effects of azospirillum lipoferum on seedling characteristics derived from sunflower (helianthus annus l.) seed water deficit conditions

seedling characteristics of different sunflower (helianthus annus l.) cultivars under drought stress and inoculation with the azospirillum lipoferum in a spilt-factorial layout based on randomized complete block design with three replications were evaluated. treatments included dehydration stress (seed produced on maternal plants which irrigated after 60 (desirable irrigation), 120 (medium stress), 180 mm (severe stress) evaporation from evaporation pan class a), different sunflower cultivars (lakomka, master, favorite, soor and armavirosky) and inoculation with bacteria (azospirillum lipoferum and control). bacteria allocated in the main plots and seeds which derived from dehydration stress conditions and different cultivars were allocated in sub plots as a factorial layout. results showed that the time of seedling emergence, seedling vigor index, leaf petiole, stem and seedling dry weight were increased 14, 44, 30, 31, 22 and 27 percent by inoculating with bacteria, respectively. the percent of seedling emergence of seeds derived from medium stress 48 percent was more than optimal irrigation conditions. final appearance, speed of emergence, emergence index, dry weight and stamina seedling resulting from severe stress conditions were decreased compared with optimal irrigation. seedling emergence of seeds derived from medium stress which inoculated with bacteria increased by 9 percent. emergence speed index, appearance, stamina and seedling dry weights of seeds which inoculated with bacteria increased at medium and sever water stress. with consideration of the effect of dehydration stress on germination and seedling emergence, seed inoculation with bacteria improved seedling emergence and seedling vigor of seeds derived from dehydration stress conditions.