Effects of organic fertilisers and mother corm weight on yield, apocarotenoid concentration and accumulation of metal contaminants in saffron (Crocus sativus L.)

Abstract

The effects of two factors that determine the quality and quantity of saffron yields, i.e. organic fertilisers, including i) humic acid (Humax®), ii) organic-mineral emulsion (Omic®), iii) cow manure, and iv) unfertilised control, and mother-corm weight (using corms of 0.1–4 g, 4.1–8 g and 8.1–12 g) were investigated by measuring yield-related traits of saffron in 2 years. In the first year, the application of organic fertilisers had no significant effect on most of the studied traits. In the second year, the highest rate of increase in the stigma-style dry weight yields, with 55.5 mg day−1, was recorded for the cow manure treatment. In both years, the style-stigma yield was significantly higher in the treatments with large mother-corms compared with small mother-corms, with large differences especially in the first year, indicating that the benefit of planting heavier mother-corm was related to the stage of the production cycle. In accordance with INSO (Iran National Standard Organisation), the concentrations of crocin and picrocrocin in all treatments were within the range of Grade I and II saffron, respectively. The concentrations of the major metal contaminants (arsenic, lead and mercury) were much lower than the permissible limits in all treatments, indicating that none of the tested organic fertilisers caused pollution of the saffron.