Effect of salinity on water use efi¬ciency and dry matter production of guava plants. To study the salt tolerance of guava cultivars (Psidium guajava I L.cvs RS 980 and Cimpa 00916), the effect os salinity on growth, dry matter production and agronomic water use efi¬ciency were evaluated. Seedlings were grown in a glasshouse experiment in 3-1 post i¬lled with soil in Tunja, Colombia. Plants were exposed to either non-saline (ECe: 1.2 dS.m -1 ) or saline conditions using 20, 40, 60 and 80 mM NaCl based to air dry soil (ECe: 3.0, 5.4, 7.9 and 10.5 dS.m -1 respectly of a saturated soil extract) 3 months after germination. Plants were harvested 7 months after the NaCl exposure. The evapotranspiration rate (cm 3 ), dry matter production (g), agronomic water use efi¬ciency (g1 -1 ) and leaf area (cm 2 ) of both cultivars was reduced by salinity. Dry matter partitioning in roots shoot and leaves and root: shoot ratio based on dry matter were little affected by salinity. In comparison to the control plants, the agronomic water use efi¬ciency was reduced 29.5% in cultivar RS 980 and 10.0% in Cimpa 00196 by 80 mM NaCl; similarly, 80 mM NaCl reduced the total dry matter production 50.8% in RS 980 and 29.8% in Cimpa 00196 in comparison to the control plants. Thus, it appears that RS 980 was more salt-sensitive than Cimpa 00196.