Vertical tower aeroponics for lettuce: A study on growth and water usage

Introduction

Aeroponics, a soilless cultivation method, allows plant roots to be suspended in air and periodically misted with a nutrient-rich solution. This technique, developed by NASA, is now gaining traction in urban and sustainable agriculture. Lettuce, a popular leafy vegetable with high market demand, benefits from the precision and efficiency of aeroponic systems. Many leafy vegetables and fruits can be cultivated in the aeroponic system (Gopinath et al., 2017) [2] . Plant grown in the aeroponic system also been shown to uptake more minerals and vitamin, making the plants healthier and potentially more nutritious (Kumari and Kumar 2019) [3] . These systems use up to 90% less water than even the most efficient hydroponic systems, making them the most water-efficient method for vertical farming (Vashishta et al., 2024) [5] . Aeroponics is well-suited for growing a variety of vegetables, including lettuce (Lactuca sativa), prefers a water pH of 5.6-6.5. Optimal humidity for lettuce growth is between 65% to 78%, with an ideal temperature range of 25° to 28 °C (Awalina et al. 2022) [1] . In the future, it would be a difficult task to provide a fresh and clean food supply for the fast-growing population using traditional agriculture. (Lakhiar et al. 2018) [4]

Materials and Methods

The study was conducted in a Laboratory at CAET, DBSKKV, Dapoli. A 1.8 m tall vertical aeroponic tower made of food-grade PVC was constructed to support 36 lettuce plants. Essential system components included a nutrient tank, submersible pump, grow lights, and monitoring instruments (pH meter, EC meter, thermometer, lux meter). Lettuce seeds (Iceberg, Concord, Maximus) were germinated in cocopeat trays and transplanted at 16 days after sowing. Nutrient solutions were prepared with macro-and micro-elements in A and B stock solutions (Table 2), added at 2 ml/L each. This system includes pipes with small holes through which nutrient-rich water flows continuously. As the water moves through the pipes, it comes into contact with the hanging roots, ensuring they stay moist and absorb all the nutrients needed for growth. As the roots are suspended in the air, they get excellent access to oxygen, which is very important for healthy root development and overall plant growth. This combination of water and air around the roots creates the ideal environment for faster and more efficient plant growth. The important crop parameters such as plant height, root length, and the number of leaves were measured to study the growth of lettuce.

Results and Discussion

Environmental conditions were maintained within optimal ranges In the experiment, a grow light was used, which gave a fixed light intensity of 5090 Lux. The temperature and humidity readings are shown in Table 3.

Chemical Properties of nutrient solution

The recorded value of EC, pH and TDS of nutrient solution used in the experiment are shown in Table 4. These observations were taken from 04/05/2025 to 15/05/2025. The EC, pH and TDS were found in range of 1.1 to 1.6 mS/cm, 5.6 to 6.3 and 558 to 780 ppm. These values helped ensure the plants were receiving the correct amount of nutrients and water quality for healthy development. Regular monitoring provided a suitable environment for proper growth in the aeroponic system

Crop Parameters

The readings related to crop parameters such as Root length plant height, and Number of leaves is shown in Table 5. These values help us understand how the crop responded to different conditions like water use and solution treatment. The maximum of plant height, root length, numbers of leaves are found to be 19.3 cm, 10.0 cm and 18 leaves, respectively. The lettuce growth of is shown in Fig. 1 and2.

Water used efficiency

In the experiment 61 liter of water was used. Along with that 178 ml of solution A and 165 ml of solution B were added. The readings obtained from experiment is given in the Table 6. 12.5 The total lettuce crop yield was found to be 1.900 kg (1900gm) in this setup. Thus, by using formula the water used efficiency was found to be 31.15gm /lit.

Conclusion

The vertical tower aeroponic system offers an efficient, spacesaving, and sustainable method for growing lettuce, particularly suitable for urban and water-scarce areas. The study confirms the viability of this method for enhanced crop yield and resource management.

References

1. Awalina R, Erona M, Rusnam. Lettuce (Lactuca sativa L) growth in aeroponic systems with differences in nutritional time. IOP Conf Ser Earth Environ Sci. 2022;1059(1):012014. https://doi.org/10.1088/17551315/1059/1/012014
2. Gopinath G, Ramesh M, Vignesh T. Aeroponics: A novel farming technique. Int J Agric Sci Res. 2017;7(2):135-40.
3. Kumari R, Kumar R. Aeroponics: A review on modern agriculture technology. Indian Farmer. 2019;6(4):286-92. https://www.researchgate.net/publication/342804239
4. Ali LI, Jianmin G, Naz ST, Ali CF, Noman BA. Modern plant cultivation technologies in agriculture under controlled environment: a review on aeroponics. J Plant Interact. 2018;13(1):338-52.
5. Vashishta A, Singh G. Vertical farming: An agricultural revolution. Int J Sci Res Eng Trends. 2024;10(5):1934-42.