the effect of seed priming on germination, stand establishment and yield of wheat (triticum aestivum l.)cultivars in three different climates of iran

poor wheat stand establishment is a major cause of yield loss, particularly in rainfed and poorly irrigated environments. seeds of eight wheat cultivars (triticum aestivum l.) including irrigated and rainfed varieties, belonging to three different climates of iran (hamedan as cold, karaj as temperate and sarpolzohab as warm climates) were primed using osmoprimig treatments through use of urea , nacl and peg6000 as well as hydropriming treatments through tap and distilled water. in each climate while employing the related cultivars, a separate experiment was conducted using a split plot factorial in a randomized complete block design of three replications. main plots were representatives of two sowing dates (timely, and late), while subplots included combinations of cultivar and priming treatments. results showed that urea and peg osmopriming treatments as well as tap water hydropriming treatments caused an increase in emergence rate (both two sowing dates) in all rainfed cultivars of all climates as well as in alvand irrigated cultivar of cold climate (hamedan) zone. in addition, nacl and urea osmopriming increased flowering speed in first sowing date of azar2 (rainfed cultivar of hamedan) and chenab (rainfed cultivar of sarpolzohab) respectively. in rainfed cultivars of cold climate zones, peg and urea osmopriming significantly increased leaf area index. number of spikes per unit area was the most important factor among yield components that was significantly increased by osmopriming treatments in hamedan cultivars (both irrigated and rainfed cultivars) as well as in karaj rainfed cultivar and for both sowing dates. this resulted in an increase in yield. meanwhile harvest index was not affected by priming treatments. it seems that the desired effects of osmopriming would be on the increase in the presence of such environmental growth limiting factors as low temperatures and water deficit.