Effects of four types of growth regulators on yield, photosynthetic pigments and qualitative characteristics of saffron (Crocus sativus L.) under greenhouse conditions

In order to investigate the effects of growth regulators on yield and agronomical characteristics of saffron (Crocus sativus L.), an experiment was conducted in a randomized complete block design in the research greenhouse of Faculty of Agriculture, University of Zanjan. Experimental treatments included corms priming with gibberellic acid (GA) (250, 500 and 750μM), salicylic acid (SA) (700, 1400 and 2100μM), paclobutrazol (PBZ) (50, 100 and 150μM), chlormequat chloride (CCC) (500, 1000 and 1500 μM), hydropriming (HP) (distilled water), and control (treatment without any growth regulator). Among the treatments, the effect of GA was more pronounced than other growth regulators, so that the highest dry yield of flower and stigma was observed in GA treatment, especially at 500-μM level. CCC and PBZ caused the lowest flower and stigma yield and the highest amount of chlorophyll pigments compared to other treatments. In contrast, the use of GA and SA reduced the chlorophyll content. HP treatment did not show any significant difference with control. SA treatment increased safranal (perfume) and crocin (color) of the stigmas. The highest effect on picrocrocin (flavor) was obtained in CCC treatment.