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The aim of this study was to test Posidonia oceanica (L.) Delile seagrass residues (leaves and fibers) as growing media component to improve the nutritional quality of two different brassica microgreens (Mizuna and Rapini). We hypothesized that addition of posidonia residues in the substrate would result in higher concentration of certain mineral nutrients in the edible parts of plants. Substrates were obtained by mixing leaves and fibers, each material at the rate of 25, 50 and 75% (v/v), with a peat based commercial substrate, that was also used at 100% rate as a control treatment. Two experiments were carried out (Experiment 1: Mizuna microgreens production in growth chamber conditions; Experiment 2: Mizuna and Rapini microgreens production in greenhouse conditions). Plant growth measurements and chemical analysis on edible parts (mineral tissue composition and main bioactive compounds - polyphenol, chlorophylls and carotenoids contents) were performed in order to evaluate the effects of the different substrates on growth and nutritional composition of brassica microgreens. In order to evaluate the consumer safety, daily intake, percentage of recommended daily allowance for I (RDA-I) and hazard quotient (HQ) for I intake through consumption of 50 and 100 g portions of Rapini microgreens were calculated. Posidonia in the growing media mixtures increased I and B content in edible parts of microgreens. The calculated HQ underlines the safety of these products. Results confirm the possibility to improve nutritional profile of brassica microgreens by using this natural material as a growing media component, resulting in a sustainable approach.

Landraces of ‘Carosello’ (Cucumis melo L.) are a typical expression of Apulia’s agro-biodiversity and are consumed in the same way as cucumbers. The aim of this research was to valorize the cultivation of a local variety of ‘Carosello’, extending the cultivation period and valorizing a part of the fruits that are generally wasted (endosperm). To accomplish this, a local variety called ‘Carosello leccese’ was grown in a greenhouse during the fall season under red + blue and red + blue + far red light-emitting diodes (LED) interlight. Yield, morphology, color and biochemical composition of the external and internal part of the fruit were evaluated. Although yield increased by 26% under supplemental light, the fruit quality was not influenced by LED application. However, the exocarp was greener (chlorophylls) and more yellow (carotenoids) than the mesocarp. Finally, the endosperm, which is the part of the fruit that is generally wasted, showed the highest polyphenols content, proving to be an important source of nutraceutical compounds. Therefore, it was demonstrated that the nutritional value of the endosperm is comparable or higher than the external part of the fruit, but further studies will be necessary to valorize it from a culinary perspective.

Purslane (Portulaca oleracea L.) is a wild edible plant, traditionally consumed in the Mediterranean area and recently proposed as a new ready-to-eat vegetable, it is also called the &ldquo, vegetable for long life&rdquo, because of the high contents of several healthy compounds. Although boron (B) is not considered to be essential for humans, a daily intake of about 2 mg to obtain positive effects on aging in adult men and women has been suggested. In this study, two genotypes of purslane (wild collected and commercial variety) are grown by using a hydroponic system with three boron (B) levels in the nutrient solution (NS) (0.3 mg/L&mdash, control, 3 mg/L&mdash, low level of biofortification, and 6 mg/L&mdash, high level of biofortification) in order to increase the B content in the edible parts of the plant. The crop yield, color traits, and content of glucose, fructose, total phenols, chlorophylls, carotenoids, mineral elements (Al, B, Ca, Cr, Fe, K, Mg, Mn, Na, and Zn), nitrate, and oxalate are analyzed. Independent of the genotype, the B content in edible purslane was successfully increased in comparison with the control, obtaining 1.8- to 10.7-fold higher values of B tissue concentrations by using, respectively, 3 and 6 mg/L of B in the NS without affecting crop performances. From a nutritional point of view, the average daily intake of B could be satisfied by consuming about 75 or 48 g of purslane, grown by using 3 and 6 mg/L B level in the NS, respectively. Apart from B and Fe, the content of mineral elements in edible parts of purslane was not strongly influenced by different B levels in the NS but it was affected by genotypes. A lower sugar content was found in wild purslane grown with the highest B level. A higher content of both chlorophylls and carotenoids was found in the control but only for the commercial genotype. No differences in oxalate content were observed among B levels in the NS, while only in the case of wild genotype, we found a lower nitrate content when a B concentration of 3 mg/L was used in the NS. In conclusion, we demonstrated the possibility of using the floating hydroponic system, combined with specific B concentrations in the NS composition, as a method to calibrate the B uptake in edible parts of purslane.

Tailored foods are specifically suitable for target groups of people with particular nutritional needs. Although most research on tailored foods has been focused on increasing the nutrient content in plant tissues (biofortification), in populations with specific physiological conditions, it is recommended to reduce the uptake of specific nutrients in order to improve their health. People affected by chronic kidney disease (CKD) must limit their consumption of vegetables because of the generally high potassium (K) content in the edible parts. This study aimed to define an appropriate production technique for two baby leaf vegetables, spinach (Spinacia oleracea L.) and Swiss chard (Beta vulgaris L. ssp. vulgaris), with reduced K tissue content, minimizing the negative effects on their crop performance and overall nutritional quality. Plants were grown in a hydroponic floating system. The K concentration in the nutrient solution (NS) was reduced from 200 mg/L (K200, the concentration usually used for growing baby leaf vegetables in hydroponic conditions) to 50 mg/L over the entire growing cycle (K50) or only during the seven days before harvest (K50-7d). The reduction of K in the NS resulted in a significant decrease of K tissue content in both species (32% for K50 and 10% for K50-7d, on average), while it did not, in general, compromise the crop performance and quality traits or the bioaccessibility of K, magnesium, and calcium. The production of reduced-potassium leafy vegetables is a feasible tailored nutrition approach for CKD patients in order to take advantage of the positive effects of vegetable consumption on health without excessively increasing potassium intake.

In literature, the parameters of salinity tolerance of the main cultivated species are known, but are missing for many minor species such as wild rocket, whose cultivation in many areas of southern Italy affected by salinity is growing. Therefore, a research has been carried out i) to evaluate the response to salinity in water use, water use efficiency, yield characteristics and morfological features, and ii) identify the salinity tolerance parameters of two genotypes of wild rocket: Diplotaxis tenuifolia (L.) DC and D. muralis (L.) DC. The study was carried out in the spring of 2007 and 2008 in Policoro (MT), southern Italy, under unheated plastic greenhouse conditions. Wild rocket was sown in plastic pots containing 20 dm3 of soil. For each genotype, six soil salinity levels were compared, obtained by accurately mixing before sowing the soil with 0.0, 0.5, 1.0, 2.0, 3.5 and 5.5 g dm−3 of NaCl + CaCl2 1:1 (on a weight basis). Irrigation was performed with fresh water having electrical conductivity of 0.5 dS m−1. In each year, 3 harvests were performed; water use and the main production and plant growth parameters were recorded. D. tenuifolia provided a yield 47.3% higher than D. muralis. By rising salinity, progressive decline in marketable yield and growth of the leaves was recorded, while the dry matter content increased. The increase in salinity has led to the progressive reduction of water use in both genotypes. From moderate salinity values (about 5.5 dS m−1), the reduction in yield water use efficiency as a result of increased salinity has been observed. In addition, salinity reduced specific leaf area and increased leaf succulence. Both genotypes rank among moderately salt sensitive species, according to Maas and Hoffman's model (1977). However, D. tenuifolia, with a critical threshold of 1.98 dS m−1 and a slope of 6.61% m dS−1, showed a slightly higher tolerance than D. muralis (threshold 1.34 dS m−1 and slope 7.25% m dS−1). Reduction in yield due to salinity occurred mainly for the decrease in leaf size and, secondly, number of leaves.

Compost has been recently suggested as an alternative to peat for the preparation of growing substrates in soilless cultivation systems. However, some physico-chemical properties of compost may reduce plant performance and endanger the quality of productions, in particular for possible heavy metal accumulation in edible parts. This study aims at evaluating the suitability of a municipal solid waste compost (MSWC) and a sewage sludge compost (SSC) as components of growing media for the soilless cultivation of lettuce (Lactuca sativa L.). Heavy metal content of SSC complied with legislation limits but, in MSWC, it exceeded (Cu, Pb) or was very close (Cd, Zn) to safe limits. A greenhouse experiment was carried out by cultivating four lettuce cultivars ("Maximus," "Murai," "Patagonia," and "Aleppo") in pots containing a mixture of MSWC and perlite (MSWC + P), SSC and perlite (SSC + P), or peat and perlite (peat + P), the latter used as control. Plant biometric parameters measured after 72 days of growth revealed that the yield of plants cultivated on SSC + P was similar to control plants, independently of the cultivar. Conversely, MSWC + P suppressed in general the biomass production, especially for Murai and Patagonia cultivars. Compared to peat + P, both compost-based substrates reduced the leaf accumulation of heavy metals, with a major effect in Maximus plants. The levels of Cd and Pb in the edible part were always below the safe limits imposed by European regulation. Therefore, risks of heavy metal intake in food chain associated with the replacement of peat with compost in the growing media are negligible, even when a compost with a significant amount of heavy metals is used. Besides compost quality monitoring, also an appropriate varietal choice is crucial to obtain good yields and safe products.

Peat is a non-renewable resource and its extraction contributes to the degradation of wetland ecosystems. In order to reduce the peat use in nursery, two composts prepared from yard wastes were evaluated as a substrate component for producing vegetable seedlings for transplantation. Two experiments with tomato (Solanum lycopersicum L.) cultivars ‘Naxos’ and ‘TCP 9147’ and pepper (Capsicum annuum L.) cultivars ‘Solero’ and ‘Logos’ were set up in a greenhouse. In each experiment two composts were tested: “Cp”, obtained from yard wastes + beached residues of marine plant posidonia [Posidonia oceanica (L.) Delile – 20% of total fresh weight], and “C”, obtained only from yard wastes. Each compost was mixed with commercial peat in the amount of 0 (control), 25, 50, 75 and 100% (v/v). Results from the study suggest that, for both species, the best yield was obtained with the substrate prepared by mixing the peat with 25% of Cp.

Sea fennel (Crithmum maritimum L.), an emerging halophyte species, represents a nutritious and refined food product. In this study, the effect on yield and quality of potted sea fennel grown on three posidonia (Podisonia oceanica (L.) Delile)-based composts (a municipal organic solid waste compost, a sewage sludge compost and a green compost) and a peat-based substrate was analyzed. Composts were used both pure and mixed with peat at a dose of 50% on a volume basis. We hypothesized that the halophytic nature of this plant might overcome the limitations of high-salinity compost-based growing media. The growth parameters, color traits and trace metals content (Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb and Zn) of the edible parts were compared. Independently of the substrates, the average total and edible yields were 51 and 30 g plant&minus, 1, respectively, while the average waste portion was about 41%. The use of posidonia-based compost did not affect the color traits of sea fennel plants as compared with samples grown on the commercial peat-based substrate. In general, potted sea fennel grown on both posidonia-based composts and commercial peat-based substrate appeared a good source of essential micronutrients. Only a weak reduction of Fe and Mn concentrations was observed in plants grown on posidonia-based composts, especially when used at the highest dose. Independently of the growing medium, the content of potentially hazardous trace elements (Cd and Pb) in the edible parts of sea fennel was always below the maximum admissible limits fixed by the European legislation. Results indicate that posidonia-based composts can be used as a sustainable peat substitute for the formulation of soilless mixtures to grow potted sea fennel plants, even up to a complete peat replacement.

SummaryThe disposal of seaweed [Posidonia oceanica (L.) Delile] residues represents an environmental and economic problem in the Mediterranean Basin. In this study, two composts (Cp20 and Cp60) were prepared using posidonia residues mixed at different rates [20% or 60% (w/w) on a fresh weight (FW) basis, respectively] with grapevine prunings and vegetable waste. The feasibility of their use as partial substitutes for peat in the growing media used during transplant production of melon and tomato seedlings was assessed. Growing media were prepared by mixing Cp20 or Cp60 with commercial peat at rates of 25%, 50%, or 75% (v/v). Peat at 100% (v/v) was also tested as a control. The main physical and chemical properties of these seven growing media on shoot and root FWs and dry weights (DWs), leaf areas, root morphology, and the mineral composition of shoot tissues were determined. The six growing media obtained using posidonia-based composts had adequate physical and physico-chemical properties. In particular,...

Posidonia [Posidonia oceanica (L.) Delile] is a marine phanerogam endemic of the Mediterranean Sea that grows all along the coast forming extensive underwater meadows. Senescent posidonia leaves, together with fibers (residues of rhizomes and decomposed leaves), periodically accumulate along Mediterranean beaches, covering vast areas of coast. Removal and disposal of these large volumes of plant biomasses represent a high cost for local administrations. Therefore, in this experiment, beached residues of posidonia were composted with olive pruning and green wastes with the objective to assess the efficacy of posidonia-based compost (63% on a volume basis) as a peat replacement. The compost was then mixed with a peat-based commercial substrate at rates of 0% (C0, pure peat-based commercial substrate tested as control), 25% (C25), 50% (C50), 75% (C75), and 100% (C100, pure posidonia-based compost) v/v. Mixtures were used as growing media to produce lettuce seedlings for transplant. Two lettuce cultivars (8511RZ and Satine) were tested. Main physical and chemical properties of the five growing media, shoot and root fresh and dry weight, leaf area, root morphology, and elemental leaf tissue composition were studied. Growing media containing posidonia-based compost, C25 and C50 in particular, showed good physical properties. Increasing compost proportions in the mixtures resulted in enhanced: 1) availability of macro- and micronutrients in the growing media; and 2) overall growth parameters of lettuce seedlings, in particular for the cultivar Satine. In conclusion, posidonia-based compost shows a considerable potential as a peat substitute in horticultural substrates; posidonia residues are a low-cost renewable material. In growing media for lettuce seedlings production, posidonia-based compost could be used as a complement to peat at a rate of 25% or 50% to obtain optimal physical properties and to limit the negative effects of high B content, which are typical of posidonia residues.

Posidonia oceanica (L.) Delile is the main marine seagrass endemic of the Mediterranean Sea. From September on, leaves and rhizomes detach off the marine plant and accumulate on beaches in huge amounts, forming banks on the foreshore and backshore of beaches. Offshore residues represent an environmental, economical, social and hygienic problem, because of the great disturbance to the touristic activities, citizens life in urban areas and high costs that the public administrations have to support for managing them (beach cleaning, transport and disposal of such a biomass). Nowadays, current Italian legislation (n. 75/2010) allows the use of posidonia residues as raw material for the production of compost although at a maximum rate of 20% by fresh weight of the composting mixture. High presence of sand mixed to residues after removing from beaches and high salinity levels represent at the moment the main obstacles to the large use of this biomass as raw material for composting. Studies have been conducted, in the framework of the Life09 “Posidonia Residues Integrated Management for Eco-sustainability” (P.R.I.M.E.) project, with the aim to increase the application of posidonia residues for compost production, demonstrating the possibility to effectively separate the sand from the organic material and reduce the salinity levels. Several tests have been carried out with the objective to assess the posidonia-based compost quality. Posidonia-based compost proved to be a good peat substitute for lettuce transplant production and a good growing media component for green-house tomato and lettuce in soilless conditions. According to our studies, beached posidonia wastes could represent a low cost and renewable raw material for com-posting. Posidonia-based compost presents interesting properties and can be used as horticultural growing media component.