Plant Ecophysiology under Agrivoltaic Light

Project status: Proposed research framework for experimental collaboration.

Agrivoltaic systems are commonly characterised by the amount of solar radiation transmitted to crops. However, photovoltaic configuration also determines when and how radiation reaches the crop canopy. Different systems can create contrasting sequences of high irradiance, partial shade, and shade–sun transitions, even when crops receive similar cumulative daily radiation.

For plants, these light patterns may not be physiologically equivalent. Photosynthesis does not respond instantaneously after a period of shade, and stomatal conductance can adjust on a different timescale. Repeated light transitions may therefore generate cumulative carbon losses and changes in water use that are not represented by mean irradiance or daily light integral alone.

Are agrivoltaic light environments that provide comparable cumulative radiation biologically equivalent, or do differences in the frequency, duration, and timing of shade–sun transitions generate different crop carbon and water outcomes?

H1 — Temporal organisation of light. At comparable cumulative photon exposure, different temporal light patterns may produce different cumulative carbon gains because repeated shade–sun transitions impose photosynthetic induction costs.

H2 — Shade history and physiological response. The response following a return to high irradiance may depend on the duration and intensity of the preceding low-light period. Longer shade periods may increase the time required for photosynthesis to recover.

H3 — Carbon–water coordination. The physiological effect of a light transition may depend on the coordination between photosynthesis and stomatal conductance. Leaf temperature, atmospheric vapour-pressure deficit, and plant water status may further modify these responses.

The project would first characterise agrivoltaic light environments using high-frequency PPFD measurements. Measurements would describe shade duration, high-light periods, transition frequency and magnitude, timing during the day, and cumulative photon exposure.

Representative light patterns could then be reproduced or approximated during dynamic gas-exchange measurements. Experimental comparisons would separate total light quantity from its temporal organisation—for example, comparing a few relatively long shade events with several shorter shade–sun transitions while maintaining approximately comparable cumulative photon exposure.

Core physiological measurements could include net CO₂ assimilation, stomatal conductance, transpiration, photosynthetic induction and recovery, leaf or canopy temperature, and cumulative carbon gain and water loss. Chlorophyll fluorescence could be included selectively when needed to distinguish photochemical from stomatal or biochemical limitations.

Field measurements during naturally occurring light transitions could connect short-term physiological responses with canopy development, phenology, biomass accumulation, yield components, and final crop performance.

The objective is not another broad agrivoltaic-versus-open-field comparison, but to determine whether temporal light characteristics and physiological response kinetics provide explanatory information beyond cumulative radiation alone.

The research connects:

PV configuration → temporal light pattern → photosynthetic and stomatal response → carbon and water consequences → crop performance

The initial aim is not to develop a photovoltaic tracking algorithm. Instead, the project would generate plant-response information that could later support crop-aware photovoltaic design and management strategies.

This research framework would add an experimental plant-ecophysiology perspective to interdisciplinary agrivoltaic research by connecting photovoltaic-generated light environments with measured plant function.

My research background in plant ecophysiology, canopy architecture, light interception, heterogeneous light environments, plant water relations, and sustainable cropping systems provides the biological foundation for this work.

This proposed research builds on my previous experimental work on canopy architecture, light interception, crop responses to heterogeneous light environments, and plant–environment interactions. Selected publications providing the scientific foundation for this direction include:

Cici, S.Z.H., Adkins, S.W., Hanan, J. (2008). A canopy architectural model to study the competitive ability of chickpea with sowthistle. Annals of Botany, 101, 1311–1318. https://doi.org/10.1093/aob/mcn040

Cici, S.Z.H., Adkins, S.W., Hanan, J. (2009). An a priori cellular automaton model of crop–weed competition for light. Computers and Electronics in Agriculture, 70, 295–302. https://doi.org/10.1016/j.compag.2009.06.014

Cici, S.Z.H. (2014). The influence of environmental light on the phenological development of annual sowthistle. Agrotechnology, 3, 134. https://doi.org/10.4172/2168-9881.1000134