Yield, quality and resource use efficiency of basil grown in alternative soilless growing systems

Soilless production systems are popular for the benefits of increased yield and quality, reduced potential for pollution into the environment and efficient use of resources. Soilless culture may be classified in two main categories: i) growing media-based systems, which include different alternative growing media (organic or synthetic), containers (pots, slabs, etc.) and solution delivery method (drip, sub-irrigation), and ii) water culture or hydroponic systems, in which plants are directly grown in a nutrient solution in absence of a growing medium. These systems could be further classified in a) static growing systems, in which the nutrient solution is static and is held in a container, and b) non-static growing systems, in which the nutrient solution is circulating. The effects of the different types of soilless growing systems on crop yield, quality, and resource use efficiency, have not been well researched. A study was conducted under protected environment, to compare side-by-side in the same environment and assess the effect of four different soilless production systems including deep water culture (DWC), Kratky, nutrient film technique (NFT), and sub-irrigation on yield, nutritional quality, and resource use efficiency of ‘Italian Genovese’ and ‘Dark Opal’ basil. The same nutrient solution was used across systems. The highest yielding system was the floating or DWC system, recording 21% higher yields than the second highest yielding system, NFT. The most efficient use of nutrient solution was observed with the Kratky (also known as “air-gap”) and DWC system recording 41% less nutrient solution use than the second most nutrient solution efficient systems, NFT and sub-irrigation. Nutritional quality, measured in terms of total phenolic compounds and total antioxidant activity, did not vary very much between the hydroponic systems. This study highlights how alternative soilless systems can provide different benefits in terms of yield, quality, and resource use efficiency.