Lighting for Bush Bean (Phaseolus vulgaris) Production in a Controlled Environment

Date

Authors

Stoochnoff, Jared

Journal Title

Journal ISSN

Volume Title

Publisher

University of Guelph

Abstract

Plants use light as energy for photosynthesis and a signal to regulate growth and development. Each characteristic of the light environment, including the intensity, spectrum, photoperiod, and distribution, can influence net carbon exchange rates (NCER), morphology, and yield. Variable spectra light-emitting diode (LED) arrays allow for programmable control of the light environment and can be placed directly within the canopy to improve light distribution. The effects of light spectrum, intensity, and canopy distribution on green bush bean (Phaseolus vulgaris) were investigated within controlled environment systems (CES). Plant-light interactions were studied to develop an energy-efficient LED lighting strategy for high-density indoor production. Intracanopy lighting trials determined that improved light distribution increased bean yield, reduced height, and improved compatibility with high-density indoor production strategies. A spectral acclimation trial determined that increasing the proportion of blue light (400-500 nm) from 10 to 40% reduced height and promoted compact morphology during vegetative growth. Light response curves determined that acclimation to higher concentrations of blue light had a consistent but not statistically significant (α = 0.05) improvement on NCER performance. Sixty unique light spectra (%B:%G:%R) were applied at a fixed light intensity (250 μmol·m-2·s-1) to model the relationship between light spectrum, energy consumption, and canopy NCER. The maximum NCER (3.31 μmol CO2·m-2·s-1) and NCER/kW (23.34 μmol CO2·m-2·s-1·kW) were observed when applying 16B:24G:61R and 4B:7G:89R, respectively. Finally, fifteen spectra were applied at three light intensities (200, 300, and 400 μmol·m-2·s-1) to characterise plant-light interactions. The NCER, kW, and NCER/kW responses were used to create a “light response prism” comprised of stacked ternary plots. The maximum NCER (1.5 μmol CO2·m-2·s-1) was observed when applying ~100% red (600-700 nm) light at 400 μmol·m-2·s-1, and optimal NCER/kW balance (11.75 μmol CO2·m-2·s-1·kW) was observed when applying ~100% red light at 316 μmol·m-2·s-1. While this thesis provided a foundation to optimize bush bean lighting strategies, additional research is required to determine how long-term exposure to the light environments selected will impact crop morphology, yield, and nutritional quality.

Description

Keywords

Light Quality, LED Lighting, Intracanopy Lighting, Net Carbon Exchange Rate, Controlled Environment Agriculture, Dynamic LED Lighting

Citation

Stoochnoff, J., Johnston, M., Hoogenboom, J., Graham, T., & Dixon, M. (2022). Intracanopy lighting strategies to improve green bush bean (Phaseolus vulgaris) compatibility with vertical farming. Frontiers in Agronomy, 4. https://doi.org/10.3389/fagro.2022.905286