Evaluating the Effects of Growth Promoting Fertilizer Containing Seaweed Extract and Mother Corm Weight on Antioxidant Activity and Stigma Quality of Saffron

Algae are usually aquatic photosynthetic organisms that sequester CO2 in their biomass. They are rich in organic matter and nutrients, and thereby can be used in agriculture as an organic fertilizer. Their application will lead to the production of healthy and qualitative foods. To the best of our knowledge, so far the effect of application of marine algae has not been evaluated on saffron qualitative parameters. Therefore, the aim of present study was to investigate the effect of algae in different levels of mother corm weight on qualitative indices of petals and stigmas in saffron.

To investigate the effect of growth promoting fertilizer containing seaweed extract and mother corm weight on qualitative parameters in petals and stigmas of saffron (Crocus sativus L.), an experiment was conducted at Research Field of College of Agriculture at University of Birjand in 2017. The experimental factors included seaweed extract (0, 15 and 30 l ha-1) and corm weight [0.1-4 (small), 4.1-8 (medium) and 8.1-12g (large-sized)], which were tested in a RCBD with three replications.
 Results

The use of algae extract had a significant effect on the petal yield, carotenoid content and antioxidant activity of petals (antioxidant and anthocyanin content) and quality of stigma (picrocrocin, safranal and crocin content). The highest amounts of dry petal yield (0.027 g plant-1), carotenoid content (1.83 mg g-1 FW), anthocyanin (24.49 mg 100g-1 DW), antioxidant (29.80%), safranal (42.43), crocin (198.78) and picrocrocin (74.57) were obtained when seaweed extract was used at the rate of 30 l ha-1. However, no significant difference was found between the two levels of algae extract in terms of all mentioned parameters. The lowest values of petal yield (0.023 g plant-1), carotenoid (1.04 mg g-1 FW), anthocyanin (22.29 mg .100 g DW), antioxidant (25.54%), safranal (40.61 λ), crocin (176.64 λ ), and picrocrocin (72.60 λ ) were obtained from control treatment. Mother corm weight also exerted a significant effect on antioxidant activity, petals anthocyanin content and safranal content in stigma and the highest of them were gained when large-sized mother corms were planted. The interaction effect of experimental factors was not significant on measured parameters.

Overall, the results of this study indicated the beneficial effects of seaweed extract on improving biochemical traits and effective ingredients, which is appropriate for organic production of saffron. The positive role of algae on plants is related to providing micro- and macro-nutrient as well as production of biologically active biotical substances against plant-infecting pathogens. In addition, they have a significant role in improving soil physical and chemical properties, which lead to better growth and development of the plants. Better quality of saffron produced from larger mother corms may also be related to more nutrient reservoir in such corms.