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Currently, different strategies, including the application of bio-fertilizers, are used to ameliorate the adverse effects posed by salinity stress as the major global problem in plants. Fish waste is suggested as a novel bio-fertilizer to mitigate the effects of biotic and abiotic stresses. In this investigation, an experiment was conducted to investigate the effects by applying different concentrations (0, 5, 10, and 15% ( v / v )) of fish waste bio-fertilizer on stevia plants grown under salt stress conditions (0, 20, 40, and 60 mM of NaCl). Results showed that salinity negatively affected growth parameters, the photosynthetic pigments, the relative water content, and the chlorophyll fluorescence parameters while increased the activity of antioxidant enzymes, total phenol, hydrogen peroxide (H 2 O 2 ), malondialdehyde (MDA), proline, and total carbohydrates compared with control samples. On the other hand, the application of fish waste bio-fertilizer mitigated the effects of salinity stress by enhancing growth and mitigating stress-relative markers, especially at the highest salinity level (60 mM). Overall, fish waste bio-fertilizer could be considered a sustainable, innovative approach for the alleviation of salinity stress effects in plants and, in addition, fish waste bio-fertilizer did not cause more salinity issues, at least with the applied doses and experiment time, which is an imperative aspect.

Salinity, one of the major abiotic stresses in plants, significantly hampers germination, photosynthesis, biomass production, nutrient balance, and yield of staple crops. To mitigate the impact of such stress without compromising yield and quality, sustainable agronomic practices are required. Among these practices, seaweed extracts (SWEs) and microbial biostimulants (PGRBs) have emerged as important categories of plant biostimulants (PBs). This research aimed at elucidating the effects on growth, yield, quality, and nutrient status of two Greek tomato landraces ('Tomataki' and 'Thessaloniki') following treatments with the Ascophyllum nodosum seaweed extract 'Algastar' and the PGPB 'Nitrostim' formulation. Plants were subjected to bi-weekly applications of biostimulants and supplied with two nutrient solutions: 0.5 mM (control) and 30 mM NaCl. The results revealed that the different mode(s) of action of the two PBs impacted the tolerance of the different landraces, since 'Tomataki' was benefited only from the SWE application while 'Thessaloniki' showed significant increase in fruit numbers and average fruit weight with the application of both PBs at 0.5 and 30 mM NaCl in the root zone. In conclusion, the stress induced by salinity can be mitigated by increasing tomato tolerance through the application of PBs, a sustainable tool for productivity enhancement, which aligns well with the strategy of the European Green Deal.

Switching over to closed-loop soilless culture systems, thus preventing pollution of water resources by nitrates and saving water and fertilizers, requires accurate estimations of the mean nutrient-to-water uptake ratios. To contribute to this objective, three fruit vegetable species (tomato, eggplant, cucumber) were grown hydroponically in a floating system under identical cropping conditions to quantify species differences in nutrient uptake. The composition of the nutrient solution used to feed the crops was identical for all species. The total water consumption and the concentrations of most nutrients (K, Ca, Mg, N, P, Fe, Mn, Zn, Cu, B) in the nutrient solution and the plant tissues were measured at crop establishment and at two different crop developmental stages. The obtained data were used to determine the uptake concentrations (UCs) using two mass balance models, one based on nutrient removal from the nutrient solution and a second based on nutrient recovery in the plant tissues. The experiment was conducted in the spring-summer season. The results revealed that the nutrient uptake concentrations were substantially different between species for all nutrients except for N, while there were also significant interactions between the two methods used for their estimation of some nutrients. Thus, the UCs of N, P, Ca, and some micronutrients were significantly higher when its estimation was based on the removal of nutrients from the nutrient solution compared to recovery from plant tissues, presumably because with the first method, losses due to denitrification or precipitation could not be separated from those of plant uptake. The comparison of the three greenhouse vegetables revealed a similar UC for nitrogen, while cucumber generally showed significantly lower UCs for P and for the micronutrients Fe, Zn, and Cu at both cropping stages compared to the two Solanaceae species. The obtained results can be used to precisely adjust the nutrient supply in closed-loop soilless cultivations to the plant uptake thus avoiding both depletion and accumulation of nutrients in the root environment., Competing Interests: The authors declare no conflict of interest.

Salinity is a major stress factor that compromises vegetable production in semi-arid climates such as the Mediterranean. The accumulation of salts in the soil can be attributed to limited water availability, which can be exacerbated by changes in rainfall patterns and rising temperatures. These factors can alter soil moisture levels and evaporation rates, ultimately leading to an increase in soil salinity, and, concomitantly, the extent to which crop yield is affected by salinity stress is considered cultivar-dependent. In contrast to tomato hybrids, tomato landraces often exhibit greater genetic diversity and resilience to environmental stresses, constituting valuable resources for breeding programs seeking to introduce new tolerance mechanisms. Therefore, in the present study, we investigated the effects of mild salinity stress on the growth, yield, and nutritional status of sixteen Mediterranean tomato landraces of all size types that had been pre-selected as salinity tolerant in previous screening trials. The experiment was carried out in the greenhouse facilities of the Laboratory of Vegetable Production at the Agricultural University of Athens. To induce salinity stress, plants were grown hydroponically and irrigated with a nutrient solution containing NaCl at a concentration that could maintain the NaCl level in the root zone at 30 mM, while the non-salt-treated plants were irrigated with a nutrient solution containing 0.5 mM NaCl. Various plant growth parameters, including dry matter content and fruit yield (measured by the number and weight of fruits per plant), were evaluated to assess the impact of salinity stress. In addition, the nutritional status of the plants was assessed by determining the concentrations of macro- and micronutrients in the leaves, roots, and fruit of the plants. The key results of this study reveal that cherry-type tomato landraces exhibit the highest tolerance to salinity stress, as the landraces 'Cherry-INRAE (1)', 'Cherry-INRAE (3)', and 'Cherry-INRAE (4)' did not experience a decrease in yield when exposed to salinity stress. However, larger landraces such as 'de Ramellet' also exhibit mechanisms conferring tolerance to salinity, as their yield was not compromised by the stress applied. The identified tolerant and resistant varieties could potentially be used in breeding programs to develop new varieties and hybrids that are better adapted to salinity-affected environments. The identification and utilization of tomato varieties that are adapted to salinity stress is an important strategy for promoting agriculture sustainability, particularly in semi-arid regions where salinity stress is a major challenge.

To address the complex challenges faced by our planet such as rapidly changing climate patterns, food and nutritional insecurities, and the escalating world population, the development of hybrid vegetable crops is imperative. Vegetable hybrids could effectively mitigate the above-mentioned fundamental challenges in numerous countries. Utilizing genetic mechanisms to create hybrids not only reduces costs but also holds significant practical implications, particularly in streamlining hybrid seed production. These mechanisms encompass self-incompatibility (SI), male sterility, and gynoecism. The present comprehensive review is primarily focused on the elucidation of fundamental processes associated with floral characteristics, the genetic regulation of floral traits, pollen biology, and development. Specific attention is given to the mechanisms for masculinizing and feminizing cucurbits to facilitate hybrid seed production as well as the hybridization approaches used in the biofortification of vegetable crops. Furthermore, this review provides valuable insights into recent biotechnological advancements and their future utilization for developing the genetic systems of major vegetable crops.

Corn salad ( Valerianella locusta ) is a popular winter salad, cultivated as an ingredient for ready-to-eat salads. The application of mild salinity stress (eustress) can increase the flavor and reduce the nitrate content of certain crops but, at the same time, a wrong choice of the eustress type and dose can negatively affect the overall productivity. In this research, the effects of different isosmotic salt solutions, corresponding to two different electrical conductivity (EC) levels, were investigated on the yield and mineral composition of hydroponically grown Valerianella locusta "Elixir". Five nutrient solutions (NS) were compared, including a basic NS used as the control, and four saline NS were obtained by adding to the basic NS either NaCl or CaCl 2 at two rates each, corresponding to two isosmotic salt levels at a low and high EC level. Corn salad proved moderately susceptible to long-term salinity stress, suffering growth losses at both low and high EC levels of saline solution, except from the low NaCl treatment. Hence, it appears that mild salinity stress induced by NaCl could be employed as an eustress solution and corn salad could be cultivated with low-quality irrigation water (20 mM NaCl) in hydroponic systems.

Milk thistle besides being a highly competitive weed is cultivated as a medicinal plant, and the seeds of which have been clinically utilized in several disorders caused in liver. The present study aims to evaluate the effect of duration and storage conditions, population, and temperature on seed germination. The experiment was conducted in Petri dishes with three replications and three factors: (a) wild populations of milk thistle (Palaionterveno, Mesopotamia, and Spata) originating from Greece, (b) duration and storage conditions (5 months at room temperature, 17 months at room temperature, and 29 months in the freezer at -18 °C), and (c) temperature (5 °C, 10 °C, 15 °C, 20 °C, 25 °C, and 30 °C). All three factors significantly affected germination percentage (GP), mean germination time (MGT), germination index (GI), radicle length (RL), and hypocotyl length (HL) and significant interactions among the treatments were noted. In specific, no seed germination was recorded at 5 °C, while the populations showed higher GP and GI at 20 °C and 25 °C after 5 months of storage. Prolonged storage negatively affected seed germination although, cold storage mitigated this effect. Moreover, higher temperatures reduced MGT and increased RL and HL with the populations reacting differently in storage and temperature regimes. The results of this study should be taken into consideration when proposing the appropriate sowing date and storage conditions of the seeds used as propagation material for crop establishment. Moreover, the effects of low temperatures such as 5 °C or 10 °C on seed germination as well as the high decline rate in germination percentage over time could be utilized in the design of integrated weed management systems thereby indicating the importance of the sowing time and the suitable crop rotation system to weed control.

This study aims to explore the possibility of a reduced application of inorganic nitrogen (N) fertiliser on the yield, yield qualities, and biological nitrogen fixation (BNF) of the hydroponic common bean ( Phaseolus vulgaris L.), without compromising plant performance, by utilizing the inherent ability of this plant to symbiotically fix N 2 . Until the flowering stage, plants were supplied with a nutrient solution containing N-concentrations of either a, 100%, conventional standard-practice, 13.8 mM; b, 75% of the standard, 10.35 mM; or c, 50% of the standard, 6.9 mM. During the subsequent reproductive stage, inorganic-N treatments b and c were decreased to 25% of the standard, and the standard (100% level) N-application was not altered. The three different inorganic-N supply treatments were combined with two different rhizobia strains, and a control (no-inoculation) treatment, in a two-factorial experiment. The rhizobia strains applied were either the indigenous strain Rhizobium sophoriradicis PVTN21 or the commercially supplied Rhizobium tropici CIAT 899. Results showed that the 50-25% mineral-N application regime led to significant increases in nodulation, BNF, and fresh-pod yield, compared to the other treatment, with a reduced inorganic-N supply. On the other hand, the 75-25% mineral-N regime applied during the vegetative stage restricted nodulation and BNF, thus incurring significant yield losses. Both rhizobia strains stimulated nodulation and BNF. However, the BNF capacity they facilitated was suppressed as the inorganic-N input increased. In addition, strain PVTN21 was superior to CIAT 899-as 50-25% N-treated plants inoculated with the former showed a yield loss of 11%, compared to the 100%-N-treated plants. In conclusion, N-use efficiency optimises BNF, reduces mineral-N-input dependency, and therefore may reduce any consequential negative environmental consequences of mineral-N over-application.

The horticultural sector is seeking innovative and sustainable agronomic practices which could lead to enhanced yield and product quality. Currently, plant biofortification is recognized as a valuable technique to improve microelement concentrations in plant tissues. Among trace elements, iodine (I) is an essential microelement for human nutrition. Concomitantly, the application of biostimulants may improve overall plant production and quality traits. With the above background in mind, an experiment was designed with the aim of assessing the interactive impact of a seaweed extract-based biostimulant (SwE) (0 mL L -1 (served as control) or 3 mL L -1 (optimal dosage)) and 0, 100, 300, or 600 mg L -1 I on the growth parameters, yield, fruit quality, minerals, and functional characteristics of the tunnel-grown "Savana" strawberry. SwE foliar application improved the plant growth-related traits, total and marketable yield, fruit color parameters, soluble solids content, nitrogen (N), potassium (K), and magnesium (Mg) fruit concentrations. Furthermore, an enhancement in the fruit dry matter content, ascorbic acid, and I concentration in fruits was detected when the SwE supply interacted with a mild I dose (100 or 300 mg L -1 ). The research underlined that combining SwE application and I biofortification increased the strawberry yield and quality and enhanced the plant nutritional status variation, thereby, determining a boosted strawberry I tolerance.

The aim of the current study wat to comparatively assess the impact of different nitrogen (N) fertilization schemes on fresh pod yield and yield quality in either organically or conventionally grown common beans ( Phaseolus vulgaris L.). Prior to common bean crop establishment, the experimental field site was cultivated following either organic (a) or conventional (b) farming practices with a winter non-legume crop ( Brassica oleracea var. italica ) (BR), or (c) with field bean ( Vicia faba sp.) destined to serve as a green manure (GM) crop. At the end of the winter cultivation period the broccoli crop residues (BR) and green manure biomass (GM) were incorporated into the soil and the plots that accommodated the treatments (a) and (c) were followed by an organically cultivated common bean crop, while the conventional broccoli crop was followed by a conventionally cropped common bean crop. Additional to the plant residues (BR), sheep manure (SM) at a rate of 40 kg N ha -1 was also applied to the organically treated common beans, while the plots with a conventionally cropped common bean received 75 kg N ha -1 . Organic common bean treated with SM + BR produced smaller pods of higher dry matter and bioactive compound content, responses that are correlated with limited soil N availability. No significant variations were observed on yield components and N levels of pods cultivated under organic (SM + GM) and conventional cropping systems. Pod sugar and starch content was not influenced by the different fertilization practices. In conclusion, we have demonstrated that the combined application of SM + GM can be considered as an efficient N-fertilisation strategy for organic crops of common bean, benefiting their nutritional value without compromising yield., Competing Interests: The authors declare no conflict of interest.

The current research investigated the effects of endophytic fungi such as Trichoderma atroviride (Ta) or Ascophyllum nodosum seaweed extract (An) and their combination on growth, yield, nutritive and functional features, and mineral profile of 'Birgah' F 1 eggplant either ungrafted, self-grafted or grafted onto the Solanum torvum rootstock. Eggplant exposed to An or An+Ta had a significant increase in root collar diameter 50 days after transplanting (RCD 50 ), total yield (TY), marketable yield (MY), ascorbic acid (AA) content, Mg, Cu, and Zn concentration, and a reduction in glycoalkaloids (GLY) compared with the control. Furthermore, grafted plants had a higher TY, MY, number of marketable fruits (NMF), RCD 50 , AA, Cu, and Zn and a lower SSC, GLY, and Mg than the ungrafted plants. The combination of grafting and An+Ta significantly improved mean weight of marketable fruits (MF), plant height 50 days after transplanting (PH 50 ), number of leaves 50 days after transplanting (NL 50 ), fruit dry matter (FDM), chlorogenic acid (ClA), proteins, and K and Fe concentration. This combination also produced fruits of high premium quality as evidenced by the higher AA and ClA concentration, the lower GLY concentration, and an overall improved mineral profile.

Information about the availability of soil mineral nitrogen (N) in organic greenhouse tomatoes after the application of mobile green manure (MGM), and its impact on plant nutrient status and yield is scarce. Considering this knowledge gap, the effects of legume biomass from faba beans that are cultivated outdoors (FAB), or from feed-grade alfalfa pellets at two different doses (AAL = 330 g m -2 ; AAH = 660 g m -2 ) that were applied as MGM on the nutrition and yield of an organic greenhouse crop of tomatoes were evaluated. All of the MGM treatments increased the mineral N concentrations in the soil throughout the cropping period, and the total N concentration in tomato leaves when compared to the untreated control. FAB and AAH treatments had a stronger impact than AAL in all of the measured parameters. In addition, AAL, AAH, and FAB treatments increased the yield compared to the control by 19%, 33%, and 36%, respectively. The application of MGM, either as faba bean fresh biomass or as alfalfa dry pellets, in organic greenhouse tomatoes significantly increased the plant available soil N, improved N nutrition, and enhanced the fruit yield. However, the N mineralization rates after the MGM application were excessive during the initial cropping stages, followed by a marked decrease thereafter. This may impose an N deficiency during the late cropping period.

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.

An organic greenhouse crop of tomato was established in February following cultivation of cowpea (CP) or common bean (CB) for green pod production, or faba bean (FB) for green manuring. The vegetative residues of CP and CB were incorporated to the soil together with farmyard manure (FYM), prior to establishing the tomato crop. The FB plants were incorporated to the soil at anthesis together with either FYM or composted olive-mill waste (CO). Green manuring with FB resulted in higher soil mineral N levels during the subsequent tomato crop and higher tomato fruit yield when combined with FYM, compared to compost. The level of soil mineral N was the main restrictive factor for yield in organic greenhouse tomato. FB for green manuring as preceding crop to tomato increased significantly the level of soil mineral N and tomato yield compared to CB or CP aiming to produce green pods. The lowest tomato yield was obtained when the preceding crop was CB cultivated for green pod production. The soil mineral N was significantly higher when FYM was applied as base dressing compared with CO, despite the higher total N concentration in CO, pointing to slower mineralization rates of CO during tomato cultivation.

The vegetable production sector is currently fronting several issues mainly connected to the increasing demand of high quality food produced in accordance with sustainable horticultural technologies. The application of biostimulants, particularly protein hydrolysates (PHs), might be favorable to optimize water and mineral uptake and plant utilization and to increase both production performance and quality feature of vegetable crops. The present study was carried out on celery plants grown in a tunnel to appraise the influence of two PHs, a plant-derived PH (P-PH), obtained from soy extract and an animal PH (A-PH), derived from hydrolyzed animal epithelium (waste from bovine tanneries) on yield, yield components (head height, root collar diameter, and number of stalks), mineral composition, nutritional and functional features, as well as the economic profitability of PHs applications. Fresh weight in A-PH and P-PH treated plants was 8.3% and 38.2% higher, respectively than in untreated control plants. However, no significant difference was found between A-PH treated plants and control plants in terms of fresh weight. Head height significantly increased by 5.5% and 16.3% in A-PH and P-PH treated plants, respectively compared with untreated control ( p ≤ 0.05). N content was inferior in PHs treated plants than in untreated control. Conversely, K and Mg content was higher in A-PH and P-PH treated plants as compared to the untreated ones. Furthermore, A-PH and P-PH improved ascorbic acid content by 8.2% and 8.7%, respectively compared with the non-treated control ( p ≤ 0.001). Our results confirmed, also, that PHs application is an eco-friendly technique to improve total phenolic content in celery plants. In support of this, our findings revealed that animal or plants PH applications increased total phenolics by 36.9% and 20.8%, respectively compared with untreated plants ( p ≤ 0.001).