This study evaluated the impact of different water aeration methods on lettuce growth and quality in Deep Water Culture (DWC). Three treatments were tested: diffuser stones on four times daily for five minutes, twice daily for the same duration, and no induced aeration (Kratky method). The best performance cop was observed in the system without aeration, which also had the highest polyphenol content. The correlation between high polyphenol levels and robust growth in non-aerated plants suggests these compounds play a crucial role in stress protection and optimizing metabolic processes.
In hydroponic systems, aeration is crucial for plant health and productivity as it ensures roots receive sufficient oxygen for respiration and nutrient uptake. Aeration also maintains a balanced nutrient solution by promoting beneficial microorganisms that enhance nutrient availability and absorption. The Kratky method, a passive hydroponic system, addresses aeration needs differently by relying on the natural decrease of nutrient solution levels as plants grow, creating an air gap for root oxygenation without pumps or aerators. This method offers a low-tech, cost-effective solution to aeration challenges, meeting the oxygen needs of plant roots efficiently. In this study, the Deep-Water Culture (DWC) system was used, but with an approach based on the Kratky method, i.e., without the permanent incorporation of aeration (fig. 1).
The results indicate that seedling growth was higher without the addition of air (Kratky method) than with other treatments, under the same controlled operating conditions, such as air temperature, relative humidity, and light (fig. 2).
Furthermore, this treatment achieved the highest total polyphenol levels. Elevated polyphenols in non-aerated plants suggest efficient adaptation to adverse conditions. This correlation highlights their role in stress protection and optimizing metabolic processes (fig. 3).