Abstract: In a 2-year experiment, 187 genotypes were grown under well-watered and drought stress conditions, imposed at panicle initiation stage. The relationship of genotypic variation in yield under drought conditions to potential yield, heading date and flowering delay, reduction in plant height, and to a drought response index (DRI) was detected. Grain yield under drought stress conditions was associated with yield under well-watered conditions (r = 0.47**, and r = 0.61** during 2 years of tests). The delay of heading date ranged from –1 (no delay) to 24 days, and was negatively associated with grain yield (r = –0.40*), spikelet fertility percentage (r = –0.40**), harvest index (r = –0.58**), but positively associated with yield reduction percentage (r = 0.60**). The reduction in plant height was negatively associated with grain yield (r = –0.24**, and r = –0.29**), spikelet fertility percentage (r = –0.23**, and r = –0.21*), harvest index (r = –0.37**, and r = –0.54**), and positively associated with yield reduction percentage (r = 0.58**, and r = 0.58**) in 2003 and 2004, respectively. The DRI of genotypes was strongly associated with grain yield (r = 0.87**, and r = 0.77**), fertility percentage (r = 0.66** and r = 0.54**), harvest index (r = 0.67** and r = 0.61**), and negatively associated with grain reduction percentage (r = –0.70**, and r = –0.73**) under drought stress. The results indicate that genotypes with drought resistance can be identified by measuring yield potential, delay in flowering, reduction in plant height, or DRI under test environments of well-watered and drought stress.

Key words: delay in heading date, drought resistance, drought response index, Oryza sativa, reduction in plant height, yield potential.