Seasonal variation of agar and two plant hormones in Macroalgae Gracilaria corticata (Rhodophyta)

Red seaweeds contain compounds such as agar and hormones that have many uses in industry. This research was done to determine biomass and extract two hormones and agar from Gracilaria corticata algae. Methods Sampling was done from December 2014 to November 2015 in Bushehr port, one month apart. Biomass and environmental parameters were measured and algae harvested in the selected transect. After the extraction steps, hormones are separated by the HPLC method and identified by standard injection. The highest amount of agar occurred in July with 63.3%, Zeatin in September with 21.9% and indole butyric acid with 19.21% in January. The highest fresh weight of this algae was measured in March at 423.33 grams per square meter. The results of the ANOVA and Chi-squared statistical tests showed a significant difference in 6 months of sampling in all samples (P<0.05). The amount of agar showed a significant correlation with the biomass. Also, among environmental factors, agar was correlated with salinity and temperature. Butyric indole of acid in January caused the growth of alga, but Zeatin did not show a significant effect on the growth of this species. In general, in order to extract these materials, harvesting can be done in the months that have the highest amount. Considering the exorbitant price of these hormones and the need to use them in algae extracts and algae liquid fertilizer, this research is a starting point for extracting all kinds of hormones from these algae.