Cultivating the Mediterranean Wild Edible Species Cichorium spinosum L. in Aquaponics: Functional and Growth Responses to Minimal Nutrient Supplementation

Aquaponics is a plant and fish co-cultivation system with high sustainability, yet sub-optimal concentrations of Fe and K often compromise crop yields. We cultivated the Mediterranean wild edible Cichorium spinosum L. (Greek name: stamnagathi) in an aquaponics setup following a minimal supplementation approach that focused on Fe and K. Stamnagathi and tilapia fish were co-cultivated under (i) solely Fe, (ii) Fe+K input and (iii) no-input Control treatments. We aimed to evaluate the feasibility of aquaponics for stamnagathi cultivation, identify the system's bottlenecks, and propose optimization measures. Several plant's growth and functional parameters were monitored throughout the 35-day experimental period, notably instantaneous gas exchange and photosynthetic capacity via light response curves, state and efficiency of the photosynthetic machinery, pigment content, and yield and morphometric assessments. Fish growth characteristics and survival rates remained unaffected. Fe deficiency was crucial in shaping the responses of Control stamnagathi, which showed inferior performance in terms of photochemistry, chlorophylls content, light use efficiency and, subsequently, photosynthetic activity. Fe and Fe+K-treated plants exhibited similarly high performance in all studied parameters and achieved 4.5- and 4-fold increased yields, respectively, compared to Control. The results demonstrate that aquaponics is an advantageous cropping system for stamnagathi and solely Fe supplementation is adequate to promote excellent performance and yield of this oligotrophic species.

Automated summary

Aquaponics is a sustainable plant and fish co-cultivation system. However, sub-optimal concentrations of Fe and K often reduce crop yields. In this study, stamnagathi plants were cultivated in an aquaponics setup with minimal supplementation of Fe and K. The results showed that Fe supplementation alone or in combination with K significantly improved plant growth and yield compared to the control group.