Our Team

GIULIA MARINO

Ass. Professor of Cooperative Extension in Orchard Systems

Giulia is an Assistant Professor of Cooperative Extension at the Department of Plant Sciences, UC Davis. Her research and extension focus on using physiological information to develop management practices that would improve efficiency of resource use and profitability of orchard systems.

Dr. Marino completed her PhD at the University of Palermo, Italy, where she studied the physiology of alternate bearing in Pistacia vera L.. Her first post doc experience, in Italy, focused on proximate sensing and plant-based cultivar-specific water management in olive. She also worked on autochthonous germplasm conservation and agronomic characterization. In 2016 she started a post doc at the University of California (Davis) aiming to understand pistachio water use dynamics under saline-sodic stresses.

PAULA GUZMÁN-DELGADO

Ass. Professional Researcher

Paula is a Professional Researcher in the Department of Plant Sciences at UC Davis. Her research focuses on how plants respond to environmental conditions and management practices, with particular emphasis on water and carbon dynamics.

Dr. Guzmán-Delgado earned her PhD in 2014 from the Universidad Politécnica de Madrid, Spain, where she studied the physico-chemical properties of plant surfaces, with a focus on the cuticle. She joined UC Davis in 2016. She has worked across a wide range of species, systems, and scales, developing an integrative approach to understanding plant physiological functions. Her work aims to uncover mechanisms that can be translated into practical strategies for a more resilient agriculture under global change.

AMRIT POKHREL

Ph.D. Student Researcher (University of California, Davis)

Amrit is a Ph.D. student at Horticulture and Agronomy Graduate Group, University of California Davis, and is co-advised by Dr. Giulia Marino, and Dr. Paula Guzman Delgado, and Dr. Troy Magney. He joined Tree System Lab in 2023 as an Assistant specialist and helped to manage Davis lab and projects for a year before starting his PhD. He is interested in integrating plant physiology and remote sensing. His project is currently focused on identifying physiological water stress indicators in orchard crops using proximal and remote sensing approaches. He received his BS in Agriculture from IAAS, Lamjung Campus, Nepal (2019) and MS in Crop and Soil Sciences (2023) from University of Georgia Tifton Campus.

AILEEN SALAS

Graduate Student Researcher (University of California, Davis)

Aileen Salas is an M.S. student at UC Davis's Horticulture and Agronomy Graduate Group. She began her work with the Tree System Lab in May 2022 as a Student Intern, helping with various on-farm studies related to water stress and fruit development. She became skilled in performing and interpreting several physiological field measurements, such as stem water potential and leaf gas exchange. Starting in September 2024, she is now co-advised by Dr. Paula Guzman Delgado and Dr. Giulia Marino, where she will continue to integrate plant physiology parameters for farm management through multi-site research projects across California, working with pistachios, almonds, cherries, and agave. She is also investigating fruit development and ripening processes in almonds. She graduated from Fresno State in December 2023 with a B.S. in Agricultural Plant Sciences and plans to graduate with her M.S. at UC Davis in June 2026. She is interested in doing on-farm/extension applied research and using a physiological approach to optimize orchard system management strategies.

DONALD WILLIAMS III

Graduate Student Researcher (Kearney Agricultural Research and Extension Center)

Don is a California native, born and raised in the San Joaquin Valley (SJV). He joined the Kearney Agricultural Research and Extension (KARE) center in June 2022 and is currently a graduate student researcher from California State University, Fresno. He plans to complete his M.S. in Agricultural Plant Sciences in December 2025, with an emphasis in plant physiology and soil science.

His thesis research focuses on pistachios grown under drought and saline conditions on the west side of the SJV, with particular attention to the effects of excess boron levels and boron toxicity on crop yield.

At Kearney, Don oversees an olive cultivar trial evaluating N applications and cultivar performance under SJV conditions. He is also actively involved in multi-site research projects across the SJV, working with pistachios, almonds, and agave.

In 2022, Don earned his B.S. in Agricultural Plant Sciences from CSU Fresno, graduating Magna Cum Laude. He holds an A.S. in Agricultural Plant Sciences from College of the Sequoias, where he graduated with honors in 2020, received a Plant Science Skill Certificate in 2019, and was named "Outstanding Student in Plant Science" for 2017–2018.

BREANNA POOL

Undergraduate Student Lab Assistant (University of California, Davis)

Breanna is an Environmental Horticulture and Urban Forestry major who will be graduating with her Bachelor’s at UC Davis in Spring 2025. She will be joining the Horticulture and Agronomy Graduate Group in Fall 2025 to complete her Master’s. Co-advised by Dr. Giulia Marino and Dr. Paula Guzman Delgado, Breanna hopes to expand her experience within tree and plant physiology. She is most interested in applied research and enjoys being out in fields doing various measurements.

Previous Lab Members

Emily Santos

Daniel Ruiz