Response of quantitative and qualitative characteristics of Saffron flower to the last irrigation cut-off time and various fertilizer resources

In order to evaluate the effect of last irrigation cut-off time and various fertilizer resources on quantitative and qualitative characteristics of Saffron (Crocus sativus L.) flower, an experiment was conducted in a split-plot arranged as a randomized complete block design with three replications and 18 treatments in a four year research farm of Jihad ministry located in Lalezar village, Bardsir region, Kerman province, in 2015-2016. The experimental treatments were irrigation cut-off time (conventional time (5 May), 15 days before the conventional time (20 April) and 15 days after conventional time (20 May)) assigned to the main plot, and nutritional resources (cow manure 40 t ha-1, hen manure15 t.ha-1, vermicompost 10 t ha-1, humic acid 2 kg ha-1, and chemical fertilizer containing 200 kg ha-1 urea and 140 kg.ha-1 P and K) as subplot. The analysis of variance results showed that the effect of irrigation cut-off treatment was significant on all the quantitative traits, but the treatment had no significant effect on qualitative traits of flower. The results showed that the delay in irrigation cut-off led to a significant decrease in other traits. As, the highest number of flowers (41.10 in m-2), fresh (145.16 kg.ha-1) and dry (19.41 kg.ha-1) weight of flower, fresh (11.12 kg.ha-1) and dry (2.02 kg.ha-1) weight of stigma were found in the earlier irrigation cut-off treatment (before the conventional time). The effect of fertilizer resources on all the studied traits was significant except for the values of picrocrocin and safranal. In all the irrigation treatments, vermicompost and cow manure significantly produced higher flower number and stigma yield than other fertilizer treatments. Dry stigma yield in chemical fertilizer (1.91 kg.ha-1), hen manure (1. 57 kg.ha-1) and humic acid (1.42 kg.ha-1) was significantly higher than control (1.26 kg.ha-1). The highest (169.7 nm) and lowest (163.1 nm) amount of crocin were obtained in control and vermicompost treatments, respectively. In general, the results showed that irrigation cut-off in April with using vermicompost fertilizer had the best conditions for saffron cultivation in the Bardsir region of Kerman.