Hydroponic cultivation systems represent the pinnacle of soilless agriculture, enabling precise control over plant nutrition and growth conditions. The term hydroponics comes from two Greek words - 'hydro' meaning water and 'ponos' meaning labor, first used in 1929 by Dr. William Gericke, considered the father of modern hydroponics . Hydroponic cultivation systems can be categorized into two basic types: those requiring aggregates or other porous rooting media (substrate) to support the plant roots, sometimes referred to as hydroculture, and those not needing aggregates, the most widely used term being nutrient film technique (NFT) . Hydroponics uses up to 90% less water and allows for year-round production in areas where traditional soil cultivation is not possible, making it a critical solution for water-scarce regions and urban food production.

The nutrient solution is the lifeblood of hydroponic cultivation systems, requiring careful formulation and monitoring for optimal plant growth. The nutrient solution is a balanced mix of major nutrients—nitrogen, phosphorus, potassium, magnesium and sulphur—and a very low concentration of minor nutrients or trace elements including copper, boron, iron, manganese, molybdenum and zinc . The pH is crucial, with a pH of 5.8-6.2 usually aimed for, requiring a meter or test papers for monitoring . Hydroponic systems can be active, where the nutrient solution is moved around the system using a pump, or passive, where it is moved via capillary action with no pump required . Systems may also reuse the nutrient solution (recovery or recirculating systems), or the solution may not be reused (non-recovery systems) .

Common hydroponic system types include the wick system, which uses a wick to draw nutrient solution from a reservoir into the growing medium; deep water culture or floating raft, where plants are held in net pots placed in rafts that float on the nutrient solution with roots submerged and an air pump and air stone needed to keep the roots oxygenated; ebb and flow systems where plants are grown in trays that are periodically flooded with nutrient solution which then drains back into a reservoir; nutrient film technique (NFT) where plants are grown in a channel and nutrient solution continuously flows over the suspended roots; and aeroponics, which suspends roots in the air in an enclosed chamber with nutrient solution sprayed onto them . Fogponics is a new method of soilless plant production, in which plant roots are suspended in a chamber and nutrient-mixed fog is used, showing promising results in increasing crop yields and reducing water usage .

Controlled environment agriculture integrates hydroponic cultivation systems with sophisticated environmental controls to create optimal growing conditions. Greenhouse horticulture and vertical farming, also known as plant factories, are both part of Controlled Environment Agriculture (CEA) . Compared to field production, CEA allows for more control over the growth environment, often resulting in higher yields and better product quality . Light use efficiency (LUE) is a critical factor in CEA productivity, with research showing that light use efficiency for lettuce grown in a vertical farm on average was 0.55 g dry mass mol⁻¹, which was higher than 0.39 g mol⁻¹ for greenhouse-grown lettuce and substantially higher than for field-grown lettuce at 0.23 g mol⁻¹ . The maximum measured light use efficiency for lettuce grown in a vertical farm (1.63 g mol⁻¹) is close to the published maximum theoretical value, ranging from 1.26 to 1.81 g mol⁻¹ .

The future of controlled environment agriculture lies in autonomous control and digitalization of crop growth and development . Energy use efficiency has improved significantly, with Dutch greenhouse tomato production achieving about 2 kg tomatoes per m³ gas, and research demonstrating tomato production of 75 kg m⁻² using only 12 m³ natural gas and 10 kWh electricity in a greenhouse with several screens and active dehumidification . The sustainability of production in greenhouses and vertical farms is being analyzed through recent studies, with perspectives on autonomous control and digitalization shaping the future of CEA . As global population continues to grow and climate change impacts traditional agriculture, hydroponic cultivation systems and controlled environment agriculture will play an increasingly critical role in ensuring food security and sustainable production, enabling year-round cultivation of high-quality crops with minimal environmental impact.