鹽分對五梨跤(Rhizophora stylosa)苗木生理反應之影響

Abstract

This study examined the effects of salinity on physiological responses including water status, chlorophyll concentration, triphenyl tetrazolium chloride (TTC) reduction, Cl(superscript -) and proline concentrations of the mangrove Rhizophora stylosa seedlings. The viviparous seedlings were grown in various concentrations of salinity containing 0.75, 1.5, 3.0% NaCl and control (0%) for 60, 120, and 150 days. The results indicated that leaf and stem water content of seedlings were high for those cultivated in 0.75, 1.5 and 3.0% NaCl, and were lowest for those in 0% NaCl. However, root water content of seedlings was not significantly affected by salinity. The salinity level showed less effect on relative water content (RWC) of the fully expanded leaves, which was maintained at 68.0-79.3%. Chlorophylls a, b concentrations and the total amount of chlorophylls were highest for seedlings cultivated in 0.75% NaCl, and were the lowest for the 0% NaCl treatment, the total amount of chlorophylls was only 1.21 mg g^(-1). TTC reduction of leaf tissue was not significantly affected by salinity, though seedlings grown at 0.75% NaCl had the highest TTC reduction in root tissue (8.03 O.D. g^(-1)). After 60 and 150 days of treatment, leaf Cl(superscript -) concentration was high for seedlings cultivated in 3.0% NaCl, reaching 78.10 mg g^(-1). Moreover, seedlings grown at 0.75% NaCl showed the highest root Cl(superscript -) concentration. Leaf proline concentrations were high for seedlings cultivated in 0.75 and 1.5% NaCl at day 150, these values were 0.57 and 0.47 μ mole g^(-1), respectively. These results indicated that R. stylosa seedlings could have better physiological viability when grown in mild salinity.