The Effect of Salinity on Fruit Quality and Yield of Cherry Tomatoes

Hydroponic cultivation of vegetables avoids problems with soil-borne plant pathogens and may allow higher yield. In arid climates and particularly on islands, high concentrations of sodium chloride can be present in the groundwater. For instance, in many sites of Malta, the groundwater contains more than 10 mM sodium chloride. Here we investigated the effects of sodium chloride at levels typically found in Malta on yield, physiology and fruit quality of tomato, the economically most important vegetable. We selected cherry tomatoes since their production is attractive due to their high marketing value. While the yield declined at higher salinity levels tested (17 and 34 mM), the quality increased significantly as indicated by higher total soluble solids and fructose and glucose levels. The type of substrate—coco peat, perlite or Rockwool—had only minor effects. Although the concentration of citric acid and malic acid remained unaffected, the pH dropped by approximately 0.1 unit and the titratable acidity increased slightly. This might be explained by a high uptake of chloride but a lower increase of the sodium content and a reduced potassium level in the fruits, shifting the equilibrium of the organic acids more to their protonated forms. Proline increased significantly, while the level of glutamic acid, which is crucial for the taste, remained unchanged. Our results show that cherry tomatoes can be cultivated in nutrient solutions prepared with salt-containing groundwater, as found in Malta. The yield declined to some extent but the quality of the produced fruits was higher compared to cultivation in salt-free media.

Preparation and Characterization of Chitosan–Nano-ZnO Composite Films for Preservation of Cherry Tomatoes

Chitosan is widely used as a natural preservative of fruits and vegetables, but its poor mechanical and water resistances have limited its application. Therefore, in this study, we prepared chitosan composite films by incorporating different amounts of nano-zinc oxide (nano-ZnO) to improve the mechanical properties of chitosan. We also assessed the antibacterial activity of these films against selected microorganisms. The addition of nano-ZnO improved the tensile strength (TS) and elongation at break (EAB) of the chitosan films and reduced their light transmittance. TS and EAB increased from 44.64 ± 1.49 MPa and 5.09 ± 0.38% for pure chitosan film to 46.79 ± 1.65 MPa and 12.26 ± 0.41% for a 0.6% nano-ZnO composite film, respectively. The ultraviolet light transmittance of composite films containing 0.2%, 0.4%, and 0.6% nano-ZnO at 600 nm decreased from 88.2% to 86.0%, 82.7%, and 81.8%, respectively. A disc diffusion test showed that the composite film containing 0.6% nano-ZnO had the strongest antibacterial activity against Alicyclobacillus acidoterrestris, Staphylococcus aureus, Escherichia coli, and Salmonella. In a 15-day preservation study, chitosan composite films containing 0.6% nano-ZnO maintained the soluble solid content of cherry tomatoes, effectively inhibited their respiration, and exhibited good antibacterial properties against the selected microorganisms. Overall, the prepared chitosan nano-ZnO composite film showed a good preservation effect on cherry tomatoes.

Comparative Genome Analysis of Genes Regulating Compound Inflorescences in Tomato

Inflorescences are the main factor affecting fruit yield. The quantity and quality of inflorescences are closely related to fruit quality and yield. The presence of compound inflorescences in cherry tomatoes is well established, and it has been discovered by chance that compound racemes also exist in tomatoes. To explore the formation of compound inflorescences in tomato, transcriptome sequencing was performed on Moneymaker (MM) and Compound Inflorescence (CI) plants. In-florescences were collected in three periods (early, middle and late) in three replicates, for a total of 18 samples. Data analysis showed that the DEGs were most enriched in metabolic pathways and plant hormone signal transduction pathways. The DEGs were also enriched in the cell cycle pathway, photosynthesis pathway, carbon metabolism pathway and circadian rhythm pathway. We found that the FALSIFLORA (FA), COMPOUND INFLORESCENCE (S) and ANANTHA (AN) genes were involved in compound inflorescence development, not only revealing novel genes but also providing a rich theoretical basis for compound inflorescence development.

Physiological changes in green and red cherry tomatoes after photocatalytic ethylene degradation using continuous air flux

In this work photocatalytic ethylene degradation (TiO2-UV) was applied in green cherry tomatoes with the aim to control biochemical and physiological changes during ripening. Photocatalytic process was performed at 18 °C ± 2 °C and 85% HR for 10 days using continuous air flux. Ethylene, O2 and CO2 concentration from cherry tomatoes under TiO2-UV and control (c) fruits, were measured by GC-MS for 10 days. After that, the tomatoes were stored for 20 days. During the photocatalysis process, ethylene was completely degraded and control fruits, the ethylene was 28.73 nL g−1. Respiration rate was lower for fruits under TiO2-UV than control. During storage period, cherry tomatoes treated by TiO2-UV, showed lower ethylene concentration, respiration rate, total soluble solid, lycopene, sugar and organic acid content than control showing that the fruits treated with photocatalysis did not reach the full maturity. In addition, all the cherry tomatoes showed different maturity stages. Fungal incidence was higher in control fruits than fruits treated with photocatalysis. This research showed for the first time that photocatalytic technology preserved the physiological quality of cherry tomatoes for 30 days of storage, being a promised technology to preserve cherries tomatoes.

Physicochemical Characteristics and Bioactive Compounds of New Black Cherry Tomato (Solanum lycopersicum) Varieties Grown in Vietnam

Some physicochemical characteristics and bioactive compounds of three varieties of black cherry tomato (Indigo Rose, OG, F1:001) grown in Vietnam were investigated. The results showed that the two varieties OG and F1:001 have roughly the same size with weight, height, diameter, geometric diameter and surface area ranging from 21.62 to 22.25 g, 25.69 to 26.40 mm, 24.46 to 25.11 mm, 24.86 to 25.53 mm and 19.47 to 20.51 cm2, respectively. Meanwhile, the Indigo variety is twice as large with the corresponding parameters as 45.2 g, 48.03 mm, 55.18 mm, 52.69 mm and 87.20 cm2. All three varieties are in a spherical shape with sphericity and aspect ratios ranging from 96.72 to 109.69% and 0.951 to 1.149, respectively. The variety of OG contained higher levels of bioactive compounds, especially anthocyanin, not only in the skin but also in the outer tissue. Six anthocyanin compounds were identified in the two varieties of OG and Indigo Rose while only four anthocyanin compounds were found in the variety of F1:001. Among them, two new compounds (delphinidin-3-(p-coumaroyl)-glucoside and delphinidin-3-(p-coumaroyl)-glucoside-arabinoside) were discovered in all three varieties. The finding of this study will be a basis for consumers to better understand the nutritious properties of black cherry tomatoes grown in Vietnam, thereby promoting the need to grow and consume this beneficial fruit. The study also provides the important physicochemical parameters of black cherry tomatoes, which are the initial basis for fruit preservation and processing.