Effect of rate and time of nitrogen application on grain yield and its components in spring safflower (Carthamus tinctorious L.)

This experiment was carried out for evaluation of the effect of rate and time of nitrogen application on grain yield and yield components in spring safflower in Shirvan-Chardavol in Ilam during 2002-2005 cropping seasons. Experimental treatments were arranged as factorial in complete randomized block design with three replications. Nitrogen rates (50, 75, 100, 125 and 150 Kg.ha-1) and split application of nitrogen in three levels (first split: 50%: 50% ratio at pre-planting and late rosett, second split: 50%: 50% ratio at preplanting and early flowering and third split: one-third: one-third: one-third ratio at pre-planting, late rosett and early flowering). Combined analysis of variance indicated that interaction of nitrogen rate × split application was significant (p<0.05) on grain yield. Mean comparison showed that 100 Kg.ha-1 of nitrogen with triple splitting application at pre-planting, late rosett and early flowering stages produced higher grain yield (2752 Kg.ha-1). This was achieved due to increase in head/m2 (240 heads), grain/head (36.3 grains), and 1000 grain weight (34.4 g). Application of 100 kg.ha-1 nitrogen and its triple splitting produced the highest oil yield (755 Kg.ha-1).