Supplementation of carbon dioxide ameliorated the physicochemical attributes of duckweed (Lemna trisulca)

Abstract

Duckweed has gained attention as a potential aquatic crop for starch and protein production. Compared to most duckweed species, Lemna trisulca (L. trisulca) is distinguished by its submerged habitat. In context of rising CO₂ levels, which pose significant enviromental risks, duckweed presents potential as an effective carbon sequestration agent. Despite its relevance, research on L. trisulca for carbon sequestration remains limited, particularly when compared to microalgae. This study inestigates the effects of varying carbon dioxide (CO₂) concentrations (400 ppm,10,000 ppm and 50,000 ppm) on the relative growth rate, biomass accumulation and enzyme activity of L. trisulca. The results indicated that CO₂ supplementation significantly enhanced biomass production, photosynthetic pigment concentration, activity of photosynthetic enzymes, and starch/protein accumulation. Compared to ambient CO₂ concentration, under the 50,000 ppm CO₂ treatment, fresh weight, starch content and protein levels increased by 11.6 times, 3.3 times and 1.6 times, respectively. Furthermore, the carbon sequestration capacity in high concentration (HC) treatment group was 18.1 times higher than control concentration (CC) treatment groups and 3.4 times of that in media concentration (MC). This is the first study to explore the physiological response of L. trisulca to elevated CO₂ concentrations. The specie demonstrated higher growth efficiency and carbon sequestration ability when exposed to high CO₂ conditions. The findings provide critical insights into the potential application of L.trisulca in the process of carbon sequestration, and lay a foundation for the utilization of L.trisulca in sustainable bioenergy production.