The Response of Morphology, Yield and Yield Components of Spring Safflower Genotypes to Different Sowing Dates

In order to study the response of morphology, yield and yield components of spring safflower (Carthamus tinctorious L.) cultivars to different sowing dates, an experiment was carried out using a split-plot design on the basis of a randomized complete block design with four replications, in Agricultural Sciences and Natural Resources University of Khouzestan, south-west of Iran at 2016-2017. Experimental factors were four sowing dates (11 November, 2 December, 5 January and 3 February) in main plots and five safflower cultivars (Sina, Goldasht, Soffeh, local Esfahan (Kooseh) and Faraman) in sub plots. The analysis of variance showed that the interaction effect of sowing date and cultivar was significant on all measured traits except plant height and grain oil percent. The mean comparisons showed that the highest grain yield (3722 kg/ha) and oil yield (837 kg/ha) were produced in sowing date of 11 November by Goldasht cultivar, and the lowest grain yield (351 kg/ha) and oil yield (71 kg/ha) were observed in sowing date of 3 February by Faraman cultivar. The highest amount of measured traits were achieved in the first sowing date (November 11) and  delays in sowing date and, hence, occurrence of a terminal heat stress in flowering and grain filling phase decreased the grain yield and oil yield