Aeroponics is a relatively new soilless culture technology, which may produce food in space limited cities or non-arable land with high water use efficiency. The shoot and root growth, root characteristics, mineral contents of two lettuce cultivars were measured in aeroponics, as compared with hydroponics and substrate culture. The results showed that aeroponics remarkably improved the root growth with a significant greater root biomass, root/shoot ratio, and several times higher total root length, root area and root volume. However, the greater root growth did not lead to a better shoot growth compared with hydroponics, due to the limited availability of nutrients and water. It can be concluded that aeroponics systems may be better for high value true root crops production. Further research is necessary to figure out the suitable pressure, droplet size, and misting interval in order to improve the continuously availability of nutrients and water in aeroponics, if it is used to grow crops like lettuce for harvesting above-ground parts.

Selenium (Se) is an essential element of the human diet. Therefore, it is necessary to implement Se in agricultural fertilization, although it is not considered as an essential element for plants, Se provides benefits at the level of redox metabolism, increasing the resistance of plants to various stress factors. The increase of the availability of selenium with the use of biopolymer complexes was sought in Great Lakes lettuce grown in substrate pots treated with SeO₂ (5 mg L Se), Cs-PAA + Se (5 mg L Se), and Cs-PAA. The redox metabolism was modified by increasing the enzymatic activity of glutathione peroxidase. The use of Cs-PAA + Se biopolymer complexes increase selenium up to 24 mg/Kg dry weight (DW) in plant tissues.

Water scarcity challenges have necessitated the adoption of water-saving techniques in protected and nom-protected farming. This study aimed to assess the performance of a water-saving soil-less cultivation technique and to compare it with conventional soil-based cultivation in protected farming. The soilless technique used local gravel and a mixture of peat-moss, humin-substrate, and perlite in ratios of 4:3:1.5. Three irrigation regimes were imposed using emitters 8Lh-1 design discharge (D1) emitters with 6Lh-1 design discharge (D0.75) and 4Lh-1 de-sign discharge (D0.5) for the two cultivation methods during the growth cycle of tomato by drip irrigation. The vegetative growth, fruit yield and water consumption were measured and water productivity was determined. Moreover, an economic assessment was carried out by estimating and comparing economic coefficients for the two cultivation methods. Estimated coefficients include revenues, net profit, benefit-cost ratio, break-even levels of production and prices, revenues over variable cost, and revenues on investment. The tomato fruit yield under soil-based cultivation overtopped the yield under soilless cultivation. The water productivity under the soilless cultivation was almost twice that (24.3 kg m-3) of the soil-based cultivation (15.5 kg m-3). The soilless cultivation saved 50% of irrigation water applied by the conventional soil-based method, saving energy and soil from deterioration. Revenues and net profits stimulated by higher yield coupled with lower variable cos supported the soil-based cultivation. The economic assessment showed that both cultivation methods were economically viable. However, the soil-based cultivation method was more profitable due to its higher fruit yield. Overall, the results of this study suggest that the soilless cultivation technique is a viable option for wa-ter-saving cultivation. However, the soil-based cultivation method is still more profitable due to its higher fruit yield