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Seaweed extract (SE) application is a contemporary and sustainable agricultural practice used to improve yield and quality of vegetable crops. Plant biofortification with trace element is recognized as a major tool to prevent mineral malnourishment in humans. Mo deficiency causes numerous dysfunctions, mostly connected to central nervous system and esophageal cancer. The current research was accomplished to appraise the combined effect of Ecklonia maxima brown seaweed extract (SE) and Mo dose (0, 0.5, 2, 4 or 8 µmol L−1) on yield, biometric traits, minerals, nutritional and functional parameters, as well as nitrogen indices of spinach plants grown in a protected environment (tunnel). Head fresh weight (FW), ascorbic acid, polyphenols, N, P, K, Mg and nitrogen use efficiency (NUE) were positively associated with SE treatment. Moreover, head FW, head height (H), stem diameter (SD), ascorbic acid, polyphenols, carotenoids as well as NUE indices were enhanced by Mo-biofortification. A noticeable improvement in number of leaves (N. leaves), head dry matter (DM) and Mo concentration in leaf tissues was observed when SE application was combined with a Mo dosage of 4 or 8 µmol L−1. Overall, our study highlighted that E. maxima SE treatment and Mo supply can improve both spinach production and quality via the key enzyme activity involved in the phytochemical homeostasis of SE and the plant nutritional status modification resulting in an enhanced spinach Mo tolerance.

Light and nitrogen strongly affect the growth, yield, and quality of food crops, with greater importance in green leafy vegetables for their tendency to accumulate nitrate in leaves. The purpose of this research was to explore the effect of two greenhouse films (Film A and B) on yield, and quality of spinach grown under different nitrogen regimes (not fertilized—N0%, sub-optimal N dose—N50%, optimal N dose—N100%). Film A and Film B were used as clear and diffused light films, with 75% and 87% thermicity, and 85% and 90% total transmittivity, respectively, where only Film B had a UV-B window. Film B elicited an increase in yield (22%) and soil–plant analysis development (SPAD) index (4.6%) compared to the clear film, but did not affect chlorophyll a, b, and total chlorophyll content. In addition, the diffuse film significantly decreased ascorbic acid in the crop but had no effect on lipophilic antioxidant activity and phenols content, but decreased ascorbic acid content. Finally, nitrate content was strongly increased both by nitrogen dose (about 50-fold more than N0%) and greenhouse films (about six-fold higher under diffuse light film), but within the legal limit fixed by European Commission. Therefore, irrespective of N levels, the use of diffuse-light film in winter boosts spinach yield without depressing quality.

Selenium (Se) is an essential trace element for humans due to its importance in a number of enzymes. Vegetable grafting is a valuable tool to overcome biotic and/or abiotic issues and to increase vigour, yield traits and fruit quality. The present work aimed at testing both different Se concentrations (0.0, 1.0, 2.0 and 4.0 μmol Se L−1) supplied via fertigation and grafting on cherry tomato in soilless culture. Se at 2.0 μmol L−1 improved total fruit yield by 60.0 % and 31.4 % in ungrafted and grafted plants, respectively as compared to the control. Marketable yield was positively affected by Se-biofortification and grafting. Se at 2.0 μmol L−1 improved N use efficiency by 60.3 % and 31.5 % in ungrafted and grafted plants, respectively. Furthermore, Se at 4.0 μmol L−1 and grafting enhanced fruit firmness, SSC, polyphenol content and total carotenoids. Ascorbic acid and lycopene were enhanced by Se-doses and grafting. Fruit Se concentration in ungrafted plants varied from 0.1 mg kg−1 of dry weight (DW) in the control to 8.9 mg kg−1 DW in plants treated with 4.0 μmol Se L−1. Se fruits concentration in grafted plants ranged from 0.08 in the control to 9.8 mg kg−1 DW in plants treated at 4.0 μmol L−1. Non-grafted and grafted plants manifested an increment in the hazard quotient (HQgv) in reaction to Se. HQgv fluctuated from 0.002 to 0.353, with a daily intake for Se below the recommended value. Finally, Se-biofortification (at 2.0 or 4.0 μmol L−1) and grafting succeeded in improving tomato plant performance, nutritional and health-promoting compounds.

The herbaceous grafting of fruiting vegetables is considered a toolbox for safeguarding yield stability under various distresses and for improving fruit quality. Inoculation with arbuscular mycorrhiza (AM) fungi seems also to be an efficient tool for increasing the assimilation, uptake and translocation of macroelements and microelements, for modulating plant secondary metabolism and for overcoming several forms of plant distress. The present work evaluated the combined effect of grafting the &ldquo, Birgah&rdquo, (B) eggplant onto its wild/allied relatives&rsquo, rootstocks (Solanum torvum (T), S. macrocarpon (M) and S. paniculatum (P)) and AM fungi (R. irregularis) on the yield, fruit quality, nitrogen use efficiency, mineral profile, and nutritional and functional quality. The B/T, B/M and B/P grafting combinations significantly increased the marketable fruit and fruit number compared with those in the ungrafted control. Furthermore, irrespective of the grafting combinations, AM fungi significantly enhanced the marketable fruit, fruit number and nitrogen use efficiency (NUE) by 13.3%, 12.7% and 13.3%, respectively compared to those in the untreated control. Exposing the B/T and B/P grafted plants to the +AM treatment significantly increased the ascorbic acid contents by 17.2% and 10.4%, respectively, compared with those in the ungrafted control. Fruits from the combination B/P &times, +AM had a higher chlorogenic acid content than fruits from the ungrafted control plots. Finally, the B/T &times, +AM and B/P &times, +AM combinations decreased glycoalkaloids by 58.7% and 63.7%, respectively, compared with those in the ungrafted control, which represents a highly important target for eggplant fruit healthiness.

The current research elucidated the agronomical, physiological, qualitative characteristics and mineral composition of lettuce (Lactuca sativa L. var. longifolia) after treatments with a beneficial fungus Trichoderma virens (TG41) alone or in combination with a vegetal biopolymer-based biostimulant (VBP, &lsquo, Quik-link&rsquo, ). The experiment consisted of lettuce plants grown in three N conditions: sub-optimal (0N kg ha&minus, 1), optimal (70N kg ha&minus, 1), and supra-optimal (140N kg ha&minus, 1) N levels. Lettuce grown under 0N fertilization showed a significant increase in fresh yield when inoculated with TG41 alone (45%) and a greater increase with TG41 + VBP biostimulant (67%). At 48 days after transplanting, both the TG41 alone or TG41+VBP biostimulant induced higher values of CO2 assimilation in comparison to the control. The mineral concentrations in leaf tissues were greater by 10% for K and 12% for Mg with the TG41+VBP treatments compared to the untreated lettuce. The lettuce plants receiving either TG41 alone or TG41+VBP biostimulants had a significantly lower nitrate content than any of the untreated controls. In non-fertilized conditions, plants treated with TG41+VBP biostimulants produced lettuce of higher premium quality as indicated by the higher antioxidant activity, total ascorbic acid (+61%&ndash, 91%), total phenols (+14%) and lower nitrate content when compared to the untreated lettuce.

Nitrate is the principal source of nitrogen for most higher plants. Particularly leafy vegetables require large quantities of nitrate fertilizer to attain maximal yields. The crop yield and quality as well as nitrate accumulation in leafy vegetables depends upon many preharvest factors such as genetic materials, agronomical and environmental factors. Three greenhouse experiments were carried out in order to assess the effects of preharvest factors (cultivars, plant density and N dose) on yield and quality of spinach (Spinacia oleracea L.). In the first trial four spinach cultivars were compared in terms of yield and quality attributes. The marketable yield of the four cultivars tested was in the following order: ‘Tasman’ = ‘Kookaburra’ > ‘Platypus’ = ‘Regiment’. No significant differences among cultivars were observed for the βcarotene, vitamin C and nitrate contents. In the second trial, treatments were defined by four plant densities (800,000; 1,000,000; 1,200,000; 1,500,000 seeds ha-1). The lowest marketable yield was observed under the lowest plant density, whereas no significant difference was recorded between the other treatments. The highest leaf dry matter, K, and nitrate contents were recorded at 1000000 seeds ha-1. In the third experiment we evaluated the effects of four N fertilizer doses (0, 75, 150 and 225 kg ha-1) on crop performance. Marketable yield increased quadratically with increasing N application with the highest values recorded at both 150 and 225 kg ha-1 indicating a luxury consumption of the nutrient at 225 kg ha-1. Finally, the highest protein and nitrate contents were observed at 225 kg ha-1 of N.

Microgreens appeared in the human diet as a decoration of culinary dishes, due to their shape, tenderness and vivid colours. They are currently attracting researchers' attention for their nutraceutical properties. In fact, they were found to be packed with vitamin C, carotenoids and minerals. The genetic aspect is one the most important preharvest factors. Microgreens of the Brassicaceae family are well researched. In our study, six genotypes belonging to the Brassicaceae family: Cress (Lepidium sativum L., 'Curled'), komatsuna (Brassica rapa L. var. perviridis 'Comred F1'), mibuna (Brassica rapa L. subsp. nipposinica 'Japanese greens'), mizuna (Brassica rapa var. japonica 'Greens'), pak choi (Brassica rapa L. subsp. chinensis 'Red Wizard F1'), tastoi (Brassica rapa L. subsp. narinosa), were cultivated in a growth chamber, and analysed to determine colourimetric parameters, nitrate content, minerals, bioactive molecules (chlorophylls, carotenoids, ascorbic acid, total phenols) and antioxidant activity. The results confirmed the hypothesis of genetic variability for the analysed parameters. pak choi and komatsuna had the highest content of macronutrients (P, S, K and Ca). Pak choi had the highest total chlorophylls and total ascorbic acid content. These findings place emphasis on an appealing product like microgreens.

The preservation of local landraces represents a crucial point in biodiversity maintenance and it necessarily starts from a qualitative and morphological characterization. The 'San Marzano' tomato (Solanum lycopersicum L.) is an elongated fruit cultivar particularly suitable for processing and represents one of the most significant horticultural products for the Italian food industry. Five 'San Marzano' landraces ('SM Bellizzi 1', 'SM Bellizzi 2', 'SM Bellizzi 3', 'SM Montoro Inferiore' and 'SM Sarno') characterized by different fruit shapes (pointed, round and hollow) were compared in terms of yield, nutritional and functional quality. The fruit dry matter percentage as well as the juice EC ranged from 4.94 to 7.10% and from 3.04 to 3.80 dS m-1, respectively, with the lowest values observed in 'SM Montoro Inferiore'. The highest total soluble solids content was recorded in both 'SM Montoro Inferiore' and 'SM Sarbo', followed by 'SM Bellizzi 1' and 'SM Bellizzi 3', whereas the lowest values were observed in both 'SM Bellizzi 2' and 'SM Bellizzi 3'. Among the three macronutrients analyzed K was the most abundant macro-mineral, followed by phosphorus and finally nitrate. 'SM Bellizzi 1' was richer in P and K compared to the rest of the landraces tested. The highest levels of hydrophilic and lipophilic antioxidant activities were recorded in 'SM Sarno' and 'SM Bellizzi 3', respectively. Our findings will contribute toward the documentation of nutritional and functional quality profiles of an important collection of niche products such as the SM tomato.

Sweet basil (Ocimum basilicum L.) is one of the most common aromatic herbs cultivated all over the world. It is widely used for its aromatic and culinary purposes. Consumer demand for fresh sweet basil has been on the rise and many farmers of leafy vegetables and aromatic herbs have oriented their production schemes to include basil. The genetic material is a key preharvest factor and the major determinant of variation in yield and quality of leafy vegetables. Another important preharvest factor that may modulate yield and nutritional quality of sweet basil could be the growing medium. The aim of this research was to assess in a multi-factorial approach the effects of two sweet basil cultivars (Napoletano and Genovese) and two substrates (rockwool and an innovative inert substrate, SISAL fiber) on plant growth, marketable yield, nitrogen content and nutritional quality. The plant growth parameters, yield and especially the bioactive compounds were mostly affected by the growing media and to a lesser extent by the genetic material. When averaged over growing media, the highest leaf number was observed in 'Genovese' while an opposite trend was recorded for the leaf area. Irrespective of the sweet basil cultivar, plants grown on rockwool exhibited a higher leaf area, leaf fresh weight and dry biomass compared to those grown on SISAL fiber substrate. Contrarily to crop productivity, sweet basil grown on SISAL was characterized by high levels of lipophilic antioxidant activity, total chlorophyll and carotenoids, whereas no significant effect among treatments were recorded on total phenols. Although the yield reduction with SISAL was quite significant, the basil plants grown on this innovative substrate produced leaves with high concentrations of bioactive compounds. Additional researches should focus on elucidating the Genotype × Substrate interaction in order to select the best combinations.

Seed priming is the induction of a particular physiological state in plants by the treatment of natural and synthetic compounds to the seeds before germination, with the aim to boost germination percentage and seedlings performance. The aim of the current research was to assess the influence of three seed priming treatments (control, cold priming and osmo priming) on the total germination percentage and the transplant quality of six vegetable species (artichoke [Cynara scolymus L.], endive [Cichorium endivia L.], fennel [Foeniculum vulgare L.], onion [Allium cepa L.], pepper [Capsicum annuum L.] and tomato [Solanum lycopersicum L.]). The transplants performance was compared in terms of biometric measurements and pigments (chlorophyll and carotenoids). Our results demonstrated that the positive effect of seed priming on total germination was species-dependent. Cold priming makes Cynara scolymus L. seeds reach 65% germination, Cichorium endivia L. seeds 93%, and Allium cepa L. seeds 81%. The osmo priming treatment brings the germination of Capsicum annuum L. seeds to 87%, and the Solanum lycopersicum L. seeds to 83%. Foeniculum vulgare seeds show the highest germination capacity compared to other tested species. Even the morphological traits of the six vegetable transplants were also influenced by the two priming methods in a specific-species manner. Osmo priming increased the total phenols content in Cichorium endivia L. and Solanum lycopersicum L. Finally, In Allium cepa L. both priming treatments reduced chlorophyll b and total chlorophyll content.

Plant biostimulants are substances (i.e., humic and fulvic acids, protein hydrolysates and seaweed extracts) and microbial inoculants (i.e., mycorrhizal fungi and plant growth promoting rhizobacteria-PGPR) that have been introduced as an efficient, safe and sustainable tool to optimize root system thus boosting crop performance, and nutrient use efficiency as well as enhancing tolerance to environmental stressors in vegetable crop production. The stimulation of biomass production in response to biostimulant application has been often associated to the action of specific signaling molecules on plant metabolism and physiology. Several trials have shown that Cucurbit crops can also benefit from the application of biostimulants. Early application at transplanting or in nursery of arbuscular mycorrhizal fungi (Rhizoglomus irregulare and Funneliformis mosseae) or vegetal biopolymer-based biostimulant on several Cucurbit crops (e.g., cucumber, melon, zucchini) were able to boost root growth and to activate defense mechanisms against environmental stresses (e.g., salinity, soil acidty and alkalinity). Moreover, foliar applications of biostimulant substances during the growing cycle were also effective in promoting crop productivity and increasing nutritional and functional quality in Cucurbit crops. Several examples will be presented and discussed together with possible mechanisms involved.

The goal of sustainable production is to reduce environmental degradation, to maintain agricultural productivity, to promote economic viability, as well as to reduce energy losses. Bedding plant sector is an important part of the nursery industry. Improving cultivation practices that increase the performance of potted ornamentals may become a promising and effectively sustainable strategy to be adopted in ornamental nursery. Among the important group of plant biostimulants soil activator complexes obtained by combination of macroalgae, zeolites, humic acids and soil bacteria improves the chemical-physical and microbiological properties of the substrate. The aim of this study was to assess the effect of a granular soil activator (Agrosil® Turf Algin) alone or in combination with two commercial controlled-release fertilizers (CRF) on growth, ornamental quality, leaf gas exchanges as well as mineral composition of two bedding plants: Begonia semperflorens and Salvia splendens. The plant growth parameters and the ornamental quality recorded in Agrosil-treated bedding plants were species-dependent, and were also affected by CRF type. Our results also demonstrated that the activator application enhanced several growth performance and quality parameters of the two selected bedding plants: plant height, canopy volume, leaf area and colorimetry, number of flowers in both species. The increased crop performance recorded in both species in the treatment B+A could be attributed to an increase in photosynthetic activity as well as to a better nutritional status (higher N, P, and K).

Interest in plant biostimulants is on the rise, compelled by the growing interest of greenhouse growers and private industries in natural substances and beneficial microorganisms able to boost vegetables and ornamentals productivity in a sustainable way. Protein hydrolysates (PHs) and arbuscular mycorrhiza fungi (AMF) are two important groups of plant biostimulants. PHs are generally applied as foliar sprays or near the roots, whereas, AMF are applied as powder, pellet, gel and seed coating. PHs and AMF are widely used in greenhouse crops largely for improving plant nutrient uptake, growth, yield and fruit quality, and also for their ameliorating effect on crop tolerance to abiotic stressors. In the current review article, we give an update about the recent advances in the biostimulant properties of PHs and AMF on vegetables, flower and ornamental crops performance. The agronomical and physiological processes conferring tolerance and/or resistance to several environmental stresses in biostimulant-treated plants will be also elucidated.

Lettuce (Lactuca sativa L.) is one of the most popular leafy vegetables, appreciated globally as a low-calorie food with bioactive compounds. The application of a low dose of abiotic stress is considered a sustainable pre-harvest strategy to modify the nutraceutical value of horticultural products. In this work, we explored the response of two differently colored (red or green) baby leaf lettuce varieties to four NaCl concentrations in the nutrient solution (from 1 to 30 mM), using a full factorial design. We focused on leaf morphological parameters and possible phytochemical enhancement of the main polyphenols and anthocyanins, analyzed by LC-MS. The response to low-to-moderate salt stress exposure was affected mainly by salt concentration for leaf traits or by the cultivar for leaf color, with very limited factors’ interactions. Multivariate analysis indicated a predominant role of the genotypic factor in shaping differences in the two weeks growing cycle for baby leaf lettuce. Phytochemically, different dose–response models to sub-optimal saline conditions may be applied to the various compounds. A significant hormetic stimulation was present only for cyanidin-malonyl glucoside, the main anthocyanin present in the red cultivar.

Recent studies in the agronomic field indicate that the exogenous application of polyphenols can provide tolerance against various stresses in plants. However, the molecular processes underlying stress mitigation remain unclear, and little is known about the impact of exogenously applied phenolics, especially in combination with salinity. In this work, the impacts of exogenously applied chlorogenic acid (CA), hesperidin (HES), and their combination (HES + CA) have been investigated in lettuce (Lactuca sativa L.) through untargeted metabolomics to evaluate mitigation effects against salinity. Growth parameters, physiological measurements, leaf relative water content, and osmotic potential as well as gas exchange parameters were also measured. As expected, salinity produced a significant decline in the physiological and biochemical parameters of lettuce. However, the treatments with exogenous phenolics, particularly HES and HES + CA, allowed lettuce to cope with salt stress condition. Interestingly, the treatments triggered a broad metabolic reprogramming that involved secondary metabolism and small molecules such as electron carriers, enzyme cofactors, and vitamins. Under salinity conditions, CA and HES + CA distinctively elicited secondary metabolism, nitrogen-containing compounds, osmoprotectants, and polyamines.

Various products are used to mitigate the negative effects of abiotic stress in olive trees. The aim of the research was to examine an anti-transpirant product (Vapor Gard®, V) and a kaolin- based product (Manisol, K) effect on the growth of two-year-old olive tree seedlings under high temperature. The study was conducted in a greenhouse on trees of a native cultivar of Campania (cv. Salella) grown in pot during the growing season from May to September 2020. The experimental design included two products: di-1-p-menthene (product V) and kaolin (product K), applied five times at 20 day intervals compared with a control. The following biometric, physiological, and nutraceutical parameters were evaluated: stomatal conductance, chlorophyll a fluorescence, Soil Plant Analysis Development (SPAD) index, relative water content (RWC), shoots growth, total leaf area per plant, trunk cross-sectional area, dry matter partitioning, total polyphenols, and antioxidant activity. The results obtained showed that the application of di-1-p-menthene (V) was able to induce a significant improvement of shoots growth (+37.22%) and trunk cross-sectional area (+46.60%) and a reduction of the stomatal conductance and an increase of leaf RWC values. Application with kaolin had positive effects on the total polyphenol content, with an increase over the control of 240.33% and higher antioxidant activity values. Further studies are necessary to determine the effect of these products on the biometric, physiological and nutraceutical parameters of mature olive trees cultivated in open field conditions.

Salinity is a major concern in several ecosystems and has a significant impact on global agriculture. To increase the sustainability of horticultural food systems, better management and usage of saline water and soils need to be supported by knowledge of the crop-specific responses to tolerable levels of salinity. The aim of this work was to study the effects of mild salinity on morphological growth and development, leaf color, mineral composition, antioxidant activities, and phenolic profile of sweet basil (Ocimum basilicum L.). Plants grew in hydroponics and were exposed to three nutrient solutions (NSs) differing in the NaCl concentration (either 0, 20, or 40 mM). Inhibitory effects on leaf area, fresh yield, and shoot biomass were evident starting from the lowest NaCl concentration, and they became more severe and wide-ranging at 40 mM, also affecting height and root-to-shoot ratio. Salinity increased the nutritional quality in terms of antioxidant activity and polyphenols in leaves, with a reduction in macroelements at 40 mM NaCl. Moreover, the two mild NaCl concentrations specifically modified the concentration of various phenolic acids in leaves. Overall, the use of a slightly saline (20 mM) NS could be tolerated by basil in hydroponics, strongly ameliorating the nutritional profile in the face of relative yield loss. Considering the significantly higher accumulation of bioactive compounds, our work implies that the use of low-salinity water can sustainably increase the nutritional value and the health-promoting features of basil leaves.

Recently the European Union decided to reshape the existing Fertilizers Regulations, under the new regulation that plant biostimulants “shall be a CE marked fertilising product stimulating plant nutrition processes independently of the product’s nutrient content with the sole aim of improving one or more of the following characteristics of the plant and the plant rhizophere or phyllosphere: nutrient use efficiency, abiotic tolerance and product quality”. Plant biostimulants can be divided in two major categories, the non-microbial biostimulants including bioactive substances such as humic acids, protein hydrolysates from vegetal and animal origin as well as seaweed extracts. The second category is the microbial biostimulants including arbuscular mycorrhiza fungi (AMF) and plant growth promoting rhizobacteria belonging to the genera Azotobacter, Azospirillum and Rhizobium spp. In the present paper several case studies on important greenhouse vegetables such as tomato, spinach, zucchini squash and cucumber were reported in order to demonstrate how the application of non-microbial and microbial plant biostimulants can modulate the quality of the product. The application of protein hydrolysate and seaweed extracts improve the fresh yield of both tomato and spinach but differently modulated the quality characteristics in particular lycopene, total ascorbic acid, phenols and nitrate. The application of microbial biostimulant in particular AMF containing Rhizophagus irregular and Funneliformis mosseae was able to improve the macro- and microminerals profile in zucchini squash and cucumber. The present paper concludes by proposing future research toward enhancing product quality of greenhouse vegetables by optimizing biostimulants application and composition.

In many irrigated regions of Mediterranean areas, vegetable farmers are forced to use low quality water (often with elevated salinity) for their crops with important losses in productivity. Sweet basil (Ocimum basilicum L.) is one of the most important aromatic herbs cultivated in Italy under both open-field and protected conditions. The application of endophytic fungi such as mycorrhizal fungi and Trichoderma could be an efficient tool to mitigate the detrimental effect of salinity. A greenhouse experiment was carried out to assess the influence of co-inoculation of endophytic fungi and plant growth promoting rhizobacteria on yield and quality traits under non-saline (1 mM NaCl) and saline (40 mM NaCl) conditions. Increasing the NaCl concentration in the nutrient solution in both inoculated and non-inoculated plants decreased the yield and growth parameters but increased the quality traits in particular the hydrophilic and lipophilic antioxidant activities and total phenols. The microbial-based biostimulant markedly enhanced the marketable fresh yield by 17.0% compared to control plants. The better crop performance of inoculated basil has been attributed to a better pigment biosynthesis (i.e., higher SPAD index). On the other hand, the nitrate content in microbial biostimulant basil plants was significantly reduced by 16.1%, whereas the total phenols increased by 7.7% compared to untreated plants. Overall, the use of beneficial microorganisms could be adopted as a sustainable tool in vegetable cropping systems to mitigate the detrimental effect of saline water.

The unavailability of fresh water is one of the main concerns for horticulture nowadays and it is supposed to get worse in the coming future. Some crops are more vulnerable than others to drought stress such as leafy vegetables. It is therefore essential to identify and select cultivars that can overcome this kind of abiotic stress with limited or no substantial reduction in final yield, and to do it in a fast and effective way. High throughput phenotyping combined with advances in genome sequences provide efficient and reproducible approaches that are facilitating the discovery of genes and cultivars with improved plant performance under sub-optimal conditions. Drought resistance of two different Salanova® cultivars, ‘Aquino’ (green butterhead) and ‘Barlach’ (red butterhead), was tested, by using PlantScreen™, a high-throughput non-invasive imaging platform developed at Photon Systems Instruments (PSI, Czech Republic). The two cultivars performed similarly in both control (70% soil water content) and mild drought stress conditions (40% soil water content). The results demonstrated that ‘Aquino’ grew faster in control conditions at early growth phase, while in later phase it is the red ‘Barlach’ that reached larger biomass. In drought conditions growth performance of both cultivars was rapidly compromised. However, ‘Barlach’ grew better and had improved biomass in both control and mild-drought stress conditions in comparison with ‘Aquino’. Light curve protocol was used to address light use efficiency of the two cultivars. Interestingly, we observed a rapid decline in PS II operating efficiency already three days upon mild drought stress initiation. Nevertheless, there was no obvious difference in the performances between the two cultivars. In conclusion, the results of quantitative analysis of plant growth and photosynthetic performance, allowed to set up a protocol for high-throughput image-based analysis of different morpho-physiological traits associated with the early phase of drought response.

A greenhouse experiment was carried out during the winter growing season in 2015 in Ladispoli (central Italy) to assess the influence of Trichoderma atroviride strain AT10 on shoot fresh biomass and resistance against the soilborne pathogen Sclerotinia spp. of lettuce crop (Lactuca sativa L. ‘Canasta’) grown in a naturally infested soil. T. atroviride strain AT10 was applied five times (1, 11, 24, 34 and 49 days after transplanting) by drip irrigation at a rate of 1 kg ha-1 for each application. Lettuce drop caused by Sclerotinia spp. appeared at 49 days after transplanting where untreated plants (control) showed a higher mortality than plant treated with T. atroviride (4.0 vs. 0.9%). The disease incidence increased significantly at 56 days after transplanting with higher value in control plots than in plots treated with T. atroviride AT10 (4.1 vs. 2.4%). At the end of the trial (61 days after transplanting) the disease incidence reached 8.5% in control plot and 3.3% in treated plots. The efficacy of Trichoderma treatments in reducing the disease incidence in comparison with control treatment was calculated with the Abbott’s formula and varied from 42.1 to 77.2%. The antagonistic activity of T. atroviride strain AT10 against Sclerotinia was demonstrated through in vitro tests. At harvest, lettuce plants inoculated with T. atroviride strain AT10 had a 13% higher shoot fresh weight than untreated plants indicating a phytostimulation action of the endophytic fungus.

Winter and summer nitrate/nitrite concentrations in 11 salad vegetables were surveyed using a validated HPLC-DAD method. Nitrate was highest in rocket, both in winter (x = 3974 mg kg−1 fw) and summer (x = 3819 mg kg−1 fw). High nitrate accumulators included spinach, purslane, chards, dill, coriander and parsley. Wide intra-species variability and levels in excess of permitted maxima highlighted the importance of monitoring vegetable production methods to protect consumer health. Occurrence of detectible nitrite (14–352 mg kg−1 fw) was most frequent in winter head cabbage. Three additional experiments examined the seasonal effects of nitrogen (N) fertilization rate, application method, formulation and postharvest storage on nitrate and nitrite levels in lettuce, rocket and spinach. Violation of current nitrate limits is likely when total N exceeds 200 kg ha−1, particularly in rocket and spinach. Postharvest nitrate reduction requires exogenous microbial nitrate reductase activity, which is unlikely to be achieved without visible loss of quality.

Consumer demand has been increasing and many vegetable farmers have oriented their production plans towards baby leaf vegetables such as lettuce. The management of the nutrient solution as well as the growing conditions could significantly affect the yield and quality of leafy vegetable crops. The aim of the present work was to determine the effects of increasing the level of salinity in the nutrient solution (1, 10 or 20 mM NaCl) during two consecutive growing seasons (spring and autumn) on the yield and quality of Lactuca sativa L. var. acephala grown in floating raft culture. Increased salinity in the nutrient solution decreased marketable yield and dry biomass with more detrimental effect during the warm season. The percentage of yield reduction in comparison to the non-saline control was 7 and 20% in the spring season and 4 and 13% in the autumn growing season at 10 and 20 mM NaCl, respectively. Plants grown in the spring season exhibited higher yield and dry biomass but lower leaf quality than those grown in the autumn season. When averaged over salinity level the lipophylic antioxidant activity, total ascorbic acid, phenols and nitrate contents were significantly increased by 7.1, 20.1, 19.4 and 24.4%, respectively, in plants grown in spring as compared to autumn growing season. The floating system could be considered an efficient and low-cost tool to improve quality aspects through proper management of the salt concentration in the nutrient solution with an acceptable yield reduction.

Currently, climate change is affecting considerably the availability of freshwater for agriculture, increasing the need for the optimization of crop water use efficiency. Attempts to use VPD (vapor pressure deficit) modulation to reduce water consumption have been made. However, the effects of VPD on leaf stomatal and hydraulic traits, and on possible tradeoffs between photosynthetic carbon gain and transpiration, are rarely reported. We analyzed photosynthesis (gas-exchange, photochemistry) stomatal and hydraulic-related traits of green (G) and red (R) butterhead lettuce (Lactuca sativa L.) grown under low and high VPD (LV, HV) in a controlled environment. Our results showed that plants developed a higher number of small stomata under LV, allowing better regulation over opening/closing mechanisms and thus increasing net photosynthesis by 18%. LV plants also achieved better performance of the photosystem II and a more efficient water use (increments in ΦPSII and iWUE by 3% and 49%), resulting in enhanced plant growth and reduced need for irrigation. Significant differences between G and R plants were limited to a few traits, and the physiological response under the two VPDs did not show cultivar-specific response. We discuss the role of VPD management as necessary to maximize crop water use by harmonizing photosynthesis and transpiration.

Increasing attention is being given to the development of innovative formulations to substitute the use of synthetic chemicals to improve agricultural production and resource use efficiency. Alternatives can include biological products containing beneficial microorganisms and bioactive metabolites able to inhibit plant pathogens, induce systemic resistance and promote plant growth. The efficacy of such bioformulations can be increased by the addition of polymers as adjuvants or carriers. Trichoderma afroharzianum T22, Azotobacter chroococcum 76A and 6-pentyl-α-pyrone (6PP, a Trichoderma secondary metabolite) were administrated singularly or in a consortium, with or without a carboxymethyl cellulose-based biopolymer (BP), and tested on sweet basil (Ocimum basilicum L.) grown in a protected greenhouse. The effect of the treatments on basil yield, photosynthetic activity and secondary metabolites production was assessed. Photosynthetic efficiency was augmented by the applications of the bioformulations. The applications to the rhizosphere with BP + 6PP and BP + T22 + 76A increased the total fresh weight of basil by 26.3% and 23.6%, respectively. Untargeted LC-MS qTOF analysis demonstrated that the plant metabolome was significantly modified by the treatments. Quantification of the profiles for the major phenolic acids indicated that the treatment with the T22 + 76A consortium increased rosmarinic acid content by 110%. The use of innovative bioformulations containing microbes, their metabolites and a biopolymer was found to modulate the cultivation of fresh basil by improving yield and quality, thus providing the opportunity to develop farming systems with minimal impact on the environmental footprint from the agricultural production process.

Hydroponics growing systems often contain excessive nutrients (especially nitrates), which could lead to a quality loss in ready-to-eat leafy vegetables and posing a health risk to consumers, if managed inadequately. A floating raft system was adopted to assay the production and quality performance of lettuce (Lactuca sativa L. cv ‘Maravilla De Verano Canasta’) deprived of the nutrient solution by replacement with only water, three and six days before harvest. Yield and quality parameters, mineral composition, pigments, organic acids, amino acids profile, soluble proteins, and carbohydrate content were determined. Nutrient solution deprivation six days before harvest resulted in a significant reduction in leaf nitrate (−53.3%) concomitant with 13.8% of yield loss, while plants deprived of nutrient solution three days before harvest increased total phenols content (32.5%) and total ascorbic acid (102.1%), antioxidant activity (82.7%), anthocyanins (7.9%), sucrose (38.9%), starch (19.5%), and γ-aminobutyric acid (GABA, 28.2%), with a yield reduction of 4.7%, compared to the control. Our results suggest that nutrient solution deprivation three days before harvest is a successful strategy to reduce nitrate content and increase the nutritional quality of lettuce grown in floating raft systems with negligible impact on yield. These promising results warrant further investigation of the potential effect of nutrient solution deprivation on the quality attributes of other leafy vegetables cultivated in floating raft systems and in a “cascade” growing system.

Lettuce (Lactuca sativa L.) is a winter-spring leafy vegetable, but the high demand for fresh products available year-round requires off-season production. However, the warm climate of the Mediterranean areas can impair the summer production of lettuce, thus requiring the adoption of genotypes tolerant to high irradiance as well as useful agronomic strategies like shading net installations. The aim of our research was to assess the leaf morpho-physiological and anatomical changes, in addition to productive responses, of four lettuce cultivars (‘Ballerina’, ‘Maravilla De Verano Canasta’, ‘Opalix’, and ‘Integral’) grown under shading and non-shading conditions to unveil the adaptive mechanisms of this crop in response to sub-optimal microclimate (high irradiance and temperature) in a protected environment. Growth and yield parameters, leaf gas exchanges, chlorophyll fluorescence and morpho-anatomical leaf traits (i.e., leaf mass area, stomatal density and epidermal cell density) were determined. Under shading conditions, the fresh yields of the cultivars ‘Ballerina’, ‘Opalix’ (‘Oak leaf’) and ‘Integral’ (‘Romaine’) increased by 16.0%, 26.9% and 13.2% respectively, compared to non-shading conditions while both abaxial and adaxial stomatal density decreased. In contrast, ‘Canasta’ under non-shading conditions increased fresh yield, dry biomass and instantaneous water use efficiency by 9.6%, 18.0% and 15.7%, respectively, while reduced abaxial stomatal density by 30.4%, compared to shading conditions. Regardless of cultivar, the unshaded treatment increased the leaf mass area by 19.5%. Even though high light intensity and high temperature are critical limiting factors for summer lettuce cultivation in a protected environment, ‘Canasta’ showed the most effective adaptive mechanisms and had the best production performance under sub-optimal microclimatic conditions. However, greenhouse coverage with a white shading net (49% screening) proved to be a suitable agricultural practice that ensured an adequate microclimate for the off-season growth of more sensitive cultivars ‘Ballerina’, ‘Oak leaf’ and ‘Romaine’.

The use of plant biostimulants contributes to more sustainable and environmentally friendly farming techniques and offers a sustainable alternative to mitigate the adverse effects of stress. Protein hydrolysate-based biostimulants have been described to promote plant growth and reduce the negative effect of abiotic stresses in different crops. However, limited information is available about their mechanism of action, how plants perceive their application, and which metabolic pathways are activating. Here we used a multi-trait high-throughput screening approach based on simple RGB imaging and combined with untargeted metabolomics to screen and unravel the mode of action/mechanism of protein hydrolysates in Arabidopsis plants grown in optimal and in salt-stress conditions (0, 75, or 150 mM NaCl). Eleven protein hydrolysates from different protein sources were used as priming agents in Arabidopsis seeds in three different concentrations (0.001, 0.01, or 0.1 μl ml–1). Growth and development-related traits as early seedling establishment, growth response under stress and photosynthetic performance of the plants were dynamically scored throughout and at the end of the growth period. To effectively classify the functional properties of the 11 products a Plant Biostimulant Characterization (PBC) index was used, which helped to characterize the activity of a protein hydrolysate based on its ability to promote plant growth and mitigate stress, and to categorize the products as plant growth promoters, growth inhibitors and/or stress alleviator. Out of 11 products, two were identified as highly effective growth regulators and stress alleviators because they showed a PBC index always above 0.51. Using the untargeted metabolomics approach, we showed that plants primed with these best performing biostimulants had reduced contents of stress-related molecules (such as flavonoids and terpenoids, and some degradation/conjugation compounds of phytohormones such as cytokinins, auxins, gibberellins, etc.), which alleviated the salt stress response-related growth inhibition.

The management of mineral elements in agriculture is important for their nutritional role for plants and dietary value for humans, sparking interest in strategies that can increase mineral use efficiency and accumulation in plant food. In this work, we evaluated the effects of the isosmotic variations of the concentration on three macrocations (K, Ca, and Mg) in lettuce (Lactuca sativa L.). Our aim was to improve the nutritional components of this valuable dietary source of minerals. Using a full factorial design, we analyzed mineral utilization efficiency (UtE), leaf morphology, gas exchange parameters, phenolic profiles (through ultra-high performance liquid chromatography coupled to a quadrupole-time-of-flight (UHPLC-QTOF) mass spectrometry), and enzymatic activities in two phytochemically diverse butterhead lettuce varieties (red or green). Plants were fed in hydroponics with three nutrient solutions (NSs) with different ratios of K, Ca, and Mg. The variation of these minerals in the edible product was associated with alterations of the morphology and physiology of the leaves, and of the quality and functional properties of lettuce, with a trade-off between total accumulation and mineral UtE. Moreover, in non-limiting conditions of nutrient availability, significant mineral interactions were also present. The flexibility of the plant response to the different ratios of macrocations, and the observed large intraspecific variation, were adequate to provide mineral-specific phytochemical profiles to the edible product. Specifically, the full-red lettuce provided more interesting results in regard to the compositional and functional attributes of the leaves.

Lupin seeds can represent a valuable source of phenolics and other antioxidant compounds. In this work, a comprehensive analysis of the phytochemical profile was performed on seeds from three Lupinus species, including one cultivar (Lupinus albus) and two wild accessions (Lupinus cossentinii and Lupinus luteus), collected from the northern region of Tunisia. Untargeted metabolomic profiling allowed to identify 249 compounds, with a great abundance of phenolics and alkaloids. In this regard, the species L. cossentinii showed the highest phenolic content, being 6.54 mg/g DW, followed by L. luteus (1.60 mg/g DW) and L. albus (1.14 mg/g DW). The in vitro antioxidant capacity measured by the ABTS assay on seed extracts ranged from 4.67 to 17.58 mg trolox equivalents (TE)/g, recording the highest values for L. albus and the lowest for L. luteus. The DPPH radical scavenging activity ranged from 0.39 to 3.50 mg TE/g. FRAP values varied between 4.11 and 5.75 mg TE/g. CUPRAC values for lupin seeds ranged from 7.20 to 8.95 mg TE/g, recording the highest for L. cossentinii. The results of phosphomolybdenum assay and metal chelation showed similarity between the three species of Lupinus. The acetylcholinesterase (AChE) inhibition activity was detected in each methanolic extract analyzed with similar results. Regarding the butyrylcholinesterase (BChE) enzyme, it was weakly inhibited by the Lupinus extracts, in particular, the highest activity values were recorded for L. albus (1.74 mg GALAE/g). Overall, our results showed that L. cossentinii was the most abundant source of polyphenols, consisting mainly in tyrosol equivalents (5.82 mg/g DW). Finally, significant correlations were outlined between the phenolic compounds and the in vitro biological activity measured, particularly when considering flavones, phenolic acids and lower-molecular-weight phenolics.

The growing interest in healthy foods has driven the agricultural sector towards eco-friendly implementation to manage biotic and abiotic factors in protected environments. In this perspective, anti-insect nets are an effective tool for controlling harmful insect populations concomitantly with reducing chemicals’ interference. However, the low porosity of nets necessary to ensure high exclusion efficiency for a designated insect leads to reduced airflow, impacting the productivity and quality attributes of vegetables. The evidence presented in this dataset pertains to the content of total nitrogen, minerals (i.e., NO3, K, PO4, SO4, Ca, Mg, Cl, and Na), and organic acids (i.e., malate and citrate) of zucchini squash (Cucurbita pepo L. cv. Zufolo F1) in leaves and fruits grown with two anti-insect nets with different porosities (Biorete® 50 mesh and Biorete® 50 mesh AirPlus), is and analyzed by the Kjeldahl method and ion chromatography (ICS3000), respectively. Data of total nitrogen concentration, macronutrients, and organic acids provide in-depth information about plants’ physiological response to microclimate changes induced by anti-insect nets.

Parsley is an aromatic herb native to the Mediterranean region and treasured for its phytochemical profile and bioactive properties. Developmental stage at harvest is a factor that modulates the nutritional quality of vegetables, including young greens. Accordingly, an experiment under strictly controlled conditions was carried out to compare the mineral macronutrient and phytochemical composition as well as the antioxidant activity of plain-leaf parsley (Petroselinum crispum cv. Comune 2) at two different harvest maturity stages, microgreens and baby greens. Macronutrients, carotenoids (lutein and β-carotene) and polyphenols were quantified through ion chromatography, high-performance liquid chromatography with a diode-array detector (HPLC-DAD) and UHPLC-Q-Orbitrap high-resolution mass spectrometry (HRMS), respectively. Microgreens accumulated more potassium and phosphorus, whereas baby greens accumulated more calcium and magnesium, and 65.5% less nitrate. In addition, microgreens provided 1.8-fold more lutein and 2.8-fold more β-carotene, whereas baby greens provided 183.6% more total ascorbic acid, 64.2% more total polyphenols and 170.3% higher hydrophilic antioxidant activity. Based on the culinary and phytonutritive scope of the consumers, different harvest maturity stages can be opted for and production schemes designed. Future studies are warranted to appraise the importance of ontogeny as a determinant factor for the composition and bioactive value of additional micro-herb genotypes, including underutilized Mediterranean species.

Human iodine (I) shortage disorders are documented as an imperative world-wide health issue for a great number of people. The World Health Organization (WHO) recommends I consumption through ingestion of seafood and biofortified food such as vegetables. The current work was carried out to appraise the effects of different I concentrations (0, 50, 250, and 500 mg L−1), supplied via foliar spray on curly endive grown in the fall or spring–summer season. Head fresh weight, stem diameter, head height, and soluble solid content (SSC) were negatively correlated to I dosage. The highest head dry matter content was recorded in plants supplied with 250 mg I L−1, both in the fall and spring–summer season, and in those cultivated in the fall season and supplied with 50 mg I L−1. The highest ascorbic acid concentration was recorded in plants cultivated in the spring–summer season and biofortified with the highest I dosage. The highest fructose and glucose concentrations in leaf tissues were obtained in plants cultivated in the spring–summer season and treated with 250 mg I L−1. Plants sprayed with 250 mg I L−1 and cultivated in the fall season had the highest I leaf concentration. Overall, our results evidently suggested that an I application of 250 mg L−1 in both growing seasons effectively enhanced plant quality and functional parameters in curly endive plants.

Sweet basil (Ocimum basilicum L.) is an economically important leafy vegetable especially in Mediterranean countries. In Italian gastronomy, the large elliptical leaves of the Genovese type are mostly used for the well-known pesto sauce, and almost all (>90%) professional production is for the food industry. The growing demand for fresh leaves with standardized technological and sensory characteristics has prompted basil producers to adopt advanced cultivation methods such as the floating raft system (FRS). The aim of this study was to evaluate the productive, qualitative, and physiological performance of three Genovese basil cultivars (“Aroma 2,” “Eleonora,” and “Italiano Classico”) in two successive harvests and at two densities (159 and 317 plants m–2). Caffeic, chicoric, rosmarinic, and ferulic acid were determined through the high-performance liquid chromatography (HPLC) system, whereas the extraction and quantification of the volatile organic compounds (VOCs) were performed by solid-phase microextraction (SPME) and gas chromatography coupled to a mass spectrometer (GC/MS). “Aroma 2” showed the highest fresh yield and photosynthetic rate together with the lowest nitrate content. For all the tested cultivars, the higher density, while reducing the number of leaves per plant, resulted in higher fresh and dry production per unit area, without altering the aroma profile. Successive harvests resulted in a significant increase in both the yield (37.5%) and the total phenolic acids (75.1%) and favored Eucalyptol and 1-octen-3-ol accumulation (+25.9 and +15.1%, respectively). The here presented comprehensive and multifactorial assessment of the productive and qualitative response of basil provides evidence of the positive effects (from biomass to specialized metabolites) that can be obtained from the management of the pre-harvest factors in soilless cultivation. In addition, it also highlights the role and constraints of the genetic factor in the observed response. We also discuss the implications of our work considering the impact for the food processing industry. Future research may explore the phenolic acids accumulation as a possible fortification means to extend the pesto sauce shelf life, reducing the need of added antioxidants and thermal processing.

Despite scientific evidence supporting the biostimulant activity of protein hydrolysates (PHs) derived from vegetal or animal sources, the morpho-physiological and biochemical mechanisms underlying the biostimulant action of PHs from plant biomass or animal by-products are still poorly explored. Accordingly, we performed a greenhouse experiment for assessing the morphological, physiological and biochemical responses of sweet basil (Ocimum basilicum L.) to three nitrogen equivalent rates (0.05, 0.15, and 0.25 g N/kg) of an animal-derived protein hydrolysate (A-PH) and a vegetal-derived protein hydrolysate (V-PH). The V-PH and A-PH applications determined a quadratic-dose response regarding the number and area of leaves and the shoot fresh and dry weight, with the best results obtained using V-PH at the N equivalent rates of 0.05 and 0.15 g N/kg. Improvement of shoot fresh weight with V-PH foliar application at the rate of 0.15 g N/kg was associated with a higher leaf CO2 assimilation and water use efficiency, with a concomitant higher uptake and translocation of K, Mg, and S in leaf tissue. The excessive accumulation of Na, Cl, and some amino acids (e.g., proline) under A-PH applications above 0.05 g N/kg induced a rapid decrease in plant photosynthetic performance, growth, and biomass production. The plants treated with A-PH at a higher dosage appeared to activate an alternative pathway involving the synthesis of alanine and GABA for storing excess ammonia, buffering cytoplasmic acidosis, and counteracting the negative effects of Na and Cl at toxic levels. The above findings demonstrated the potential benefits of protein hydrolysate application in agriculture, especially of vegetal-derived PHs, and highlighted the need to understand dose-dependent effects in order to optimize crop response.

Grafting is increasingly becoming an indispensable tool that minimizes the risks associated with intensive vegetable production systems, including soil-borne diseases. This study assesses the performance of two cherry tomato hybrids (‘Cheramy’ and ‘Sheeja’) grafted onto three tomato and five eggplant local rootstock genotypes (cultivated/wild) under Ralstonia solanacearum (bacterial wilt)-infested greenhouse soil. The impact of grafting on growth, yield and fruit physical quality was mainly influenced by the response of rootstocks to disease resistance. The non-grafted plants of both the cultivars were severely affected by bacterial wilt, thus presenting high susceptibility to disease. Eggplant rootstocks imparted moderate to high resistance against bacterial wilt in both the scions, while tomato (cultivated or wild) rootstocks did not improve disease resistance, except ‘Anagha’, which provided resistance to scion cv. ‘Cheramy’. In general, scion cv. ‘Cheramy’, grafted or non-grafted, showed superior growth, yield and fruit quality compared to ‘Sheeja’. The most productive graft combinations for both the cultivars involved resistant rootstocks, i.e., ‘Sheeja’ onto eggplant rootstock ‘Surya’, and ‘Cheramy’ onto tomato rootstock ‘Anagha’. Fruit quality attributes such as ascorbic acid and lycopene contents were considerably higher, and the total soluble solids (TSS) content was considerably lower in scion cv. ‘Cheramy’, whether grafted or non-grafted, than those involving scion cv. ‘Sheeja’. The grafting effect on fruit chemical quality attributes was not promising, except grafting ‘Sheeja’ onto ‘Sopim’ for TSS, ‘Sheeja’ onto ‘Sotor’ for lycopene and ‘Cheramy’ onto ‘Ponny’ for total phenols, though no clear connection with disease incidence was in these grafts. Conclusively, eggplant rootstock imparted wilt resistance, while both eggplant and tomato rootstock grafting was beneficial to both scion cultivars in boosting the overall production and economic gains, especially for ‘Cheramy’ grafted onto ‘Anagha’ rootstock under bacterial wilt infested soil of greenhouse.

Microgreens are receiving increasing popularity as functional and healthy foods due to their nutritional value and high content of bioactive compounds. The aim of the present study was to evaluate the effects of nutrient deprivation through the regulation of nutrient solution (NS) feeding days on the plant growth and chemical composition of spinach microgreens. For this purpose, spinach microgreens were subjected to four different fertigation treatments—namely, 0 (control), 5, 10, and 20 NS feeding days before harvesting—and harvested tissues were evaluated with regard to fresh and dry yield, color of true leaves, antioxidant activity, and chlorophyll, carotenoid, and phenolic compound contents. The results of our study revealed that prolonged NS feeding (20 NS) resulted in the highest fresh yield and photosynthetic pigment contents (chlorophylls, lutein, and β-carotene). In contrast, mineral concentrations (P, K, Ca, and Mg) were the lowest for the 20 NS, whereas the control (0 NS) and 5 NS recorded the highest concentrations. Apart from that, spinach microgreens subjected to 10 NS treatment recorded 70.7% less nitrates, better mineral concentrations, 7.0% higher total ascorbic acid, similar polyphenol contents, higher DM%, and only 12.6% yield decrease compared to 20 NS treatment. In conclusion, although the highest overall fresh yield was recorded with the 20 NS treatment, the highest nitrate concentrations and the lowest mineral concentrations may raise food safety concerns. On the other hand, 10 NS treatment seems to be the most promising, since it combined high yields with high mineral concentrations and low nitrate concentrations, without compromising bioactive compound (e.g., polyphenols) contents, presenting a cost-effective and sustainable practice for microgreen cultivation.

Rising temperature and solar radiation drive the mobilization and depletion of crown-deposited metabolites harnessed for asparagus spear regeneration during the spring harvest season. We presently examined how successive same-season harvests impact the sensory, nutritive and bioactive composition of select green asparagus genotypes. Soluble carbohydrates were analyzed by HPLC-RI, organic acids and polyphenols by HPLC-DAD and metals by ion chromatography. Higher sugars and lower acids accentuated sweetness and lower polyphenols contributed to reduced astringency at the beginning of the harvest season. This trend was reversed as the season advanced and spear sensory quality was compromised by declining sugars and rising acids; however, functional quality improved as antioxidant capacity increased along with the concentrations of quercetin-3-O-rutinoside (rutin) and ascorbic acid. The compositional changes presently described were uniform across all genotypes examined and thus contribute toward our understanding of seasonal variation in the sensory and functional quality of this acclaimed health-promoting product.

Neglected and underutilized species (NUS) offer largely unexplored opportunities for providing nutritious plant food, while making agro-ecosystems more diverse and resilient to climate change. The aim of this work was to explore the potential of two typical Mediterranean underutilized species, purslane and borage, as novel vegetable product (microgreens). Micro-scale production of edible plants is spreading due to the simplicity of their management, rapid cycle, harvest index, and phytochemical value of the edible product. Microgreens, therefore, represent an opportunity to link NUS, nutrition, and agricultural and dietary diversification. By analyzing yield, antioxidants activities, mineral composition, and main phenolic acids and flavonoids, our work indicated that the two species provide interesting results when compared with those reported for crops and horticultural species. Specifically, purslane should be considered highly nutritional due to the amount of phenolic compounds and ascorbic acid, and to potential good β-carotene bioavailability. Borage microgreens have a very high fresh yield and a more composite and balanced phenolic profile. In conclusion, our work provided evidence for implementing new ways to expand the NUS market-chains and for developing added-value food products.

Mineral elements are essential for plant growth and development and strongly affect crop yield and quality. To cope with an everchanging environment, plants have developed specific responses to combined nutrient variations. In this work, we investigated the effects of multifactorial treatments with three macrocations (K, Ca, and Mg) on lettuce (Lactuca sativa L.) varieties that strongly diverge in leaf pigmentation (full red or green). Specifically, we monitored main leaf parameters and metabolomics profiles of hydroponically grown plants fed with isosmotic nutrient solutions that have different proportions of macroelements. The result revealed a high biochemical plasticity of lettuce, significantly affected by the genotype, the nutrient solution, and their interaction. Our work also provided evidence and insights into the different intraspecific responses to multifactorial variation of macrocations, with two varieties having distinct strategies to metabolically respond to nutrient variation. Overall, plant adaptive mechanisms increased the phytochemical diversity between the varieties both among and within the main classes of plant secondary metabolites. Finally, our work also implies that the interaction of a pre-existing phytochemical diversity with the management of multiple mineral elements can offer added health-related benefits to the edible product specific to the variety.

Reinforcing and optimizing sustainable food production is an urgent contemporary issue. The depletion of natural mineral resources is a key problem that is addressed by recycling mined potassium and phosphorus, and nitrogen, whose production depends on very high energy input. A closed-loop approach of fertilizer use asserts the necessity for efficient management and practices of organic waste rich in minerals. Human-derived urine is an underutilized yet excellent source for nitrogen fertilizer, and, in this study, processed urine fertilizer was applied to greenhouse soilless cultivation of lettuce (Lactuca sativa L.) cv. Grand Rapids. Biomass increase, biometric parameters, soil plant analysis development (SPAD) index, minerals, and organic acids content of lettuce were analyzed. From eight different urine fertilizer products generated, K-struvite, urine precipitate-CaO, and the liquid electrodialysis (ED) concentrate supported the growth of lettuce similar to that of commercial mineral fertilizer. ED concentrate application led to the accumulation of potassium (+17.2%), calcium (+82.9%), malate (+185.3%), citrate (+114.4%), and isocitrate (+185.7%), K-struvite augmented the accumulation of magnesium (+44.9%), and urine precipitate-CaO induced the highest accumulation of calcium (+100.5%) when compared to the control, which is an added value when supplemented in daily diet. The results underlined the potential of nitrogen- and phosphate-rich human urine as a sustainable source for the fertilization of lettuce in soilless systems.

Biochar soil amendment can boost plant productivity by improving the soil's biological, chemical, and physical properties. Up to date few studies were conducted on the use of biochar as partial substitute of peat in growing substrates for the horticultural and nursey industries, even less for the production of containerized ornamentals. With the aim to evaluate the agronomical performances of conifers wood biochar as a component for peat-reduced soilless substrates for ornamental species, a greenhouse experiment was carried out on potted Murraya paniculata (L.) Jacq. Plants were grown using the following mixtures: 0, 25, and 50% (v/v). Biochar amendment of substrates significantly affected growth and ornamental quality of potted Murrayas as a decrease of plant height, leaf area, leaf numbers, flower production, biomass yield and water use efficiency was recorded when plants were grown with 50% biochar. Highest values were observed with 0 and 25% biochar. Our results seem to suggest that conifers wood biochar could be used up to 25% as component in peat-based substrates for potted Murrayas.

Protected vegetable cultivation is a fast-growing sector in which grafting plays a crucial role for success. Cucumber is predominantly grown under protected conditions. The popular slicing (mini) cucumber comprises two segments, single- and cluster-fruit-bearing. In the present study, the performance of select fruit-bearing hybrids grafted as scions onto commercial Cucurbita hybrid rootstock ‘NS-55’ was evaluated under three different low-cost protected structures in arid regions. With respect to type of protected structure, cucumber performance was superior under a naturally ventilated polyhouse (NVP) than an insect net house (INH) or a shade net house (SNH). Micro-climate parameters inside NVP (air temperature, RH and PAR) were more congenial for cucumber than those in net houses, thereby facilitating improved physiology (chlorophyll fluorescence, chlorophyll and plant water potential) and leaf mineral status. Grafting invariably improved growth and yield parameters under all protected structures. Overall plant performance was better in the grafted cluster-fruit-bearing hybrid ‘Terminator’ than the single-fruit-bearing hybrid ‘Nefer’ or their non-grafted counterparts. Furthermore, NVP was found to be superior to net houses for water productivity, and grafted plants were more water use efficient than their counterpart non-grafted plants. Thus, NVP can be considered a suitable low-cost protected structure in conjunction with grafting to boost cucumber crop and water productivity in arid regions.

A mild salinity stress (eustress) may modulate the induction of the plant defense system in horticultural crops and the synthesis of phytochemical components able to enhance plant resilience, post-harvest performance, and the nutraceutical quality of produce. However, the choice of the correct eustress type and dose to induce the synthesis of these protective phytochemicals is pivotal to avoid potential interference with plant growth and productivity. In order to study how green and red lettuce (Lactuca sativa L.) plants equilibrate the nutritional and nutraceutical components of quality with yield components, we applied iso-osmotic concentrations of three different salts (20 mM NaCl, 20 mM KCl, and 13.3 mM CaCl2, with a final total ionic concentration of 40 mM) in combination with two successive harvests in a floating raft system. The biometric parameters, mineral composition, bioactive compounds, and antioxidant activity of both cultivars were analyzed. The green cultivar had a superior response concerning biometric traits and productivity compared to the red one during the first cut but lower phytochemical content (e.g., ascorbic acid). The effect of cut order, independently of cultivar and salinity treatments, demonstrated that at the first harvest plants could redirect metabolism by increasing the lipophilic antioxidant content (LAA) at the expense of plant yield, therefore increasing plant resilience and post-harvest nutraceutical quality, whereas, at the second harvest, plants reverted principally to tissue expansion. The treatments with iso-osmotic salt concentrations did not affect K and Mg ion contents but further increased LAA and resulted only in a moderate decrease of fresh yield. The lettuce nitrate content was reduced during the second cut only when lettuce plants were treated with NaCl and especially CaCl2.

The effect of plant biostimulation on fruits of traditional tomato germplasm is largely unknown. We examined how a tropical plant-derived biostimulant impacts the nutritional, functional, and compositional characteristics of tomato fruits from four landraces, collected in the San Marzano (SM) tomato Protected Designation of Origin (PDO) region, by profiling primary and secondary metabolites. Biostimulation was not able to completely reshuffle the morpho-physiological and nutritional profile of the four landraces. Their distinct phytochemical profile indicated a genotype-specific tuning of the analyzed traits, which also included an improved yield and fruit quality. Biostimulation of SM1 and SM3 increased photosynthetic accumulation of carbohydrate reserves, improved mineral nutrient use efficiency and consequently, yield (+21% and 34%, respectively). Moreover, biostimulation augmented the nutraceutical properties of the SM2 landrace. Interestingly, the plant-derived product increased in all genotypes lycopene, but not polyphenol accumulation in fruits. Our results show the potential of biostimulatory applications towards optimizing the fruit quality of the acclaimed SM landraces, which is suitable to satisfy both the rising consumer demand for premium traditional tomatoes and the technological needs of the food industry.

Carob is a predominantly rainfed tree crop of high nutritive value and a long history of adaptation to the edaphoclimatic stress conditions of the Mediterranean. However, declining attention to the carob tree in recent decades has aggravated genetic erosion. The extantin situgermplasm varies both in terms of pod morphology and composition, reflecting the genetic and physiological divide chiefly among grafted and non-grafted material, and possibly the impact of variable agro-environments. Accordingly, the present study aimed to establish a systematic categorization of the genetic and phenotypic diversity encountered across carob germplasm identifiedin situthroughout Cyprus, a historical center of production and genetic diversity for the species. Linking pod morphology, primary and secondary metabolite profiles with genotyped source material originating in different agro-environments and crop seasons would provide a framework for interpreting (a) the interaction of these factors in configuring carob pod physicochemical constitution, and (b) the relative stability of phenotypic traits against environmental and seasonal variation. Microsatellite analysis discriminated 36 genotypes out of the 124 trees located in nine traditional agro-environmental zones and revealed low genetic diversity within the grafted germplasm. Two landraces were identified: “Tillyria,” which is widespread and predominant, and “Kountourka,” which is mainly localized to the northeastern peninsula of Karpasia. Morphological traits, such as seeds-to-pod weight ratio, pod width and thickness were principally under genetic control. Contrarily, compositional traits, particularly total phenolic content—including condensed tannins,in vitroantioxidant capacity and to a lesser extent gallic acid, organic acids and minerals were under agro-environmental control. Agro-environmental zone also modulated principally fructose and glucose; sucrose was modulated equally by genotype and agro-environment, while total sugars were under genetic control. Statistically significant differences between seasons were detected for all traits except for the seeds-to-pod weight ratio, pod length and width. Hierarchical cluster analysis corroborates that Cyprus may be divided into two major agro-environmental zones modulating the compositional properties of the carob pulp. The present study provides a comprehensive insight into the extant carob genetic resources of Cyprus and advances our understanding of how genetic, agro-environmental and seasonal factors interact in shaping carob pod morphology and composition.

Long-term manned space-exploration missions and the permanence of human colonies on orbital stations or planetary habitats will require the regeneration of resources onboard or in-situ. Bioregenerative Life Support Systems (BLSSs) are artificial environments where different compartments, involving both living organisms and physical-chemical processes, are integrated to achieve a safe, self-regulating, and chemically balanced Earth-like environment to support human life. Higher plants are key elements of such systems and Space greenhouses represent the producers' compartment. Growing plants in Space requires the knowledge of their growth responses not only to all environmental factors acting on Earth, but also to specific Space constraints such as altered gravity, ionizing radiations and confined volume. Moreover, cultivation techniques need to be adjusted considering such limitations. The type and intensity of environmental factors to be taken into account depend on the mission scenarios. Here, we summarize constraints and opportunities of cultivating higher plants in Space to regenerate resources and produce fresh food onboard. Both biological and agro-technological issues are considered briefly going through experiments both ground-based on Earth and in Space.

Currently, vegetable production systems have been changed to improve yield and quality, leading to an improvement in sustainability. In horticultural cultivation, one of the most important sectors is the seedling production in nurseries. In the past, horticultural seedlings were produced directly by farmers. Nowadays, industrialized nurseries provide seedlings characterized by a uniform growth and an early and contemporaneous development. In addition, consumer concern about the impact of food production on the environment is driving an increased demand for organic vegetables with a consequent increase of agricultural land cultivated by organic methods. Hence, there is a need to produce high-quality seedlings suitable to be cultivated in the organic farming system. Root zone management, for improving seedling quality of organic horticultural crops, remains largely unexploited, such that this review highlights some of the current research and future development priorities, providing useful information to nursery growers. In particular, we reviewed all the scientific and modern knowledge on the production of organic, healthy and vigorous seedlings including the use of: (1) compost and compost tea; (2) agroindustrial byproducts; (3) microbial and non-microbial plant biostimulants; (4) beneficial microorganisms.

In the Italian culinary tradition, young and tender leaves of Genovese basil (Ocimum basilicum L.) are used to prepare pesto sauce, a tasty condiment that attracts the interest of the food processing industry. Like other leafy or aromatic vegetables, basil is harvested more than once during the crop cycle to maximize yield. However, the mechanical stress induced by successive cuts can affect crucial parameters associated with pesto processing (leaf/stem ratio, stem diameter, and dry matter). Our research accordingly aimed to evaluate the impact of successive harvests on three field-grown Genovese basil cultivars (“Aroma 2”, “Eleonora” and “Italiano Classico”) in terms of production, physiological behavior, and technological parameters. Between the first and second harvest, marketable fresh yield and shoot dry biomass increased by 148.4 % and 172.9 %, respectively, by contrast, the leaf-to-stem ratio decreased by 22.5 %, while the dry matter content was unchanged. The increased fresh yield and shoot dry biomass at the second harvest derived from improved photosynthetic efficiency, which enabled higher net CO2 assimilation, Fv/Fm and transpiration as well as reduced stomatal resistance. Our findings suggest that, under the Mediterranean environment, “Italiano Classico” carries superior productive performance and optimal technological characteristics in line with industrial requirements. These promising results warrant further investigation of the impact successive harvests may have on the qualitative components of high-yielding basil genotypes with respect to consumer expectations of the final product.

Brassica L. microgreens are a fresh microscale vegetable crop of high antioxidant value and naturally dense in nutrients without the intervention of biofortification or genetic engineering. A climate chamber experiment on peat-based substrate was set up to test microgreens growth and accumulation of secondary metabolites in response to nutrient supplementation. Microgreens mineral content was analyzed through ion chromatography and total ascorbic acid through UV-Vis spectrophotometry, while carotenoids and phenolic acids were quantified by HPLC-DAD and UHPLC-HRMS, respectively. Brussels sprouts and cabbage yield was only reduced by 10%, while nitrate was reduced by 99% in the absence of nutrient supplementation. Rocket yield was prominently reduced by 47%, with a corresponding nitrate reduction of 118%. Brussels sprouts secondary metabolites were not improved by the absence of nutrient supplementation, whereas cabbage microgreens demonstrated a 30% increase in total ascorbic acid and a 12% increase in total anthocyanins. As for rocket, the absence of nutrient supplementation elicited an extensive increase in secondary metabolites, such as lutein (110%), β-carotene (30%), total ascorbic acid (58%) and total anthocyanins (20%), but caused a decrease in total phenolic acids. It is hereby demonstrated that growing microgreens on a commercial peat-based substrate without nutrient supplementation can be feasible for certain species. Moreover, it might elicit a species-dependent spike in bioactive secondary metabolites.