EFFECTS OF SALINITY ON BALDCYPRESS SEEDLINGS - PHYSIOLOGICAL-RESPONSES AND THEIR RELATION TO SALINITY TOLERANCE

Growth and physiological responses of 15 open-pollinated families of b aldcypress (Taxodium distichum var. distichum) subjected to flooding w ith saline water were evaluated in this study. Ten of the families wer e from coastal sites in Louisiana and Alabama, USA that have elevated levels of soil-water salinity. The other five families were from inlan d, freshwater sites in Louisiana. Seedlings from all families tolerate d flooding with water oi low (2 g l(-1)) salinity. Differences in biom ass among families became most apparent at the highest: salinity level s (6 and 8 g l(-1)), Overall, increasing salinity reduced leaf biomass more than root biomass, which in turn was reduced more than stem biom ass. A subset of seedlings from the main greenhouse experiment was per iodically placed indoors under artificial light, and measurements were made of gas exchange and leaf water potential, Also, tissue concentra tions of Cl-, Na+, K+, and Ca2+ were determined at the end of the gree nhouse experiment. Significant intraspecific variation was found for n early all the physiological parameters evaluated, but only leaf concen trations of Na+ and Cl- were correlated with an index of family-level differences in salt tolerance.