Effect of plant density and K, Zn elements on morphophysiological and yield of safflower cultivars

Determining cold stress tolerance is very important for the successful introduction of the cultivars at cold region. A field study was conducted to determine the effects of plant density, K and Zn fertilizer on tolerance, morphophysiological responses, yield and yield components of two safflower cultivars under cold region. The experiment was conducted in research farm of Agriculture College of Shahrekord University during 2007-2008. The factorial set of treatments arranged within a randomized complete block design with three replications. Treatments including Pi and Zarghan cultivars and plant densities (30, 40 and 60 plant m-2) and three type of fertilizers (Potassium, Zink and control). The results obtained showed significant differences between traits in all treatments. The highest survival plants, laef area index and plant height with 84.5, 3.3 and 23.1 Cm were belong to Pi cultivar. The highest Photosynthetic and transpiration rates with 26.5 and 13.8 µmol cm-2 s-1 was obtained from potassium treatment. The highest survival plants after freezing and cold stress (over wintering) (90.2%), the highest leaf area index (3.8), plant heights (87.4cm) were obtained from Pi cultivar, K and 60 plant m-2. Photosynthetic (26.5 µmol cm-2 s-1 ) and transpiration rates (13.8 µmol cm-2 s-1 ) were highest in Pi cultivar, K and 30 plant m-2. In Pi cultivar, K and 30 plant m-2 branches plant-1 (5.2), seed head-1 (33.3), 1000 seed weight (30.1g) were highest. The highest of biological yield (14368 kg), seed yield (3768 kg) and harvest index (25.8%) were belong to Pi cultivar, K and 60 plant m-2. The result showed plant survival and cold tolerance of Pi cultivar improved by K and Zn fertilizer that promoted the growth of safflower cultivar and can affect morphophysiological responses, yield and yield components (branches plant-1, seed head-1, 1000 seed weight) after freezing and cold conditions.