Evaluation of Substrate and Nutrient Management Effects on Halophyte Cultivation: Salicornia bigelovii, Sesuvium portulacastrum, and Batis maritima

Halophyte crops offer a promising solution for food production and nutrient recovery in salt-affected coastal environments where conventional agriculture is increasingly constrained; yet, the cultivation performance of edible halophytes remains strongly influenced by the substrate configuration and nutrient management. This study evaluated, across three sequential experiments, how the substrate type (shallow floating raft versus expanded clay beads) and nutrient regime were associated with biomass production and allocation in three halophyte species, Salicornia bigelovii (glasswort), Sesuvium portulacastrum (sea purslane), and Batis maritima (saltwort), cultivated in a recirculating raceway system at the Naguabo Aquaculture Center, Puerto Rico, across three sequential experiments: no nutrient addition, nutrient-managed mixed culture (N:P = 4:1), and nutrient-managed species-separated culture. Floating raft substrate consistently enhanced the total biomass and productivity over clay, for glasswort and sea purslane in the two experiments where the substrate could be formally tested at the tank level (effect sizes that are large to extremely large), while saltwort showed no significant substrate effect in either; a consistent raft advantage was also observed descriptively under species-separated culture, though the confounded design of that experiment did not permit formal statistical testing. Nutrient management was associated with species-specific effects: sea purslane total and edible biomass were higher under enrichment; glasswort edible fractions remained stable while the total biomass was lower, indicating allocation shifts rather than yield gains; and saltwort biomass was higher under enrichment, though this increase was not statistically significant under species-separated culture. These findings indicate that halophyte productivity was associated with the substrate configuration, nutrient context, and species-specific physiology, with floating raft systems showing a consistent biomass advantage over clay within this system and nutrient strategies warranting species-specific tailoring.