study of the yield and growth indices of safflower (carthamus tinctorius l.) as double cropping in yasouj region

in order to study the yield and growth indices of spring safflower as double cropping, an experiment was carried out in 2007 at the research farm of faculty of agriculture, yasouj university, iran. the experiment was a factorial based on randomized complete block design with three replications. factors included of combination of four sowing dates (may 16, june1, june 16 and july 2) and four cultivars (arak 2811, esfahan 14, il111 and pi). results showed that esfahan 14, compared to other cultivars, had the highest grain and biological yields due to higher leaf area index (lai), crop growth rate (cgr), dry matter (dm) and net assimilation rate (nar). thus it might be suggested as appropriate cultivar for double cropping in yasouj. third sowing date produced the highest grain and biological yields relative to others. it appears that cultivars in third sowing date, due to grater lai, probably had more radiation intercept and photosynthesis, so that had the grater cgr and dm and grater seed and biological yield. finally, increasing of above mentioned indices resulted in grater seed and biological yield at third sowing date. maximum nar (10.1 gr m-2leaf day-1) and lai (2.76) were seen at third sowing date. finally, with respect to the results, lai, cgr and dm were the effective indices on seed yield of safflower cultivars.