Remote Detection of Growth Dynamics in Red Lettuce Using a Novel Chlorophyll a Fluorometer

Matthew Urschel,Tessa Pocock

doi:10.3390/agronomy8100227

Matthew Urschel, Tessa Pocock

Open Access

https://doi.org/10.3390/agronomy8100227

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Abstract

The production of food crops in controlled environment agriculture (CEA) can help mitigate food insecurity that may result from increasingly frequent and severe weather events in agricultural areas. Lighting is an absolute requirement for crop growth in CEA, and is undergoing rapid advances with the advent of tunable, light emitting diode (LED) systems. The integration of these systems into existing CEA environmental control architectures is in its infancy and would benefit from a non-invasive, rapid, real-time, remote sensor that could track crop growth under different lighting regimes. A newly-developed remote chlorophyll a fluorescence (ChlF) sensing device is described herein that provides direct, remote, real-time physiological data collection for integration into tunable LED lighting control systems, thereby enabling better control of crop growth and energy efficiency. Data collected by this device can be used to accurately model growth of red lettuce plants. In addition to monitoring growth, this system can predict relative growth rates (RGR), net assimilation rates (NAR), plant area (PA), and leaf area ratio (LAR).

Highlights

Evidence for anthropogenic climate change along with predicted demographic trends toward increased habitation in cities are imposing new challenges on global agriculture and are threatening food security for a global population that is projected to reach 11.2 billion people by the end of the21st century [1,2]
Most light control systems are based on instantaneous light values, past weather, or predictive weather patterns, but systems based on the accumulation of photosynthetically-active radiation (PAR) during the day (DLI) have resulted in further optimization of crop yield and energy use [5,6]
We have demonstrated that far red chlorophyll a fluorescence (ChlF) emission at 740 nm (ChlF740nm ) measured in the light-adapted state is strongly correlated with observed changes in fresh weight (FW), dry weight (DW) and plant area (PA) of experimental plants (Table 1)

Summary

Introduction

Evidence for anthropogenic climate change along with predicted demographic trends toward increased habitation in cities are imposing new challenges on global agriculture and are threatening food security for a global population that is projected to reach 11.2 billion people by the end of the21st century [1,2]. CEA protects crops from inclement weather while allowing for consistent and predictable crop production through rigorous environmental control. The daily light integral is the accumulated light reaching the canopy, and is measured as moles of photons m–2 day–1 within the photosynthetically-active radiation (PAR) region of 400–700 nm. It is specific for different crops and is positively correlated with growth and crop yield. Most light control systems are based on instantaneous light values, past weather, or predictive weather patterns, but systems based on the accumulation of PAR during the day (DLI) have resulted in further optimization of crop yield and energy use [5,6].

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