Evaluation of growth and yield of safflower cultivars in different planting dates

In order to evaluate growth and yield variations of safflower (Carthamus tinctorius L.) in different planting dates, a factorial experiment with four replications was conducted at University of Birjand, Iran. Three spring cultivars of safflower, including a local variety (Isfahan) with two foreign cultivars (Gilla and CU1) were sown at 4 and 19 Apr. and 4 May. Results showed except height of first branch, other morphological characteristics were affected by planting dates. The node number, height of first branch, and length of internodes varied considerably between cultivars, with a constant response of cultivars in different planting dates. The total and fertile capitula were not differing between cultivars, but Isfahan had the most kernels per capitulum with the lowest kernel weight and CU1 showed just the reverse response. Earlier planting date lead to more produced and fertile capitula, and formation of more kernels in secondary capitula, with the highest produced and fertile capitula for Gilla, the highest total kernel per capitula for Isfahan, and the highest kernel weight for CU1, especially in the first planting date. The stem height and diameter and branches numbers showed high correlation with seed yield; however, number of primary capitula showed the highest correlation with yield and was accounted for 90 percent of yield variation. According to these results, planting Isfahan variety at the first possible time, due to its nativeness and high adaptation to this arid climatic zone, provide an opportunity for producing higher yields in comparison with foreign cultivars. Keywords: Carthamus tinctorius, spring cultivation, yield components, planting dates