Vegetative Growth Analysis of <em>Schoenoplectus californicus</em> (Totora): Dynamics and Physiological Mechanisms in High-Altitude Andean Lakes

This study investigates the vegetative growth of Schoenoplectus californicus (Totora) cultivated in two Andean lakes of Imbabura, Ecuador (Yahuarcocha and Imbacocha) which differ in trophic status. The aim was to evaluate how physiological and morphological factors influence growth under natural conditions. A 210-day field trial was conducted using periodic sampling and a combination of classical and functional growth analysis methods. Key growth indices—such as relative growth rate (RGR), net assimilation rate (NAR), and leaf area ratio (LAR)—were calculated from parameters like photosynthetic surface area and dry biomass. Results showed that plants from Yahuarcocha, a hypereutrophic lake, exhibited significantly higher biomass production (up to 2,380 g m⁻²) and photosynthetic area (8.68 m²) compared to those from Imbacocha. Yahuarcocha plants also reached their growth peak earlier (at 150 days) than Imbacocha plants (at 180 days). Strong correlations were found between RGR and both NAR and LAR in Yahuarcocha, while in Imbacocha, growth was primarily driven by NAR. The study concludes that both nutrient availability and anthropogenic pressures like harvesting history influence Totora’s growth dynamics. These findings support the use of physiological indicators to optimize harvesting schedules and promote sustainable cultivation strategies in highland wetland systems.