Search

Featured Application: The results of the present work provide useful insights into the response of Diplotaxis tenuifolia L. plants to salinity stress and biostimulant application under successive crop cycles. Considering the complex effects of biostimulants on vegetable crops, providing new information regarding the positive effects of this agronomic practice under salinity stress and variable growing conditions will be useful for farmers and crop production stakeholders in their efforts to address the increasing soil salinization and degradation of the quality of irrigation water. The availability of irrigation water of good quality is decreasing due to soil salinization and the deterioration of aquifers. Moreover, ongoing climate change severely affects crop production and necessitates the intensification of cropping systems in order to ensure food security at a global scale. For this purpose, the aim of the present study was to evaluate the mitigating effects of two natural biostimulants on Diplotaxis tenuifolia L. plants cultivated at different salinity levels (EC of 0 dS m−1, 2 dS m−1, 4 dS m−1, and 6 dS m−1) and harvested at six consecutive cropping cycles. The tested factors showed a varied combinatorial effect on the tested parameters. These findings indicate the importance of considering growing conditions and cropping periods when applying biostimulants in D. tenuifolia plants under salinity stress. Antioxidant activity and bioactive compounds, such as total phenols, carotenoids, and total ascorbic acid, were variably affected by salinity, biostimulant application, and harvesting time, while mineral profile was also affected by the tested factors depending on the combination of factors. Finally, nitrate content showed decreasing trends with increasing salinity, while biostimulant application resulted in the higher accumulation of nitrates compared to the untreated plants. Although biostimulant application seems to alleviate the negative effects of salinity stress, the effect of growing conditions, as indicated by successive crop cycles, is also important for the response of D. tenuifolia plants to saline conditions and biostimulant application.

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.

During the last few decades, the food and beverage industry faced increasing demand for the design of new functional food products free of synthetic compounds and artificial additives. Anthocyanins are widely used as natural colorants in various food products to replenish blue color losses during processing and to add blue color to colorless products, while other compounds such as carotenoids and betalains are considered as good sources of other shades. Root vegetables are well known for their broad palette of colors, and some species, such as black carrot and beet root, are already widely used as sources of natural colorants in the food and drug industry. Ongoing research aims at identifying alternative vegetable sources with diverse functional and structural features imparting beneficial effects onto human health. The current review provides a systematic description of colored root vegetables based on their belowground edible parts, and it highlights species and/or cultivars that present atypical colors, especially those containing pigment compounds responsible for hues of blue color. Finally, the main health effects and antioxidant properties associated with the presence of coloring compounds are presented, as well as the effects that processing treatments may have on chemical composition and coloring compounds in particular.

Space farming for fresh food production is essential for sustaining long-duration space missions and supporting human life in space colonies. However, several obstacles need to be overcome including abnormal light conditions and energy limitations in maintaining Bioregenerative Life Support Systems (BLSSs). The aim of the present study was to evaluate six lettuce cultivars (baby Romaine, green Salanova, Lollo verde, Lollo rossa, red oak leaf and red Salanova) of different types and pigmentations under optimal and suboptimal light intensity and to identify the most promising candidates for BLSSs. Baby Romaine performed better than the rest of the tested cultivars under suboptimal light intensity, demonstrating a more efficient light-harvesting mechanism. Stomatal resistance increased under suboptimal light conditions, especially in the case of Lollo verde and red oak leaf cultivars, indicating stress conditions, whereas intrinsic water-use efficiency was the highest in baby Romaine and red oak leaf cultivars regardless of light regime. Nitrate content increased under suboptimal light intensity, especially in the cultivars green Salanova and Lollo verde, while P and Ca accumulation trends were also observed in baby Romaine and Lollo verde cultivars, respectively. Chicoric acid was the major detected phenolic acid in the hydroxycinnamic derivatives sub-class, followed by chlorogenic, caffeoyl-tartaric and caffeoyl-meso-tartaric acids. Chicoric and total hydroxycinnamic acids were not affected by light intensity, whereas the rest of the detected phenolic compounds showed a varied response to light intensity. Regarding cultivar response, red oak leaf exhibited the highest content in chicoric acid and total hydroxycinnamic acids content under suboptimal light intensity, whereas red Salanova exhibited the highest hydroxycinnamic derivatives profile under optimal light conditions. The main detected carotenoids were β-cryptoxanthin and violaxanthin+neoxanthin, followed by lutein and β-carotene. All the target carotenoids decreased significantly under low light intensity, while red Salanova maintained a distinct carotenoids profile. Overall, cultivation of assorted lettuce cultivars is the optimal scenario for space farming, where baby Romaine could provide adequate amounts of fresh biomass owing to its high light-use efficiency while red oak leaf and red Salanova could contribute to the daily dietary requirements for health-promoting bioactive compounds such as polyphenols and carotenoids.

The effect of cultivar and nutrient solution macrocation proportions (SK, SCa, SMg) on the bioactive content of hydroponically cultivated lettuce was evaluated on two lettuce cultivars (red and green-pigmented Salanova®) grown in a fully controlled Fitotron® chamber. Fresh weight and color attributes were superior in green Salanova and in SK-treated plants, while elevated macrocation proportions (SK, SCa, and SMg) affected the corresponding minerals, P and Na content. SCa and SMg treatments raised ascorbate concentration and reduced nitrate levels in treated plants. Chicoric and chlorogenic acids were higher in red over green Salanova. Chlorogenic acid was higher in SCa and SMg plants and chicoric acid levels were SMg > SCa > SK. The SMg-treated red Salanova contained higher concentrations of target carotenoids. In conclusion, nutrient solution management constitutes an effective cultural practice to increase bioactive properties and functional quality of hydroponically grown lettuce.