Seven sugarcane (Saccharum sp.) commercial cultivars, viz., , originally derived from meristem cuttings were subjected to simulated osmotic stress (as 200 mM mannitol) under controlled environmental conditions. Proline content in the leaf tissues of all cultivars except K92-80, increased in plants subjected to mannitol-induced osmotic stress. Chlorophyll a (Chl a ), chlorophyll b (Chl b ), total chlorophyll (TC), maximum quantum yield of PSII (F v /F m ), and photon yield of PSII (Φ PSII ) of all seven cultivars decreased under osmotic stress resulting in a reduction in net-photosynthetic rate (P n ). A positive correlation was found between F v / F m and Φ PSII , proline content and non-photochemical quenching (NPQ), Φ PSII and P n , and P n and plant dry weight in the sugarcane cultivars. Based upon Ward's multivariate cluster analyses of data for proline content, photosynthetic capacity, chlorophyll fluorescence, and growth inhibition, three cultivars (K88-92, K92-80 and UT-94-2-483) were identified as water deficit sensitive, whereas four (K84-200, K95-84, K97-32 and LK92-11) as water deficit tolerant. These observations on different cultivar's sensitivity/tolerance were confirmed by growth and yield attributes measured in a field trial. The plant dry weight (in vitro) correlated positively with total stalk weight of sugarcane cultivars