effect of water deficit on water use efficiency of canola (brassica napus l.) cultivars in mashhad condition

water deficit is a major factor influencing yield of canola (brassica napus l.) seed yield and oil content. a field experiment was conducted during 2010 growing season in the agriculture research station of torogh, mashhad, iran to evaluate responses of canola cultivars to limited water. experimental design was rcbd pattern with three replications. treatments were two irrigation regimes (based on irrigation after 120 mm evaporation on class a pan for stress treatments and 80 mm evaporation for non stress treatments) and six rapeseed cultivars(hyola 401, hyola 330, parkland, goldrush, bp18 and landrace). results showed that water use efficiency was significantly affected by drought stress. average of water use efficiency at all cultivars in stress treatments was 6.6 kg per m3 water by 3412.3 m3 water used and 4.5 kg per m3 water by 4612.3 m3 water used in non stress treatments. the highest and the lowest water use efficiency observed in hyola 401 and goldrush by 7.4 and 2.6 kilograms per m3 water in drought stress treatment, respectively. in addition to the ability of oil production by rapeseed cultivars under drought stress was affected and became less in drought stress. hyola 401 had the highest oil content by 0.28 kg oil per m3 water in non stress and bp.18 had the lowest oil content 0.06 kg oil per m3 water in stress treatment. results showed that water deficit can affect oil content significantly.