LED Lighting and High-Density Planting Enhance the Cost-Efficiency of Halimione Portulacoides Extraction Units for Integrated Aquaculture

Abstract

Halophytes are salt-tolerant plants that can be used to extract dissolved inorganic nutrients from saline aquaculture effluents under a production framework commonly known as Integrated Multi-Trophic Aquaculture (IMTA). Halimione portulacoides (L.) Aellen (common name: sea purslane) is an edible saltmarsh halophyte traditionally consumed by humans living near coastal wetlands and is considered a promising extractive species for IMTA. To better understand its potential for IMTA applications, the present study investigates how artificial lighting and plant density affect its productivity and capacity to extract nitrogen and phosphorous in hydroponic conditions that mimic aquaculture effluents. Plant growth was unaffected by the type of artificial lighting employed—white fluorescent lights vs. blue-white LEDs—but LED systems were more energy-efficient, with a 17% reduction in light energy costs. Considering planting density, high-density units of 220 plants m−2 produced more biomass per unit of area (54.0–56.6 g m−2 day−1) than did low-density units (110 plants m−2; 34.4–37.1 g m−2 day−1) and extracted more dissolved inorganic nitrogen and phosphorus. Overall, H. portulacoides can be easily cultivated hydroponically using nutrient-rich saline effluents, where LEDs can be employed as an alternative to fluorescent lighting and high-density planting can promote higher yields and extraction efficiencies.

Biological and Agronomic Traits of the Main Halophytes Widespread in the Mediterranean Region as Potential New Vegetable Crops

“…The halophytes most studied in hydroponics and aquaponics are the following: Salicornia dolichostachya [69], S. perennans [70,71], S. ramosissima [69,72], S. bigelovii [73], Sarcocornia neei [74,75], Halimione portulacoides [9,76,77], and Portulaca oleracea [78][79][80][81][82]. The crop yield observed in some halophytic species grown in soil-less culture is shown in Table 2, along with other information on growing conditions.…”

Special Issue on Advances in Marine Biotechnology: Exploitation of Halophyte Plants

“…The three research articles concerned halophyte cultivation, but two of them focused on halophyte culture coupled with Integrated Multi-Trophic Aquaculture (IMTA) systems. Custódio et al [37] assessed the conditions that benefit the performance of the sea purslane Halimione portulacoides in extracting dissolved inorganic nutrients from saline aquaculture effluents under IMTA systems by investigating the influence of lighting conditions and planting density on its vegetative development and nutrient (nitrogen and phosphorous) extraction capacity. The authors discovered that plant growth was unaffected by artificial lighting type, although LED systems proved more energy-efficient, and that high-density planting produced more biomass per unit of area and extracted more dissolved inorganic nitrogen and phosphorus.…”