Abstract:

This paper is part of a study of the mangrove forests in the estuary area of the Jiulongjiang River of Fujian Province. It deals mainly with the reaction of certain enzymes in the leaves of two species of mangroves, Aegiceras corniculatum (Myrsinaceae) and Kandelia candel (Rhizophoraceae) to the changes in the soil salinity of tidal areas within the range of 3--12‰.The main results of tests and measurements are as follows:

1. The reactions of the contents of peroxidase isozyme and cytochrome oxidase isozyme in the leaves of the Aegiceras corniculatum to the change in the salinity of the soil indicate that increase in the soil salinity within the range of 3--12‰ will deepen and widen the spectral band of peroxidase isozyme and cytochrome oxidase isozyme, and may even cause new enzyme band to appear in the spectra.

2. As the soil salinity of tidal areas increases, the activity of the peroxidase in the leaves of the Aegiceras corniculatum will be intensified, but that of the glycollic acid oxidase in the leaves of the Kandelia candel will be weakened.

3. The interrelationship of the chlorophyll contents in the leaves of the two species of mangrove plants and the soil salinity shows that when the soil salinity is within the range of 3--8‰, there will be not much change in the chlorophyll content, but there is a peak when salinity is between 8--10‰, over which the chlorophyll content will drop. This shows that it is possible that there exists a critical point in the mangrove’s adaptability to the soil salinity of tidal areas.