Biostimulation of Plectranthus amboinicus (Lour.) Spreng. with Different Yeast Strains: Morphological Performance, Productivity, Phenotypic Plasticity, and Antioxidant Activity

Abstract

Due to the growing knowledge about the microorganism–plant relationship, medicinal plants have gained great attention in their bio fertilization programs using biostimulants based on microorganisms. Plectranthus amboinicus (Lour.) Spreng. is a perennial herb belonging to the family Lamiaceae and has therapeutic and nutritional properties attributed to its natural phytochemical compounds, which are highly valued in the pharmaceutical industry. A pot experiment was conducted to evaluate the efficiency of Rhodotorula muciligenese (Y1), Candida sake (Y2), Candida apicola (Y3), and Candida kunwiensis (Y4) yeast strains in concentrations of 0 (C1), 1 × 104 (C2), 1 × 107 (C3), and 1 × 109 (C4) CFU mL−1 on the growth performance, productivity, and antioxidant activity of P. amboinicus plants. Yeast applications promoted growth attributes, nutritional value, and antioxidant activity in P. amboinicus leaves. Candida apicola exhibited the greatest root growth, herb weight, and essential oil production; it also stimulated carbohydrates, protein, and mineral content, as well as DPPH and FRAP activities. Whereas Rhodotorula muciligenese recorded the lowest values in this respect, among the concentrations used, the 1 × 107 CFU mL−1 concentration showed the highest values in this respect. These new findings showed that the foliar application of Candida apicola not only maximized the growth and productivity but also maximized the nutritional value and antioxidant activity of P. amboinicus.

Foliar Spray or Soil Drench: Microalgae Application Impacts on Soil Microbiology, Morpho-Physiological and Biochemical Responses, Oil and Fatty Acid Profiles of Chia Plants under Alkaline Stress

“…Total protein was assessed using the semi-micro Kjeldahl technique [ 39 ]. Total carbohydrates were measured colorimetrically as previously described by Alshallash et al [ 40 ] using the phenol–sulfuric acid technique [ 41 ]. For extracting total phenolics and DPPH in the seeds, 1 g of seed samples was mixed with 10 mL of ethanol (60%) and left for 3 h under shaking conditions at room temperature; then, the mixture was centrifuged at 3000× g for 15 min.…”

Integrated Action of Rhizobacteria with Aloe vera and Moringa Leaf Extracts Improves Defense Mechanisms in Hibiscus sabdariffa L. Cultivated in Saline Soil

“…All N-fixing bacteria strains used in this study showed significant enhancements in roselle growth and yield under saline conditions. These improvements may be due to the phytohormones produced by N-fixers, including IAA [42], which enhances division, elongation, and differentiation of plant cells [43,44]; tryptophol; and indole butyric acid (IBA), which stimulate plant growth indirectly [45,46]. NFB can increase plant growth by elevating the fixation of atmospheric nitrogen, mineral solubilization, and siderophore production.…”

Net Photosynthesis and Biomass Production in Stevia, Eggplant, and Cowpea Can Be Improved by Fertilization with Cyanobacteria (Limnospira maxima)

“…A study with Plectranthus amboinicus showed a lower plasticity index for the leaf number (0.23 and 0.28) and oil percent (0.24 and 0.25). The branch number, essential oil yield, and herb and RDW traits showed great enhancements that were affected by yeast applications, and they gave the highest results [68].…”