The effects of soilless substrate-based versus soil cultivation on overall fruit quality and yield in tomato (Solanum lycopersicum) were studied using the tomato cv. Zhonghua Lvbao. Experiments for tomato soilless cultivation were carried out under greenhouse conditions. Plant growth, fruit quality and yield, and physiologic traits were observed. RNA-seq and RT-PCR, as well as metabolomic analyses were performed to examine the expressed genes and metabolites under soilless substrate cultivation. The results showed that the plant height, stem diameter, and chlorophyll contents of tomato under substrate-based cultivation were increased by 37.3%, 19.8%, and 15.3%, respectively, compared with soil cultivation system. Leaf photosynthetic and transpiration rates, stomatal conductance, and root vitality of tomato, under substrate-based cultivation, increased by 29.0%, 21.2%, 43.9%, and 84.5%, respectively, compared with soil cultivation. The yield reached 7177.5 kg/667 m², and the relative yield increased by 10.1%, compared with soil cultivation. The contents of total soluble sugar, soluble solids, and vitamin C increased by 35.7%, 19.7%, and 18.2%, respectively, higher than those of soil cultivation in tomato fruits, while nitrate content and titratable acid decreased by 29.4% and 11.8%, respectively. Therefore, substrate-based-cultivation can increase production and improve tomato fruit quality and taste. We examined the expressed genes and metabolites to explore the molecular mechanism of plant growth and overall fruit quality improvement in substrate-based cultivation. A total of 476 differentially expressed genes were identified by transcriptomes profiling, of which 321 and 155 were significantly up- and down-regulated, respectively. The results of metabolomics analysis showed that 441 metabolites were detected, where 24 and 36 metabolites were up- and down-regulated, respectively. By combining analyses of transcriptomic and metabolic groups, genes and metabolites related to the fruit quality were mainly concentrated in the vitamin B6/ascorbic acid/aldonic acidmetabolism, and glycerophospholipid metabolic pathways. Therefore, substrate-based cultivation can elevate vitamin and soluble sugar contents and the expression of fruit flavor related genes, which lays an initial background for exploring the mechanism of substrate-based cultivation, in order to improve the quality of tomato in the future.

Introduction: Excessive nitrate accumulation in leafy vegetables poses health risks and indicates inefficient nitrogen use in conventional agriculture. While nitrogen metabolism has been extensively studied, the molecular mechanisms linking nutrient deprivation to nitrate reduction in vegetables remain unclear.Methods: In this study, we investigated these mechanisms in lettuce (Lactuca sativa var. ramosa Hort.) by analyzing nitrate content and gene expression in leaves and roots under nutrient deprivation.Results: After five days of treatment, nitrate content decreased by 57.49% in leaves and 50.77% in roots. Transcriptome sequencing identified 323 and 3,494 differentially expressed genes (DEGs) in leaves and roots, respectively, with 78 shared DEGs. KEGG enrichment analysis revealed involvement of DEGs in pyrimidine metabolism, base excision repair, hormone signaling, terpenoid biosynthesis, and triglyceride metabolism, indicating cross-talk between nitrate regulation and stress responses. Nitrate transporter genes NRT2.4 and NRT2.5 were upregulated in roots, while NRT1 was induced in leaves, suggesting enhanced nitrate redistribution. Additionally, antioxidant genes such as POD, LOX, and cytochrome P450 were upregulated in roots, whereas SODC was downregulated in both tissues. These results suggest that lettuce responds to nutrient deprivation by activating nitrate transport and antioxidant pathways to reduce nitrate levels and enhance nitrogen use efficiency.Discussion: This study provides a foundation for optimizing pre-harvest strategies to improve lettuce quality and identifies candidate genes (e.g., NRT2.5, LOX) for breeding low-nitrate varieties suited for nitrogen-limited environments.

Grafting is an effective horticultural technique that can significantly enhance the disease resistance and stress resistance of watermelon. This review summarizes the types of rootstocks used in watermelon grafting and investigates the responses of graft-cucurbits to viral/fungal pathogens, root-knot nematodes, and stresses (such as drought, temperature, and salinity). The reviews also summarize the changes in fruit quality and underlying mechanisms induced by graft resistance. With recent research advances summarizing and analyzing, this review will provide valuable insight and reference for promoting resistance improvement and sustainable production in cucurbit and other vegetable crops by grafting. In summary, grafting can effectively improve the stress resistance and yield of watermelon, but optimizing fruit quality is still the focus of future research.

To investigate the effects of regulated deficit irrigation (RDI) on tomato fruit quality and flavor, a study was conducted using the tomato cultivar 'Gaotang No. 1' under three irrigation treatments: CK (conventional irrigation, 16 m³/mu per session), T1 (50% reduction, 8 m³/mu), and T2 (25% reduction, 12 m³/mu). The impact on plant growth, yield, fruit quality, and volatile organic compounds (VOCs) was evaluated. Results showed that the T2 treatment significantly reduced yield (−26.55%) but enhanced fruit firmness (35.57% increase in shoulder hardness), soluble solids (14.56%), vitamin C content (44.19%), and the sugar-to-acid ratio (2.25%). Volatile analysis revealed that T2 markedly increased the concentration of key aroma compounds with odor activity values (OAV) >10, including 2-pentyl furan (24.71%), (Z)-3,7-dimethyl-1,3,6-octadecatriene (128.49%) contributing to floral aroma, 2-ethyl-5-methylpyrazine (204.10%) associated with fruity aroma, and 4- isopropyltoluene (125.79%) contributing to citrus aroma. These compounds significantly shaped the overall aroma profile, resulting in a richer flavor. The findings confirm that moderate RDI (25% reduction) effectively balances yield and fruit quality by improving texture, nutritional value, and aroma complexity, offering a promising strategy for water-efficient, quality-focused tomato production.