effect of terminal heat stress on yield and yield components of spring bread wheat in ahwaz

terminal heat stress in mediterranean climates like ahwaz is reduced wheat yield. in order to study effect of terminal heat stress on yield and yield components of 20 spring bread wheat cultivars, an experiment was conducted in ramin university of agricultural and natural resources, ahwaz in 2007-2008. the experimental design was stripe block design in randomized complete block design with three replications. the experimental factors were four sowing dates (6 nov., 6 dec., 5 jan. and 4 feb.) in horizontal plots and 20 spring wheat cultivars in vertical plots. the results showed that sowing date, cultivars and its interaction had significant effect on all experiment traits. means comparisons of interaction effects showed that maximum grain yield (7.039 t/ha) produced by chamran cultivar in sowing date of 6 dec. and minimum grain yield (1.219 t/ha) produced by falat cultivar in sowing date of 4 feb.