in this study the effects of source limitation on grain yield of twelve barley cultivars (‘aras’,‘jonub’,‘reihan’,‘zarjou’,‘sararoud’,‘sahra’,‘fajr30’,‘karoun’,‘gorgan’,‘makouei ’and ‘nosrat(’ under post anthesis water deficiency were studied. source limitation treatments were included that control, removing of awn, leaves below flag leaf, flag leaf and spike photosynthesis. all source limitati...