Summary
This paper examines the impact of an extract derived from the green macroalga Cladophora glomerata, using an innovative method known as ultrasound-assisted extraction (UAE), on the germination and early growth of three narrow-leaved lupin varieties: Homer, Jowisz, and Tytan. This research study was conducted on seeds harvested from five growing seasons (2015-2019) during their successive propagation stage. Overall, 45 experimental groups were tested. Narrow-leaved lupin, like other legumes, offers various beneficial effects on soil structure and fertility, making it a valuable fodder crop due to its high nutritional value. The algae extract was administered in two concentrations: 10% and 20%, and its biostimulant effect was evaluated based on the germination percentage, root, hypocotyl, epicotyl length, and chlorophyll content in cotyledons. The results revealed that the 20% extract significantly enhanced the growth of seedlings across all lupin cultivars compared to the 10% application. The Jowisz variety exhibited the most substantial improvement in root length among the three cultivars tested.
The authors further discuss the concept of ultrasounds, which refer to sound waves with frequencies higher than 16 kHz. These sound waves are increasingly being utilized in various industries, including agriculture, as an environmentally friendly and non-toxic means of physically stimulating seeds. This stimulation can promote germination, seedling growth, and the production of beneficial active compounds. Seed pre-treatment involves placing the seeds in a device that generates ultrasound (typically an ultrasonic bath) and selecting appropriate parameters, such as power, frequency, time, and temperature, to influence the physiological activity of seeds.
Acoustically induced cavitation, which involves the formation, growth, and subsequent collapse of bubbles generated by the introduction of ultrasonic waves into liquid, has a positive effect on seeds. The authors introduce a novel approach in agriculture that utilizes ultrasounds to prepare plant or macroalgae extracts through a process known as Ultrasound-Assisted Extraction (UAE). These extracts can act as biostimulants for seed germination and plant growth and development. This method is commonly employed in the extraction of bioactive compounds from biomass for applications in cosmetology, pharmacology, or medicine, but has not yet been widely adopted in agriculture.
Ultrasound-assisted extraction (UAE) stands out as a modern method of isolating active compounds, gradually replacing conventional, time-consuming techniques that rely on organic solvents. In UAE, pressure changes as sound waves propagate through a medium. Acoustic cavitation, which involves the expansion and collapse of bubbles, converts sound waves into mechanical energy, causing cells and their walls to rupture. This process leads to reduced particle size and increased contact between the solvent and isolated compounds. Additionally, the UAE allows for the extraction of compounds sensitive to high temperatures without compromising their integrity.
It also increases extraction yields and can be scaled up for industrial applications. Moreover, the UAE facilitates the production of extracts at a lower cost due to the relatively low power consumption of ultrasound devices. These devices are also more affordable and user-friendly compared to other modern extraction techniques, such as supercritical fluid extraction (SFE) and high-pressure-assisted extraction. The authors provide evidence from their research that numerous plant extracts prepared using UAE demonstrate nutritional benefits and positively impact the growth and development of seedlings, as observed in studies on white cabbage under laboratory and field conditions. These findings highlight the potential of the UAE to enhance plant growth and development.
In conclusion, this study demonstrates that the extract obtained using ultrasound-assisted extraction (UAE) from the green macroalga Cladophora glomerata can significantly enhance the germination and early growth of narrow-leaved lupin varieties. The 20% extract proved to be more effective than the 10% application across all lupin cultivars tested. The authors also discuss the benefits of using UAE in agriculture and provide evidence from their research on the positive impact of UAE-prepared plant extracts on seedling growth and development.
