Background:

The presence of crude oil (CO) in the soil can lead to the death of plant species that cannot acclimate to these conditions.

Questions:

What will be the physiological response of two tree species growing in soil contaminated with different concentrations of CO? What will be its physiological plasticity in this context?

Study species:

Haematoxylum campechianum L. and Tabebuia rosea (Bertol.) DC.

Study site:

Tabasco, Mexico; 2017.

Methods:

The physiological performance of two tree species growing in contaminated soils subjected to different concentrations of CO (15,170 to 15,600 mg kg-1) for 292 days was evaluated; we measured CO2 assimilation (A), transpiration (E), water use efficiency (EUA), quantic efficiency of photosystem II (Fv/Fm and ΦPSII), electron transport rate (TTE), non-photochemical quenching (DNE), water and osmotic potential, and chlorophyll content.

Results:

Low physiological plasticity was found in both species; there was a hormesis effect where individuals in the lower concentration of CO presented a physiological performance superior compared with plants in the control treatment. In T. rosea, there was an increase in the assimilation and transpiration rate, ΦPSII, DNE and Fv/Fm towards the end of the experiment; the TTE decreased from the beginning to the end of the experiment in all treatments. H. campechianum showed an increase in chlorophyll concentration towards the end of the experiment.

Conclusions:

Tabebuia rosea showed greater variability in their physiological response compared to H. campechianum, which suggests that they could be more sensitive to the presence of crude oil in the soil.

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