Effect of diluted seawater on yield and nutritional quality of hydroponically grown glassworts (Salicornia spp.)

Abstract

Soil and water salinization threaten agricultural productivity worldwide, stimulating interest in halophytic crops suitable for saline agriculture. Several Salicornia species (commonly known as glasswort or sea asparagus) are among the most extensively studied edible halophytes. This study investigated the effects of hydroponic cultivation with diluted seawater on biomass production and mineral composition of aerial parts in two Salicornia accessions: a wild population of S. perennans Willd. subsp. perennans (WPSP) and a peasant (farmer-selected) variety of S. europaea L.. Nutritional quality was also evaluated by quantifying selected organic compounds, nitrate, and Na in the two most common culinary forms of Salicornia: raw apical shoot portions (tips; RT) and entire shoots that were briefly blanched and subsequently stripped of their internal core (BS). Plants were cultivated for eight weeks in a floating raft system using either a standard nutrient solution (CNS, EC 2.3 dS m-1) or a saline nutrient solution prepared with diluted synthetic seawater (SNS, 12.5 g L?¹, EC 19.0 dS m-1). Saline nutrient solution markedly enhanced plant growth in WPSP, increasing fresh yield (+161%) and promoting tissue succulence, whereas these traits were not significantly affected by nutrient solution salinity in PVSE. Aerial parts of WPSP contained higher concentrations of K (+69%), Mg (+23%), and Cu (+21%) than those of PVSE. Across species, SNS significantly reduced the concentrations of total N (-31%), K (-29%), Ca (-39%), and Mn (-37%), and increased Mg concentration (+48%). Saline nutrient solution significantly reduced P concentration (-30%) only in WPSP. As expected, SNS strongly increased the Na concentration in the aerial parts, with a stronger effect observed in WPSP plants. In SNS-grown plants, Zn concentration was reduced by 42% in PVSE and by 55% in WPSP compared with CNS. No significant differences between WPSP and PVSE were detected in all biochemical traits measured in RT whereas in BS, WPSP showed lower concentrations of pigments and phenolics, and FRAP index compared with PVSE. In PVSE, no significant differences were detected between RT and BS for chlorophylls, phenolics, or antioxidant capacity, whereas in WPSP these traits were significantly lower in BS than in RT. Raw tips of CNS-treated plants showed significantly higher concentrations of dry matter (+35%), ASA (+35%), chlorophylls (+51%), and phenolics (+77%), as well as greater antioxidant capacity (+46%), compared with SNS treatment. Conversely, in BS nutrient solution did not significantly affect ASA, chlorophylls, phenolics, and antioxidant capacity. Overall, the results demonstrate strong genotype-dependent responses to salinity and post-harvest processing. Salicornia perennans shows high potential for saline hydroponic production due to its yield response, while raw shoot tips offer superior nutritional quality compared with blanched shoots, supporting their use as a fresh functional vegetable