The photosynthesis and chlorophyll a fluorescence in seedlings of Kandeliacandel (L.) Druce grown under different nitrogen and NaCl controls

Kandelia candel (L.) Druce is the dominant mangrove species on the west coa st of northern Taiwan, We have measured the net photosynthetic rate (PN) an d chlorophyll (Chl) a fluorescence of seedlings grown at combinations of tw o nitrogen (0.01 and 0.1 mM) and two NaCl (250 and 430 mM NaCl) controls. W ith the same nitrogen level, seedlings grown at higher salinity (HS) had a significantly lower PN and stomatal conductance (g(s)) than those at lower salinity (LS). An increase in nitrogen availability significantly elevated P-N and g(s) of the LS-grown seedlings. Compared to dark adapted leaves, th e maximum quantum yield of photosystem 2 (PS2) (F-v/F-m) of leaves exposed to PFDs of 1200 and 1600 mu mol m(-2) s(-1) for 2 h was significantly reduc ed. The degree of F-v/F-m reduction differed among leaves of the four types of treated plants. Chl fluorescence quenching analysis revealed difference s among the examined plants in coefficients of non-photochemical and photoc hemical quenching.