wheat (triticum aestivum l.) growth and yield as influenced by flooding and salinity stresses in northern iran

salinity and flooding are as two very important factors of soil degradation. they often occur together and cancause severe damage to plants. however, plant response to environmental stresses may vary with growth stage atwhich exposure occurs. a pot study was conducted in 2005-2006 in northern aq qala (northern iran) to studycombine effects of waterlogging and soil salinity at different growth stages on grain yield and some yield componentsof two iranian spring wheat genotypes, i.e. kouhdasht and tajan. two salinity treatments were applied, viz. a nonsaline(ece = 3 ds m-1) and saline soil (ece= 10 ds m-1). the six waterlogging treatments within each set consistedof: control (no waterlogging), and waterlogging applied at tillering (t); stem elongation (se); booting (b); grainfilling (gf); and two spells of waterlogging, i.e. at tillering and grain filling stages (t+gf). in this experiment,waterlogging was imposed by keeping pots in hypoxia conditions by adding water daily (during up to two weeks) to110% of available water holding capacity. results reveal that highest reduction in grain yield; thousand grain weight(tgw) and harvest index (hi) were observed through waterlogging at t+gf for both wheat genotypes. nonsignificantchanges in grain yield, tgw and hi were observed via waterlogging at b as compared to control.kouhdasht showed better performance than tajan under saline and saline × waterlogged conditions