This review integrates current knowledge on how greenhouse conditions regulate the nutritional quality and shelf life of tomato, cucumber, and sweet pepper. Preharvest environmental factors jointly shape fruit composition, firmness, and storage performance through their control of photosynthesis, assimilate partitioning, and structural stability. Across all variables, light intensity and fruit temperature emerge as the dominant determinants of overall quality and shelf life potential. Relative air humidity (RH), irrigation regime, and nutrient balance primarily affect firmness, water loss, and physiological disorders, while CO₂ enrichment, shading, and mineral or biostimulant inputs exert secondary yet consistent effects. Comparative evaluation shows that tomato is most sensitive to temperature and RH, cucumber to water status and epidermal stress, and sweet pepper to radiation for color and antioxidant development. These distinctions confirm that no single climatic optimization can be universally applied, and management must therefore target species-specific physiological constraints to sustain both nutritional excellence and storage performance. Major knowledge gaps remain, particularly regarding the combined effects of interacting environmental drivers and the integration of physiological responses with postharvest behavior. Future research should adopt multifactorial designs and predictive modeling to support climate-smart greenhouse strategies that optimize quality and storability under variable growing conditions.

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.

Drought stress is a critical abiotic constraint on agricultural productivity, particularly affecting crops like pepper (Capsicum annuum L.), which are highly susceptible to water deficits due to their physiological characteristics. The present study investigated the impact of a 40% reduction in irrigation on yield, macronutrient concentrations, and fruit quality across several pepper genotypes. The cultivars evaluated included two landraces, namely ‘JO109’ and ‘JO204’ (Capsicum annuum var. grossum), as well as the California cultivar ‘Yolo Wonder’ and the commercial F1 hybrid ‘Sammy RZ’, which served as controls. The experiment was conducted at the greenhouse facilities of the Laboratory of Vegetable Production, Agricultural University of Athens. Under reduced irrigation, most of the cultivars studied exhibited a decline in yield, which was attributed to a decrease in fruit number in ‘Yolo Wonder’ and a reduction in fruit weight in both ‘JO204’ and ‘Sammy’. In contrast, the landrace ‘JO109’ exhibited consistent yields under both growing conditions, a response likely attributed to elevated K concentration in the leaves and lower Na accumulation in the fruit, indicating enhanced tolerance to water deficit. A decline in leaf K concentration was observed in response to drought stress, while concomitantly increased concentrations of Na, Ca and Mg were recorded. Among fruit macronutrients, only Ca showed a significant decrease under reduced irrigation. Furthermore, fruit firmness (FF), titratable acidity (TA) and total soluble solids content (TSSC) exhibited higher levels under drought stress, particularly in ‘JO109’, while TA remained unaltered. These findings highlight the potential of landraces such as ‘JO109’ to be utilized in breeding programs aimed at enhancing resilience, while maintaining pepper fruit quality under limited water availability.

Nutrient intake is vital for human health, yet micronutrient deficiencies remain widespread despite sufficient calorie consumption. Biofortification is the process by which the nutrient density of food crops is increased through various strategies without altering key agronomic characteristics. This approach is widely recognised as a cost-effective method for addressing micronutrient malnutrition. When combined with the nutritional properties and inherent resilience of underutilised crops to harsh conditions, biofortification emerges as highly promising and sustainable solution. This study investigates the effects of selenium biofortification by adding different doses of SeO₂ (0, 1, 2, and 4 μM) in the nutrient solution in three underutilised leafy vegetables [Portulaca oleracea L. (purslane), Taraxacum officinale L. (dandelion), and Mesembryanthemum crystallinum L. (iceplant)] grown in an open soilless system. The addition of SeO₂ to the nutrient solution increased yield in all three species, although iceplant exhibited reduced yield at the highest SeO₂ dose. In particular, the total yield of purslane was enhanced by 14–19% when treated with 1, 2, and 4 doses of SeO₂, whilst the dandelion yield increased by 25% under 4 μM SeO₂. Furthermore, the yield of iceplant increased by 14.7–17.8% at 1 and 2 μM SeO₂. SeO₂ application led to a dose-dependent increase in selenium concentration in the shoot tissues while remaining within safe intake limits. More specifically, selenium concentration in purslane, dandelion, and iceplant tissues increased by 92%, 91%, and 89%, respectively, at the highest SeO₂ dose (4 μΜ) compared to untreated plants. Selenium treatment also influenced the nutritional profile of the examined plant species. With regard to the antioxidant activity, the highest recorded value was observed at 1 μM SeO₂ for purslane and iceplant, and at 4 μM SeO₂ for dandelion. These values were enhanced by 20%, 12%, and 27%, respectively, in comparison with 0 μM SeO₂. In conclusion, rootzone SeO₂ supplementation via a nutrient solution can be considered an effective biofortification strategy that enhances growth characteristics and antioxidant properties of the three investigated underutilised leafy vegetables without compromising their nutritional value.

This study examined the effects of both nitrogen (N) rate and form on the growth, nutrient uptake, and quality parameters of hydroponically grown purslane (Portulaca oleracea L.) during a spring cultivation cycle. Purslane was cultivated in a floating hydroponic system under either adequate or limiting N conditions. More specifically, under adequate N conditions, plants were supplied with NS where ammonium nitrogen (NH₄-N) accounted for either 7% (Nr7) or 14% (Nr14) of the total-N. The limiting N conditions were achieved through the application of either an NS where 30% of N inputs were compensated with Cl (N30), or an NS where 50% of N inputs were balanced by elevating Cl and S by 30% and 20%, respectively (N50). The results demonstrated that mild N stress enhanced the quality characteristics of purslane without significant yield losses. However, further and more severe N restrictions in the NS resulted in significant yield losses without improving product quality. The highest yield reduction (20%) occurred under high NH₄-N supply (Nr14), compared to Nr7-treated plants, which was strongly associated with impaired N assimilation and reduced biomass production. Both N-limiting treatments (N30 and N50) effectively reduced nitrate accumulation in edible tissues by 10% compared to plants grown under adequate N supply (Nr7 and Nr14); however, nitrate levels remained relatively high across all treatments, even though the environmental conditions of the experiment favored nitrate reduction. All applied N regimes and compensation strategies improved the antioxidant and flavonoid content, with the highest antioxidant activity observed in plants grown under high NH₄-N application, indirectly revealing the susceptibility of purslane to NH₄-N-rich conditions. Overall, the form and rate of N supply significantly influenced both plant performance and biochemical quality. Partial replacement of N with Cl (N30) emerged as the most promising strategy, benefiting quality traits and effectively reducing nitrate content without significantly compromising yield.

The increasing threat of salinity, exacerbated by climate change and unsustainable agricultural practices, necessitates innovative and sustainable crop management strategies to safeguard vegetable crop production and global food security. This review highlights a comprehensive framework that combines physiological insights with practical interventions aimed at enhancing salinity tolerance in vegetable crops. Key strategies include grafting, precision irrigation and fertilization, biofortification, and biostimulant application. These practices are applicable to both soil-based and soilless cultivation systems, offering broad relevance across diverse production environments. Combining and adapting these strategies to specific crops and environments is essential for developing sustainable, productive vegetable farming systems that can survive rising salinity and secure future food supplies. Future research focus on optimizing these integrated methods and elucidating their underlying mechanisms to enable wider and more effective adoption.