CLIMATE CONTROL FOR BOOSTING CO₂ UPTAKE IN CAM ACTIVE SHORT DAY PLANTS BY SHIFTING TO LONG DAY CONDITIONS AFTER FLOWER INITIATION

CAM active short day plants as e.g., Kalanchoë, induce flowers after a specific short day period, usually controlled with light and black-out screens.
Day length is commonly controlled with a long day treatment as start up cultivation, followed by a prolonged short day period for flower induction.
Kalanchoë changes from young plants with C₃ to older plants with CAM metabolism.
As the diurnal dynamics of CAM can be divided in four stages with I Malic acid accumulation, II Morning transition, III Malate decarboxylation, and IV Evening transition; phases I-III can be shortened, which results in faster growth and using and increased phase IV. In this case climate control with optimized light, CO₂ and temperature control can be used to maximize crop growth.
For creating a climate control concept, experiments were performed.
Data show that especially CO₂ uptake during the light period is affected by day length, both in C3 (4 weeks) and CAM (11 weeks) active plants, whereas CO₂ uptake of CAM active plants and respiration in C₃ active plants are only affected to minor extend during the dark period.
Total CO₂ uptake is increased by approx. 25% when increasing the day length by 5 hours, i.e., decreasing phase I-III and increasing phase IV. Based on that a new climate control regime for Kalanchoë was developed, also taking fluctuations electricity spot-prices into account.

International Symposium on New Technologies for Environment Control, Energy-Saving and Crop Production in Greenhouse and Plant Factory – Greensys 2013

O. Körner, K.L. Nielsen

CAM, CO₂-uptake, DSS, model, simulation, software

https://doi.org/10.17660/ActaHortic.2014.1037.74