Comparative analysis of Moringa oleifera leaf extracts obtained using different extraction techniques and their influence on Cowpea seed germination

• Influence of Moringa oleifera leaf extracts on cowpea seed germination. • Compared various extraction techniques, including Pressurised Hot Water Extraction, and assessed their efficiency. • The potential of green extraction techniques in enhancing plant biostimulant properties. • Explored the differences in germination rate due to bioactive compounds in the extracts. Moringa oleifera leaf extract (MLE) has garnered significant attention as a natural plant growth stimulant, offering a cost-effective alternative to synthetic fertilisers due to its rich content of cytokinins, antioxidants, and essential macro- and micronutrients. Pressurised Hot Water Extraction (PHWE) has emerged as an environmentally friendly, rapid, and efficient technique for extracting these bioactive compounds from plant biomass. In this study, seven different MLEs were evaluated for their effects on cowpea ( Vigna unguiculata ) seed germination, using tap water as the control. These included MLEs obtained at 25, 50, 100, and 150 °C using PHWE, as well as extracts from a stirred batch system, a blended method, and a commercial biostimulant. Seeds treated with the control, 25 °C, and 150 °C extracts achieved 100 % germination, while the commercial biostimulant resulted in only 30 %. The 25 °C extract produced the longest hypocotyls (13.2 cm), whereas the commercial biostimulant yielded the shortest (2.1 cm). Secondary root emergence was highest (100 %) in seeds treated with the control, 25 °C, and stirred batch extracts. The 50 °C extract showed the greatest emergence of rudimentary leaves (43 %). Overall, the commercial biostimulant underperformed across all measured parameters. This study highlights the distinct influence of different extraction methods on the bioactivity of MLEs, underscoring their potential as sustainable growth-promoting agents in agriculture.