WE PRESENT here the comparative protective potentiality ofexogenously applied validamycin A, a potent inhibitor of
trehalase as seed soaking prior to sowing in saline soil with salinitylevel (EC 10.06 dS/m) in mitigating NaCl toxicity and inducingsalinity tolerance in two rice (Oryza sativa L.) cultivars (cv.), Sakha103 (salt-sensitive) and Agami M5 (salt-tolerant). Salinity stressdecreased starch and total soluble protein contents concomitantly withincreasing total soluble sugars, proline and free amino acids in bothcultivars. Validamycin A decreased the activity of trehalase whichleads to the accumulation of trehalose in both cultivars of rice plants.Raising trehalose level in the plant tissues was accompanied byincreasing the starch and protein content and appearance of newprotein pattern of both cultivars. Application of validamycin Aincreased grain yield, 1000-grain weight and filled-grain percentagefor both rice cultivars under saline field conditions. Soaking rice seedswith 30μM of validamycin A could alleviate the harmful effects ofsalinity stress.