Effect of fertilization pulses on the production of Gracilaria birdiae seedlings under laboratory and field conditions

The genus Gracilaria is one of the most important sources of agar in the world. In Brazil, Gracilaria birdiae is the main commercially exploited species; however, overexploitation has contributed to the depletion of natural beds. In order to obtain more information so as to consolidate G. birdiae cultivation, studies under laboratory (indoor and outdoor) and field (sea and shrimp pond) conditions were conducted to evaluate the effects of fertilizer pulses on biomass and relative growth rate (RGR) of this species. The following nutrient sources used were (T 1 ) shrimp-pond effluent, (T 2 ) fertilizer for aquarium plants (Mbreda), and (T 3 ) fertilizer extract of Ascophyllum nodosum (Acadian). Significant differences for growth were recorded over time for all treatments in both outdoor and field conditions ( p