PT  - JOURNAL ARTICLE
AU  - Sobrado, M.A.
TI  - Leaf Photosynthesis of the Mangrove Avicennia Germinans as Affected by NaCl
DP  - 1999 Dec 1
TA  - Photosynthetica
PG  - 547--555
VI  - 36
IP  - 4
AID - 10.1023/A:1007092004582
IS  - 03003604
AB  - In leaves of the mangrove species Avicennia germinans (L.) L. grown in salinities from 0 to 40 ‰, fluorescence, gas exchange, and δ&lt;sup&gt;13&lt;/sup&gt;C analyses were done. Predawn values of F&lt;sub&gt;v&lt;/sub&gt;/F&lt;sub&gt;m&lt;/sub&gt; were about 0.75 in all the treatments suggesting that leaves did not suffer chronic photoinhibition. Conversely, midday F&lt;sub&gt;v&lt;/sub&gt;/F&lt;sub&gt;m&lt;/sub&gt; values decreased to about 0.55-0.60 which indicated strong down-regulation of photosynthesis in all treatments. Maximum photosynthetic rate (P &lt;sub&gt;max&lt;/sub&gt;) was 14.58 ± 0.22 µmol m&lt;sup&gt;-2&lt;/sup&gt; s&lt;sup&gt;-1&lt;/sup&gt; at 0 ‰ it decreased by 21 and 37 % in plants at salinities of 10 and 40 ‰, respectively. Stomatal conductance (g &lt;sub&gt;s&lt;/sub&gt;) was profoundly responsive in comparison to P &lt;sub&gt;max&lt;/sub&gt; which resulted in a high water use efficiency. This was further confirmed by δ&lt;sup&gt;13&lt;/sup&gt;C values, which increased with salinity. From day 3, after salt was removed from the soil solution, P &lt;sub&gt;max&lt;/sub&gt; and g &lt;sub&gt;s&lt;/sub&gt; increased up to 13 and 30 %, respectively. However, the values were still considerably lower than those measured in plants grown without salt addition.