The Stevia rebaudiana Germplasm Bank at the University of Cordoba, Colombia, plays a pivotal role in conserving and efficiently utilizing the genetic variability of this species. Despite safeguarding promising genotypes with valuable traits, such as late flowering or a significant diterpenoid glycoside content, there is a need for an efficient mass propagation protocol for elite genotypes. This study aims to develop efficient in vitro micropropagation protocols for three elite S. rebaudiana genotypes (L020, L102, and Morita II). The methods employed various combinations of cytokinins and auxins following organogenesis protocols. The results showed that optimal shoot multiplication (17.3 shoots per explant) for L020 was achieved when cultures were grown on a basal medium MS supplemented with 1 μM 6-benzylaminopurine (BAP). For L102, optimal shoot multiplication (18.5 shoots per explant) was achieved in MS supplemented with 1 μM BAP and 0.5 μM naphthalene acetic acid (NAA), while for Morita II, the best treatment was an MS supplemented with 2 μM BAP and 0.5 μM NAA, producing 16.4 shoots per explant. This study successfully achieved micropropagation for promising S. rebaudiana genotypes, highlighting the significant impact of genotype on tissue culture, particularly in shoot multiplication. Developing a successful micropropagation system is crucial for the conservation and improvement of S. rebaudiana, with significant implications for its future use and performance.

The Germplasm Bank of Stevia rebaudiana segregants of the University of Córdoba is a strategy for the use of genetic variability and efficient crop yield. There are genotypes with important characteristics such as: high tolerance to salt stress and climatic change (high CO₂ in the Earth surface), late flowering, erect architecture, and high contents of steviol glycosides. However, there is a lack of in-depth studies of morphophysiological and biochemical indicators such as gas exchange, chlorophyll a fluorescence, chloroplast pigments, and antioxidant systems, which allow us to develop early selection tools for elite genotypes. The genotypes (L020, Morita II, and L102) were found to have elite characteristics such as high efficiency in water use, excellent biomass production, and a more robust antioxidant system than the genotypes (L057 and L082). The L020 genotype presented the highest content of stevioside and rebaudioside A, followed by the Morita II genotype. We found a close correlation between the electron transport rate and the mechanisms that increase photosystem complexes. In this sense, non-photochemical cooling modulated by the release of heat by the leaves is a fact that is confirmed by the greater activity of the xanthine pool to protect the photochemical complexes in S. rebaudiana.

Due to the desire to live a healthier lifestyle, the search for nonglycosidic sweeteners has increased stevioside production in recent years. The main goal of this study was to demonstrate that S. rebaudiana grown in a CO₂-enriched environment can overcome stomatic, mesophilic and biochemical barriers that limit photosynthesis (A_N). We show that in an environment with a CO₂-enriched atmosphere (800 and 1200 µmol CO₂ mol⁻¹), the genotype 16 (G16) shows an increase of 17.5% in A_N and 36.2% in stomatal conductance in plants grown in 800 µmol CO₂ mol⁻¹ when compared to non-enriched plants. In conjunction with this issue, the plants show an efficient mechanism of dissipating excess energy captured by the photosystems. Photosystem II efficiency was increased at 1200 µmol CO₂ mol⁻¹ when compared to non-enriched plants, both in genotype 4 (25.4%) and G16 (211%). In addition, a high activity of Calvin–Benson enzymes, a high production of sugars and an enhanced production of steviosides were combined with high horticultural yield. Both genotypes (G4 and G16) showed excellent physiological indicators, with high superiority in G16. Thus, our study has demonstrated that S. rebaudiana could adapt to global climate change scenarios with higher temperatures caused by higher atmospheric CO₂.

This study was conducted to determine the effect of edaphic environmental conditions in the concentration of principal steviol glycosides and Stevia rebaudiana Bert yield, utilizing leaves from five Colombian regions. The structure of the experiment was a randomized complete block design with two treatments in a 5 × 2 factorial arrangement (5 locations × 2 radiation levels). In each experimental unit (UE), five healthy plants of similar physiological growth age were selected for the extraction of total glycosides (GT), stevioside (Stv), rebaudioside A (Rb-A),and leaf yield. Results were analyzed with the SAS statistical package (version 9.1). Concentrations of total glycosides and rebaudioside A showed a positive effect with the increase of nitrogen (N), phosphorus (P), magnesium (Mg), and copper (Cu). Therefore, they are important in the available phase of the soil to obtain an increase in these glycosides. Meanwhile, boron (B) presented a negative correlation under these conditions. For the production of stevioside, N, Mg, manganese (Mn) had a positive correlation, and calcium (Ca) and sodium (Na) had a negative correlation. Similarly, for leaf yields by locality, it was found that N, Ca, Mg, and B have a positive correlation with leaf production, while Mg, Mn, and iron (Fe) negatively correlate with biomass gain.The cultivation of stevia can be established in different soil conditions, precipitation and solar radiation in Colombia. Therefore, it is necessary to advance fertilization plans with these nutrients, considering the response of these metabolites to their application.

Cultivating Limnospira maxima, renowned for its abundant proteins and valuable pigments, faces substantial challenges rooted in the limited understanding of its optimal growth parameters, associated high costs, and constraints in the procurement of traditional nitrogen sources, particularly NaNO₃. To overcome these challenges, we conducted a comprehensive 4 × 3 factorial design study. Factors considered included white, red, blue, and yellow light spectra, along with nitrogen sources NaNO₃ and KNO₃, as well as a nitrogen-free control, for large-scale implementation. Optimal growth, measured by Optical Density, occurred with white and yellow light combined with KNO₃ as the nitrogen source. These conditions also increased dry weight and Chl-a content. Cultures with nitrogen deprivation exhibited high values for these variables, attributed to carbon accumulation in response to nitrogen scarcity. Phycocyanin, a crucial pigment for nutrition and industry, reached its highest levels in cultures exposed to white light and supplemented with KNO₃, with an impressive content of 384.11 g kg⁻¹ of dry weight. These results highlight the efficacy and cost-efficiency of using a combination of white light and KNO₃ for large-scale L. maxima cultivation. This strategy offers promising opportunities to address global food security challenges and enhance the production of industrially relevant pigments.