The plant growth, net photosynthetic rate (PN), intercellular CO2 concentration (ci), and dry matter production of Ceriops roxburghiana Arn. were significantly increased with increasing salinity from 0 to 400 mM NaCl. At 600 mM NaCl, shoot and root lengths, and dry mass were significantly depressed with respect to control. Absence of diurnal fluctuation of concentrations of organic acids, and the low activity of phosphoenolpyruvate carboxylase and high activity of ribulose-1,5-bisphosphate carboxylase confirmed the operation of C3 pathway in Ceriops even at increasing salinity. and A. Rajesh, R. Arumugam, V. Venkatesalu.
The activities of the whole chain electron transport and photosystems 1 and 2 in isolated chloroplasts of Sesuvium poríulacastrum L. (a halophytic herb) increased with concentrations of NaCl (100 to 600 mM), and declined at high NaCl concentrations (600 to 900 mM).
Sodium chloride (NaCl) concentratíons 200 to 900 mM enhanced the photosynthetic rate (Pn) both in whole leaves and in mechanically isolated, intact mesophyll cells of a salt marsh halophyte Sesuvium portulacastrum wilh a maximum at 600 mM NaCl. These changes were in agreement with changes in chlorophyll concentration in leaves. Though the increasing salt concentratíons resulted in leaf succulence, no change in the photosynthetic carbon pathway was observed.
Sodium chloride salinity had enhanced the photosynthetic rate, photosystem 2 activity and chlorophyll synthesis in isolated leaf cells of Ipomoea pescaprae up to 200 mM NaCl. The salt treated plants did not show any shift in the mode of photosynthesis.
The mangroves Rhizophora lamarkii, Ceriops roxburghiana, Bruguiera gymnorrhiza, Aegiceras corniculatum, and Lumnitzera racemosa were screened for their carbon metabolic pathways by measuring net photosynthetic rate (PN), 13C discrimination rate, leaf anatomy, titratable acidity, and activities of phosphoenolpyruvate carboxylase, NADH-malate dehydrogenase, alanine aminotransferase, aspartate aminotransferase, and pyruvate phosphate dikinase. The tested mangroves had a well developed succulence, opening of stomata during day time and closure in the night hours, and absence of diurnal fluctuation of organic acids in their leaves which excludes the possibility of these species being CAM plants. Moreover, the leaf anatomy had not exhibited Kranz syndrome. The high values of discrimination against 13C, low PN, high CO2 compensation concentration, and the activities of aminotransferases in the direction of alanine formation suggest that the species may follow C3 mode of carbon metabolic pathway. and V. Venkatesalu ... [et al.].