This study investigated intra-specific variation in the growth parameters and photosynthetic rates of individual attached leaves of sugar beet (Beta vulgaris L.) plants during salinisation. Sugar beet plants grown in sand culture were gradually exposed to different levels of salinity (0, 50, 150 , 250 and 350 mM, NaCl + CaCl2 in 5:1 ratio). Although growth parameters such as leaf area and dry matter accumulation were stimulated or unaffected at low level of salinity (50 mM), higher salt concentrations significantly decreased all growth traits. At high level of salinity, cv P29 showed a significantly higher leaf area and total dry matter than others at 8 weeks of salt treatments. Net photosynthesis (ACO2) was plotted against computed leaf internal CO2 concentration (Ci), and the initial slope of this ACO2-Ci curve was used as a measure of photosynthetic ability. Leaves from plants exposed to 50 mM salinity showed little change in photosynthesis, whereas those treated to high level of salinity had up to 91.5 % inhibition, with increae in CO2 compensation point. Leaves appeared healthy and leaf chlorophyll content increased with increasing salinity. Although partial stomatal closure occurred with salinisation, reductions in photosynthesis were partly non-stomatal at high levels of salt treatment. Photosynthetic ability was inversly related to the concentration of either Na+ and Cl- in the leaf laminas sampled at the end of experimental period. Key Words: Gas Exchange, Photosynthesis, Growth, Sugar Beet, Salt Stress

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