Effect of Light - Water Interaction on the Growth and Photosynthesis of Vanilla planifolia Andrews
Flavio Moreno, María C. Díez G. and Edison A. Gantiva R.
Vanilla (Vanilla planifolia Andrews) is a CAM plant of great economic importance in the market of flavorings. Wild plants initially grow in the shaded understory and then ascend to the canopy where they bloom. Therefore, it is expected that this species is able to acclimatize to different light and humidity conditions. We evaluated if the lighting conditions in which the plant grows can help to moderate the effects of drought. For this, we performed an experiment in a tropical lowland of Colombia, where vanilla plants growing in relative light (RL) of 8%, 17%, 31% and 67% were submitted to dehydration and rehydration processes. Then, the effect on CO2 assimilation, titratable acidity, quantum efficiency of the Photosystem II (Fv / Fm) and the growth of the liana were measured. Under intermediate RL conditions (17% and 31%), parameters such as CO2 assimilation, nocturnal accumulation of organic acids, and growth presented the best response to water deficit, as well as the best recovery after rehydration. The combined effects of water stress and high luminosity caused irreversible damage in photosynthesis and growth in the RL treatment of 67%.
Keywords: CAM photosynthesis, light aclimatation, water shortage, Orchidaceae