Location: Application Technology Research
Project Number: 5082-21000-001-32-S
Project Type: Non-Assistance Cooperative Agreement
Start Date: Sep 1, 2020
End Date: Aug 31, 2022
The three main objectives of this research will be to: 1) identify morphological and physiological acclimation responses based on the timing, duration, and concentration of CO2 throughout production for horticultural crops; 2) develop protocols for CO2 injection in controlled environments based on crop-specific acclimation responses and evaluate the resulting impacts to crop yield and quality (e.g., flowering, nutrition); and 3) Improve control systems for managing CO2 in controlled environments based on the recommendations and management strategies developed.
For Objective 1, multiple experiments will be conducted in two growth chambers located at the cooperator's location to determine species-specific acclimation responses to elevated CO2 concentrations. Initial experiments will compare growth and photosynthetic responses under ambient (~410 µmol·mol–1) and elevated CO2 at varying concentrations. Growth and morphological acclimation to CO2 will be assessed through measurements such as biomass accumulation, stomatal density, and leaf mass area (g·cm–2). Physiological acclimation to CO2 over time will be determined through gas exchange measurements using a portable photosynthesis meter to determine the extent and timing of acclimation responses. A range of horticultural species including leafy greens, herbs, and floriculture crops will be evaluated. Based on results from Objective 1, the feasibility of adjusting CO2 concentrations throughout production to avoid acclimation responses in both greenhouse and growth chamber environments will be evaluated. Treatments will incorporate CO2 injection concentration and duration at varying intervals throughout production. In addition to evaluating crop-specific acclimation responses to elevated CO2, crop yield and quality will be assessed to determine further impacts to production. Specifically, where applicable, plant nutrition, carbohydrate partitioning, flowering, and other assessments of quality will be collected and analyzed. Protocols pertaining to CO2 injection will be developed as a resource for growers, including species-specific recommendations regarding the timing, duration, and concentration for CO2 injection to elicit desired growth or quality responses. These protocols will be outlined through multiple publications including peer-reviewed and trade journal articles. In Objective 3, based on the protocols developed from Objective 2, improvements to existing control systems will be developed for a variety of production environments. The incorporation and assessment of updated control systems will be conducted in collaboration with ARS.