Study of drought tolerance in four wheat genotypes, at germination stage

Wheat is the most important crop worldwide, which may experience drought stress germination and grain filling period. Effects of drought stress at these stages reveal at the same season and at the future crop season respectively. In order to evaluate the effects of drought stress on seed vigor, a laboratory experiment was conducted using a factorial arrangement in a randomized completely design with three replications during 2008. The factors consisted four genotypes (Pishtaz, Marvdasht, DN-11, and WS-82-9) and five water potential (zero, -0.3, -0.6, -0.9 and -1.2 MPa). Results showed that genotypes, drought stress levels and their interactions, have significant effects on length, fresh and dry weight of radicle and plumule, also with reducing water potential all measured traits were decreased, but this reduction, was greater in plumule than radicle. These different responses caused higher Root/Shoot ratio. Also germination percent decreased more than germination rate due to drought stress. Although tolerance to water stress at grain filling period somewhat decreased seed vigor, but there wasn’t any relationship between drought tolerance at germination stage with terminal drought stress tolerate. Among these genotypes, Pishtaz and DN-11 tolerated to drought stress, Marvdasht and WS-82-9 were intermediate and sensitive to water stress at germination stage respectively.