Abstract
Water availability is the main factor that explains current patterns of palm abundance. However, the interaction between water stress and increasing atmospheric CO2 concentrations caused by climatic change and its effects on palm physiology remain poorly known. Macauba palm is a widespread Neotropical species commonly found in ecosystems subjected to seasonal drought and has potential use in oil production. The present work investigated the influence of increased CO2 concentrations on photosynthetic responses to drought in macauba palm plants. Exposure to increased CO2 concentrations led to up-regulation of photosynthesis through higher stomatal conductance and improved light and water use efficiency. Macauba palm plants under water stress, irrespective of CO2 concentration, were able to maintain constant levels of proline and chlorophyll, while preventing oxidative damage. Plants grown at higher CO2 concentrations were more capable of recovering from drought due to higher Rubisco carboxylation rate (Vc max) and electron transport rate (J max), which prevented a reduction in total dry mass at the end of the stress period. Stomatal control of photosynthesis, coupled with the prevention of severe damage under stress, would allow efficient biomass production by the macauba palm under future scenarios of climate change.
Highlights
The effects of climate change on photosynthesis in C3 plants are mainly related to the positive effect of increased atmospheric CO2 concentration ([CO2]) on the carboxylation capacity of Rubisco and to decreased transpiration rate (Long et al 2004)
This photosynthetic acclimation in plants exposed to long-term high [CO2] is commonly defined as down-regulation of photosynthesis, a process triggered by cumulative reduction in the content of Rubisco in leaves and the concomitant reduction in the photosynthetic electron transport rate (ETR), along with source–sink imbalance (Ainsworth et al 2004; Long et al 2004; Gamage et al 2018)
The net photosynthetic rate approximated zero, regardless of the CO2 concentration, after 25 days of exposure to drought during the first cycle of water stress (Fig. 1A and B).Recovery after rehydration in the first stress cycle was reached after two days for plants grown at [CO2]700, but was delayed by five days for plants grown at [CO2]400
Summary
The effects of climate change on photosynthesis in C3 plants are mainly related to the positive effect of increased atmospheric CO2 concentration ([CO2]) on the carboxylation capacity of Rubisco and to decreased transpiration rate (Long et al 2004). Some initial stimulus of photosynthesis can be observed immediately upon exposure to high [CO2], photosynthetic capacity is often reduced after a long-term growth at elevated CO2 levels (Leakey et al 2009; Córdoba et al 2017). This photosynthetic acclimation in plants exposed to long-term high [CO2] is commonly defined as down-regulation of photosynthesis, a process triggered by cumulative reduction in the content of Rubisco in leaves and the concomitant reduction in the photosynthetic electron transport rate (ETR), along with source–sink imbalance (Ainsworth et al 2004; Long et al 2004; Gamage et al 2018).
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
