This study investigated the effect of preharvest treatment of 0.25 mM methyl jasmonate (MeJA) and 0.5 mM salicylic acid (SA) on quality parameters, most important secondary metabolites (lycopene, β-carotene, ascorbic acid, total phenolics, and flavonoids), antioxidant activities, and amino acid contents of ‘Kumato’ tomato. Treatments with MeJA and SA led to an increase of total yield per plant and were effective in maintaining the fruit quality attributes such as firmness, total soluble solids, titratable acidity, and Brix acid ratio at two maturity stages (S1 and S2). In addition, lycopene, β-carotene, ascorbic acid, total phenolics, and flavonoids were significantly higher in the treated fruit than in the control. Moreover, γ-aminobutyric acid (GABA), essential amino acids, and antioxidant activity increased due to MeJA and SA treatments at both stages, especially with MeJA treatment at S2. Overall results also showed the effectiveness of MeJA treatment than SA on improving the yield and nutritional quality of ‘Kumato’ tomato.

Tomatoes are rich in secondary metabolites such as lycopene, β-carotene, phenolics, flavonoids, and vitamin C, which are responsible for their antioxidant activates. A high level of γ-Aminobutyric acid (GABA), a health-promoting functional compound, was also found to accumulate in tomato fruit. In addition to the internal quality attributes, the acceptance of the tomato fruit by consumers is highly dependent on appearance and taste. Hence, we conducted this study to evaluate ‘Tori’, ‘TY VIP’, ‘Mamirio’, and ‘Arya’ tomato cultivars based on their physicochemical characteristics, contents of secondary metabolites, and GABA content. The results have revealed that the tested cultivars were very firm, which renders them the best choice for postharvest distribution of fresh market tomatoes as they resist impacts during harvesting and postharvest operations. Based on total soluble solids (TSS), titratable acidity (TA), and Brix acid ratio (BAR) the choice of cultivar could be ‘Mamirio’ > ’Tori’ > ‘TY VIP’ > ‘Arya’. Apart from flavor intensity, ‘Mamirio’ and ’Tori’ also revealed the highest content of ascorbic acid while ‘Mamirio’ and ‘Arya’ had the highest carotenoids (lycopene and β-carotene) accumulation. On the other hand, the highest total phenolics content was recorded from ‘TY VIP’ and ‘Arya’. Moreover, the highest total flavonoids and GABA contents were recorded from ‘TY VIP’. Nevertheless, the antioxidant activity of ‘TY VIP’ was the lowest of all tested cultivars while the highest was recorded from ‘Mamirio’. Taken together, the findings of the present study could suggest that the consumers’ requirements could be better fulfilled by choosing cultivars for the specific target functional compounds. From the tested cultivars, if the target is ascorbic acid, carotenoids, and antioxidant activity then ‘Mamirio’ is the best choice. On the other hand, if the target is total phenolics, flavonoids, and GABA then ‘TY VIP’ is the best choice. One could also label ‘Mamirio’ as an ‘antioxidant tomato’ and ‘TY VIP’ as the ‘GABA tomato’.

Vertical hydroponics farming has emerged as an alternative solution to feed the continuously growing world population. Additionally, recent studies reported that the exogenous treatments of jasmonic acid influence the phytochemical composition of Brassicaceae. We conducted this study to determine the effect of preharvest methyl jasmonate (MeJA) treatment on the phytochemical composition and antioxidant activities of soil- and hydroponically grown pak choi. An aqueous solution of 0.5-mM MeJA was sprayed to saturation on the aerial plant part three days before harvest. The harvested pak choi was freeze-dried and then powdered to measure the antioxidant activity and the contents of chlorophylls (Chls), total phenolics and flavonoids, and glucosinolates (GSLs). The overall results revealed that pak choi grown in vertical hydroponics had higher total Chls and total phenolics than those grown in soil in the greenhouse, regardless of MeJA treatment. Nevertheless, the GSLs content and total flavonoids increased significantly due to MeJA treatment in both growing systems, and the highest values were recorded in hydroponically grown MeJA-treated pak choi. Similarly, the 2, 2-di-phenyl-1-picrylhydrazyl (DPPH) radical scavenging capacity, Trolox-equivalent antioxidant capacity (ABTS), oxygen radical absorbance capacity (ORAC), and ferric-reducing antioxidant power (FRAP) were highest in hydroponically grown MeJA-treated pak choi. Taken together, the preharvest foliar treatment of MeJA can be used to improve the phytochemical composition of pak choi grown in both growing systems. Interestingly, the results strongly support the use of MeJA treatment in the vertical hydroponics growing system compared to the conventional growing system in the soil. This indicates that supplementing the vertical hydroponic growing system with preharvest MeJA treatment could be the best option to improve both the yield per square meter and the quality of pak choi. Besides, MeJA-treated pak choi could be used as a value-added horticultural commodity, as its antioxidant activity increased after treatment. Moreover, after further studies, MeJA could also be applied to other Brassica vegetables to improve their GSL contents and antioxidant properties.

Growing microgreens on trays without substrate in a vertical multilayered growing unit offers several advantages over traditional agriculture methods. This study investigated the yield performance and nutritional quality of five selections of radish microgreens grown in sprouting trays, without a substrate using only water, in an indoor multilayer cultivation system using artificial light. Various parameters were measured, including fresh weight, dry matter, chlorophyll, minerals, amino acids, phenolics, flavonoids, anthocyanins, vitamin C, glucosinolates, and antioxidant activity with four different in vitro assays. After ten days, the biomass had increased by 6-10 times, and the dry matter varied from 4.75-7.65%. The highest yield was obtained from ‘Asia red’, while the lowest was from ‘Koregon red’. However, ‘Koregon red’ and ‘Asia red’ had the highest dry matter. ‘Asia red’ was found to have the highest levels of both Chls and vitamin C compared to the other cultivars, while ‘Koregon red’ exhibited the highest levels of total phenolics and flavonoids. Although variations in the levels of individual glucosinolates were observed, there were no significant differences in the total content of glucosinolates among the five cultivars. ‘Asia purple’ had the highest anthocyanin content, while ‘Asia green 2’ had the lowest. The K, Mg, and Na concentrations were significantly highest in ‘Asia green 2’, and the highest Ca was recorded in ‘Asia purple’. Overall, ‘Asia purple’ and ‘Koregon red’ were the best cultivars in terms of nutritional quality among the tested radish microgreens. These cultivars exhibited high levels of dry weight, total phenolics, flavonoids, anthocyanins, essential and total amino acids, and antioxidant activities. Moreover, the implementation of this vertical cultivation method for microgreens, which relies solely on water and seeds known for their tall shoots during the sprouting could hold promise as a sustainable approach. This method can effectively be utilized for cultivar screening and fulfilling the nutritional and functional needs of the population while minimizing the environmental impacts associated with traditional agriculture practices.