Agronomic potential of ethanolic extracts from the microalgae Limnospira platensis and Porphyridium cruentum on common bean (Phaseolus vulgaris) crops

Abstract In recent years algae extracts have gained recognition in global agriculture for their capacity to enhance the growth and yield of leguminous plants like the common bean ( Phaseolus vulgaris ), which is vital in many countries and plays a key role in ensuring global food security. This study evaluated the biostimulant and biopesticide potential of ethanolic extracts from Limnospira platensis and Porphyridium cruentum on common bean, using seed priming and soil application methods. Extracts were tested at 0.1, 0.5, and 1.0 mg mL –1 . Seed treatment with L. platensis at 0.1 mg mL –1 increased shoot length by 59% and total seedling length by 32%. At 1.0 mg mL –1 , shoot dry weight rose by 21%, and total dry weight by 20%. In soil application, L. platensis extract at 1.0 mg mL –1 increased root fresh weight by 28.8% and shoot dry weight by 25.9%. Porphyridium cruentum extract promoted seedling elongation (up to 42%) and fresh biomass accumulation (17.6%) at 1.0 mg mL –1 . Photosynthetic pigment levels were enhanced in L. platensis treatment, with chlorophyll a and carotenoids increasing by 17% and 31%, respectively. The chemical characterization revealed the presence of key bioactive compounds, such as peptides, sphingolipids, fatty acids, and phospholipids, commonly associated with plant growth promotion and physiological responses. The extracts enhanced growth, biomass accumulation, and pigment levels, suggesting their potential as eco-friendly agricultural inputs. Further research is needed to explore their application in other crops.