Effects Of Drought Stress And Plant Density On Ecophysiological Traits Of Three Safflower Lines In Summer Planting In Isfahan

In order to study the ecophysiological traits of safflower in different intensities of drought stress in summer planting, three safflower lines selected from Isfahan landraces (Isfahan-8, Isfahan-24 and Isfahan-44) in three plant densities (31, 20 and 13.3 plant/m2) with four irrigation regimes (three irrigations after 70,140 and 210 milimeter evaporation from class A pan up to physiological maturity and one after 140 milimeter evaporation up to complete flowering) were used in north-west of lsfahan. The experiment was carried out in northwest of Isfahan in a rondomized complete block design with a splitsplit plots layout in three replications during 2001 and 2002. Stress intensity (SI) was calculated and the effects of drough stress on some ecophysiological characters such as grain water use efficiency (GWUE), biomass radiation use efficiency (BRUE), grain radiation use efficiency (GRUE), oil radiation use efficiency (ORUE), leaf area index (LAI), specific leaf area (SLA) and plant damping off rate (PDR) were evaluated. The results showed that reduction in water use in canopy (lower than after 70 milimeter) resulted in an intensive stress in canopy of sofflower (SI was about 0.45 and 0.42 in 2001 and 2002, respectively in irrigation after 140 milimeter treatment). With more decreased water use, increase of stress intensity was very little. Drought stress reduced GWUE, BRUE, GRUE, ORUE, LAI and SLA, but PDR was increased.