements for use in developing hydrologic and crop models. The goal  is to develop a method for measuring plot-level evapotranspiration rates  that will allow the implementation of precision irrigation management practices at fine resolutions and fine-tuning of crop growth and hydrologic models. Implementing precision water management practices should result in water savings but also in more efficient nutrient use and increased crop production. Crop water use and plant stress are being quantified at the individual plant and field levels.  Our lab is assisting in quantifying  stress and plant water use at the plant level.




Many of our lab members are international, particularly from countries where subtropical and tropical horticultural crops are grown. Graduate students take classes on the main campus in Gainesville and conduct their research at the Tropical Research and Education Center (TREC). Most of them finish their coursework in 2-3 semesters and then move to TREC to concentrate on their research and stay in graduate student housing.


    Current Lab Members

    Bruce Schaffer - Proffesor

    • Postdoc  Biology, University of Heidelberg, Germany, 1985
    • Ph.D. Horticulture (Plant Physiology), Virginia Tech University, 1985
    • M.S. Forest Biology, Colorado State University, 1981 
    • B.S. Entomology (Zoology, 2nd Major), Colorado State University, 1978


    Ana I. Vargas - Biologist Scientist III and Lab Manager

    • M.S. Engineering Management, Florida International University, 2012
    • B.S. Biology, Florida International University, 2011
    • B.S. Agronomy, University of Pinar del Rio, Cuba, 1998


    Melinda Yin - Ph.D. Student

    • M.S. Horticulture, University of Arkansas, 2017
    • B.S. Plant Sciences, University of California, 2015




    Federico Sanchez - M.S.Student

    • M.B.A., Harvard Business School, 1995
    • Bachelor in Business Administration, UCAB, Caracas, 1992



    Dainiel Avila - Volunteer

    • Project Manager, B&I Contractors