1. Leaf photosynthesis of the mangrove Avicennia germinans as affected by NaCl
- Creator:
- Sobrado, M. A.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- δ13C, carbon discrimination, down-regulation, fluuorescence, intercellular CO2 concentration, photoinhibition, salinity, stomatal conductance, succulence, and water use efficiency
- Language:
- Multiple languages
- Description:
- In leaves of the mangrove species Avicennia germinans (L.) L. grown in salinities from 0 to 40 ‰, fluorescence, gas exchange, and δ13C analyses were done. Predawn values of Fv/Fm were about 0.75 in all the treatments suggesting that leaves did not suffer chronic photoinhibition. Conversely, midday Fv/Fm values decreased to about 0.55-0.60 which indicated strong down-regulation of photosynthesis in all treatments. Maximum photosynthetic rate (Pmax) was 14.58 ± 0.22 µmol m-2 s-1 at 0 ‰ it decreased by 21 and 37 % in plants at salinities of 10 and 40 ‰, respectively. Stomatal conductance (gs) was profoundly responsive in comparison to Pmax which resulted in a high water use efficiency. This was further confirmed by δ13C values, which increased with salinity. From day 3, after salt was removed from the soil solution, Pmax and gs increased up to 13 and 30 %, respectively. However, the values were still considerably lower than those measured in plants grown without salt addition.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public