Effect of drought stress in different importance stages. There are different types of drought develop in rice. According on the cereal species, for especially rice plant, and on variously geographical locations of plant cultivation. drought stress may occur any times during growth of the vegetative transition in the shoot apical meristems and an appropriately leaded to match of the pattern of inflorescence development and the time of flowering to the temporal variation in water availability is recognize as one of the most important trait conferring adaptation to drought (Barnabas et al., 2008). Water deficit affects grain yield of rice in various ways depending on the degree. duration and timing (o'Toole and Moya. 1981). It is less damaging during the vegetative than the reproductive stage. as young plants are able to recover when stress is The most sensitive period is during relieved the reproductive stage (Cruz and O'Toole. 1984).