Soilless culture systems are currently one of the fastest-growing sectors in horticulture. The plant roots are confined into a specific rootzone and are exposed to environmental changes and cultivation factors. The recent scientific evidence regarding the effects of several environmental and cultivation factors on the morphology, architecture, and performance of the root system of plants grown in SCS are the objectives of this study. The effect of root restriction, nutrient solution, irrigation frequency, rootzone temperature, oxygenation, vapour pressure deficit, lighting, rootzone pH, root exudates, CO₂, and beneficiary microorganisms on the functionality and performance of the root system are discussed. Overall, the main results of this review demonstrate that researchers have carried out great efforts in innovation to optimize SCS water and nutrients supply, proper temperature, and oxygen levels at the rootzone and effective plant–beneficiary microorganisms, while contributing to plant yields. Finally, this review analyses the new trends based on emerging technologies and various tools that might be exploited in a smart agriculture approach to improve root management in soilless cropping while procuring a deeper understanding of plant root–shoot communication.

Olive oil byproducts show differences according to the olive oil extraction systems, which are called olive mill solid wastes, olive oil wastewater and olive oil wastewater sludge. Three different kinds of composts, including two-phase and three-phase olive mill solid wastes, and olive oil wastewater sludge were produced with separated dairy manure, poultry manure, and straw. The composts obtained from two-phase and three-phase olive mill solid wastes and olive oil wastewater sludge were named as two-phase, three-phase, and water sludge composts, respectively. They were separately enriched by rock phosphate and potassium salt. These composts were mixed with peat in a ratio of 0%, 25%, 50%, 75%, and 100% (v/v). Tomato seeds were sown in all mixtures on 3 February 2016. All the seeds were sown into 2 trays and each plug included 2 replicates. The trays were left in a germination room for 3 days, then moved to a heated greenhouse which is specialized for growing seedlings, and the seedlings were grown there for 3 weeks. The results showed that increasing compost ratios in the growing medium and also the enrichment of the growing medium increased organic matter content, electrical conductivity, and macro and micro nutrient concentrations. The germination period lasted longer with increasing compost ratios. The shoot length was lower at a compost ratio of over 50% excluding water sludge compost, which reacted to over 75%. The highest plant dry weights were obtained in the plants grown on the media with compost ratios of 50%, 25%, and 25% for water sludge compost, enriched two-phase compost, and enriched three-phase compost, respectively. We concluded that the composts obtained from two-phase and three-phase olive mill solid wastes and olive oil waste water sludge can be used without any need of enrichment and a ratio of 25% was found appropriate in most of the measured properties.

Salt stress is one of the main limiting factors for plant growth and crop yield. Halophytes have been postulated as a new food source since they are able to grow under saline environments and have suitable minerals and bioactive compounds. See fennel Crithmum maritimum L. is a facultative halophyte moderately tolerant to salinity. This study was carried out in order to determine the effect spraying methyl jasmonate (MeJa) on the leaves had on the growth and nutritional quality of NaCl-treated sea fennel plants grown in a hydroponic system. For that, the seedlings were treated with (a) 0.5 mM MeJa, (b) 150 mM NaCl, and (c) 0.5 mM MeJa + 150 mM NaCl. The results showed that NaCl reduced the shoot biomass of baby leaf plants, but the addition of MeJa enabled partial recovery. At the same time, when compared with the plants treated only with NaCl, MeJa favoured the Ca and K uptake and translocation to the leaves of saline-treated plants. However, MeJa did not reduce Na levels. In all treatments, nitrate and nitrite ions were in the range of the acceptable daily intake (ADI) and essential fatty acid content was elevated, although the addition of MeJa to NaCl-treated plants reduced linolenic and linoleic acid contents as compared to the plants treated only with NaCl. Total phenolic compounds were not recovered by MeJa after their decrease by salinity and no differences in antioxidant activity was found between treatments. However, all the plants maintained their antioxidant nutritional properties and increased total flavonoids after MeJa spraying to NaCl-treated plants. These results showed that MeJa spraying alleviated the negative effects of salt stress in C. maritimum grown in floating systems, improving the growth of their edible parts and increasing the total flavonoid and mineral content without affecting the total antioxidant capacity of the plant.

Climate change has continuously increased drought risk. Alternative economic, sustainable, and practical solutions are still needed to address this risk. In this study, conducted in Izmir, Türkiye, we used organic amendments, biochar, and vermicompost in combination with local tomato landraces as a strategy against drought stress. Four landraces, ‘Olympia,’ ‘Areti,’ ‘TR40430’ and ‘TR43513’ were selected from the Mediterranean Basin according to their performance to drought within the scope of the VEGADAPT Prima Project. ‘Moneymaker’ was used as a control under three irrigation treatments. Full irrigation (Ir100) was carried out to replenish the soil moisture to field capacity. For deficit irrigation, 70% (Ir70) and 40% (Ir40) of the water applied in the Ir100 irrigation was provided, respectively. Utilization of stable carbon-rich organic amendments mitigated the adverse effects of limited irrigation on plant growth, yield, water use efficiency, and soil microbial activity. Plant height and fresh and dry weight of vegetative parts were decreased, while leaf thickness and chlorophyll index were increased in the deficit irrigation. The total yield decreased by over 45% in Ir40 compared to Ir100 and Ir70. The total soluble solids, titratable acidity, fruit dry weight, and fruit firmness increased with water deficit, while fruit juice pH decreased. Irrigating at Ir70 levels with vermicompost or biochar significantly enhanced microbial activity, maintaining or improving function under the stricter Ir40 regime, though with different effects. The additive main effects and multiplicative interaction (AMMI) model was used to evaluate the overall adaptability of the studied landraces. ‘TR40430’ gave the best total yield on average, however, it showed the lowest results in terms of water use efficiency (WUE). ‘Areti’ was as good as cv. ‘Moneymaker’ in WUE. AMMI analysis also indicated the improvement of the effects of microbial activity on landraces. These results highlight the crucial role of organic amendments in enhancing soil resilience to water scarcity and supporting sustainable agricultural practices amid climate challenges.

Soil salinization due to climate change and intensive use of water and soil is increasing exponentially. Cucurbitaceae species are cultivated worldwide and the identification of salinity tolerant genotypes to be used as rootstock or scion for securing yield stability in salt affected agricultural areas is a research priority. In the present greenhouse study, we assessed the response to salinity (0 mM a non-salt control and 150 mM NaCl dissolved in the nutrient solution) in the seedlings of 30 genotypes of cucurbits grown in a floating hydroponic system. The species tested included 16 genotypes of Cucumis melo L. (CM1-16), 6 Citrullus vulgaris Schrad. (CV1-6), 2 interspecific hybrids of Cucurbita maxima Duch. × Cucurbita moschata Duch. (CMM-R1 and 2), 4 bottle gourd (Lagenaria siceraria (Molina) Standl. (LS1-4)), 1 Cucurbita moschata Duch. (CMO51-17), and 1 luffa (Luffa cylindrica Mill. (LC1)) species. Results highlighted different morphological and physiological traits between the species and genotypes and a different response to salt stress. We identified C. maxima × C.moscata interspecific hybrid CMM-R2, melon genotypes CM6, CM7, CM10, and CM16 together with watermelon genotypes CV2 and CV6 and bottle gourd LS4 as salt tolerant genotypes and possible candidates as salt resistant rootstock to be introduced in grafting programs.

Vegetable production worldwide is heavily influenced by climate change. We aimed to determine the responses of some local tomato landraces from Mediterranean countries pre-selected as drought tolerant according to previous screening tests at an early stage. Three irrigation approaches were applied: Full irrigation (Ir-Full), Deficit 1 (Ir-Def1), and Deficit 2 (Ir-Def2) irrigation. Drought stress was simulated via controlled irrigation deficit, reducing the amount of water applied by 35% and 50% in Ir-Def1 and Ir-Def2, respectively. Plant growth, yield, some fruit physicochemical properties, water consumption, and water use efficiency were measured. The results revealed that water deficit adversely affected total and marketable yields, plant growth, and biomass while enhancing some specific quality parameters. Landrace responses varied across different levels of water deficit. Among the tested tomato landraces, ‘Valldemossa’, ‘Chondrokats’, and ‘TR62367’ exhibited strong yield performance, with up to 4 kg m⁻² under water-limited conditions, whereas ‘Cherry-INRAE 1’, ‘Cherry-INRAE 3’, and ‘Cherry-INRAE 4’ excelled in fruit quality attributes, reaching up to 9.3% Brix, 14.07 mg 100 g⁻¹ vitamin C, 7.77 mg GAE 100 g⁻¹ total phenols, and 75.74 µmol TE g⁻¹ antioxidant activity. The amount of water could be reduced by 35% without compromising yield or quality in the most drought-tolerant landraces.