Cotyledon Competency in CEA: Light Response Curve Analysis across Emerging Mizuna Leaf Tissues


Controlled environment agriculture allows growers to deliver precise lighting conditions to accelerate plant growth, development, and quality metrics. While providing optimum light conditions is desirable, electricity costs associated with lighting account for 40-50% of overall farm operational costs (Bhuiyan R and van Iersel MW, 2021). Interest in reducing costs associated with sole source LED lighting from academic institutions and indoor farms has led to the exploration of dynamic lighting - altering light intensity, duration, and spectrum to provide crops with only as much light energy as can be utilized for photosynthetic activity. Quantifying plant photosynthetic competency is commonly done by measuring rates of leaf carbon dioxide assimilation as a function of PPFD via a light response curve. This study investigates differences in light response curve parameters between cotyledon, primary, and secondary leaves in Mizuna to assess the potential for dynamic lighting regimes based on plant developmental stage. Despite comparable maximum photosynthetic capacities among the three leaf types, only cotyledons and secondary leaves shared similar responses in terms of light compensation points, quantum yields, and dark respiration rates. However, primary and secondary leaves had greater congruence in terms of Qsat, defined here as the PPFD intensity at which the slope of the light response curve reaches 80% of the quantum yield slope value. These findings suggest that Mizuna leaves have altered photosynthetic competency in terms of light response curve parameters depending on developmental stage.

In American Society for Horticultural Science 2021
Christopher Nieters
Christopher Nieters
Research Associate

Phys | Fluxes | Photons | Fluorescence