Evaluation of the effect of different fertilizer treatments on yield and some reproductive traits of Saffron (Crocus sativus L.) in the climatic conditions of Ardabil

Proper management of fertilizer is one of the necessary means in order have a stable and lucrative agro-ecological system in saffron. Therefore this research was conducted with the aim of investigating the effect of different fertilizer sources on quantitative and qualitative yield of saffron as one of the most favored plants as split plots in randomized complete block design with three replication during two growing years of 2015- 2016 and 2016 -2017. Experimental treatments consisted of three levels of organic fertilizer: manure, vermicompost and control in the main plots, combination of chemical fertilizer of nitrogen and phosphorus (NP) which was used in two levels of 50 and 100% of fertilizer recommendation in sub plots. Five levels of growth-promoting bacteria including non-insemination (control), inoculation with Azotobacter PTCC 1658 (Azotobacter chorococum), Pseudomonas aeroginosa, Bacillus subtilis and the combination of growth-promoting bacteria (Azotobacter chorococum + Pseudomonas aeroginosa + Bacillus subtilis) in sub-sub plots. The results showed that the combined application of growth-promoting bacteria significantly increased the number of flower by 92% and the yield components of stigma and style by 77%, compared to the control. Also, the use of growth-promoting bacteria in combination with organic fertilizers had the most significant effect on stigma length. Also, the result of Mean comparison showed that, the treatment of 100% of chemical fertilizer had the highest sitigma length (3.67 cm) with a significant difference compared to the treatment of 50% of chemical fertilizer requirement (3.45 cm). The use of organic fertilizers along with the combination of bacteria had the greatest effect on the percentage of crocin. The findings of this study showed that the combined application of growth-promoting bacteria with organic fertilizers had the highest dry yield of stigma and style, with 2.82 kg / ha.