Effect of salt stress during early seedling growth on phenology and yield of spring wheat

Grain yield potential of wheat (Triticum aestivum L.) can be markedly affec ted by environmental stresses that occur early in the life cycle of the cro p. This study was conducted in greenhouse sand cultures to determine the ef fects of salinity either applied or withdrawn at three different stages of wheat shoot organogenesis: (l)late in the leaf primordium initiation phase (LLPI), (2) double ridge stage DRS), or (3) terminal spikelet formation(TSF ). Plant response to changes in salinity was evaluated in terms of mainstem phenology, timing of tiller appearance, yield, and yield components. Leaf primordium initiation was more sensitive to changes in salinity than was sp ikelet primordium initiation. For changes in salinity at LLPI, final mainst em leaf number was controlled by the new, rather than the original, stress level, whereas when salinity was changed at DRS, final spikelet number was controlled by the original salinity level. Changes in salinity level did no t inhibit tiller bud initiation, but affected the timing of tiller emergenc e. Grain yields were reduced by relatively brief periods of salinity, but l osses were minimized if stress was withdrawn at LLPI or DRS or if stress ap plication was delayed until TSF.