Effect of biological and chemical fertilizers on stigma yield and quality of saffron (Crocus sativus L.) in climatic conditions of Ardabil

Biofertilizers are promising in sustainable agriculture as an alternative to chemical fertilizers and increase soil fertility and plant growth. In this study, effects of chemical and biological fertilizers (PGPR) on quality and quantitative traits of saffron were evaluated. A field experiment was conducted as split plots arrangements using randomized complete block design with three replications at Research Farm of Ardebil Agricultural Research Center, Iran during two growing seasons of 2015-2016 and 2016- 2017. Experimental factors were chemical fertilizers NPK (50 and 100% of required chemical fertilizers) assigned to the main plots, and plant growth promoting rhizobacteria including Azotobacter Chrococum Sp, Pseudomonas aeruginosus, Bacillus subtilis and their combination and control treatment randomized subplots. The results indicated that bio- and chemical fertilizers significantly increased flower and stigma length, dry yield of style and stigma and quality traits such as crocin, picocrocin and safranal conetnts as compared with controlApplication of 50% of required chemical fertilizer with application of combined biofertilizer (A. Sp., P. aeruginosus and B. subtilis) increased dry yield of stigma and style by 57% when compared with control. Also, the same treatment increased picocrocin, safranal and crocin contents with 44, 62 and 47 percent, respectively, in comparison to control. The length of flower and stigma were increased by application of combined bio-fertilizers up to 3.32 and 1.63 cm, respectively, in comparison with control. In conclusion, application of bio-fertilizers can reduce the use of chemical fertilizers and it can be a sutable ecological strategy for achieving sustainable agriculture and reducing environmental effects.