John Jifon

John L. Jifon, Ph.D.
Assistant Professor Horticultural Sciences
Texas AgriLIFE Research


Overall Research Interest:
Dr. Jifon’s research is focused on environmental stress physiology of plants — the physiological, biochemical and molecular mechanisms and traits that confer tolerance to environmental stresses (especially to drought, radiation/temperature extremes, and nutrient imbalance). A key theme in his research is to use integrated measurements obtained at leaf, whole-plant, and stand levels to study factors that regulate photosynthetic efficiency, water/nutrient use efficiency, assimilate partitioning, yield and quality. The aim is to use the information gained in these studies to develop practical strategies to optimize productivity and quality by improving plant tolerance to environmental stresses.


Improving crop water use efficiency and water conservation:
A better understanding of plant water use is necessary in improve irrigation practices to increase crop water use efficiency. The objective of this project is to increase crop water use efficiency without sacrificing yield/quality using regulated deficit irrigation (RDI) based on crop developmental stage and evapotranspiration data. The approach is to monitor soil moisture depletion patterns and weather variables (solar radiation, temperature, wind, and humidity). Irrigation is then scheduled based on crop evapotranspiration (ETc) using modified FAO crop coefficients. The effects of irrigating at 25, 50, 75 or 100% ETc on leaf gas exchange, and water relations, yield, quality, water use efficiency and water savings are measured. Benefits from this research are improved on-farm water conservation; reduced production costs related to water supply; increased water availability for non-agriculture uses; improved knowledge of drought effects on plant physiology, development and yield.

Improving the health-promoting properties of foods:

Phytochemicals are compounds accumulated by plants which have health-promoting properties such as prevention of certain chronic ailments. Many of these compounds also protect plants from damaging effects of environmental stresses. A better understanding of the environmental conditions and processes controlling the synthesis and accumulation of phytochemicals will facilitate development of strategies to improve not only plant tolerance to stresses, but also the health-promoting properties of target crops.
The benefit to consumers of this research is improved eating quality and health-promoting properties of vegetables; reduced health care costs. Benefits to growers, retailers and industry include improved market quality, shelf life and value of produce.
Bioenergy feedstock production: Agronomic considerations:
The success crops grown primarily for energy depends on the efficiency, profitability and sustainability of the crop production system. Research in this area is evaluating a range of potential bioenergy feedstock crops for adaptability to Texas growing conditions in order to optimize environmental and agronomic (water/nutrient use, yield, energy density) practices for their sustainable production. This research benefits local and national economies, creates alternative land use, crops and markets. Consumers benefit by having a reduced reliance on fossil fuels. The environment also benefits by having increased carbon sequestration in soils and reducing greenhouse gas emissions into the atmosphere.