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.

Grafting is an effective horticultural technique that significantly enhances disease resistance and stress tolerance in watermelon. This review systematically summarizes the types of rootstocks used in watermelon grafting and analyzes the effects of grafting on plant responses to biotic stresses, such as viral and fungal pathogens, root-knot nematodes infections, and abiotic stresses, including drought, temperature extremes, and salinity. Furthermore, it discusses the changes in fruit quality and explores the underlying mechanisms associated with graft-induced resistance. By synthesizing recent research advances, this review aims to offer valuable insights and practical references for improving resistance and promoting sustainable production in cucurbit and other vegetable crops through grafting. As a sustainable cultivation strategy, grafting demonstrates considerable potential for enhancing watermelon resilience and yield; however, optimizing fruit quality remains a critical focus for future research.

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.

Blossom-end rot (BER) in tomatoes is a physiological disorder primarily caused by the disruption of calcium absorption and transport. This study cultivated tomatoes using a trough-based vermiculite system. Two treatments were established: a calcium-deficient nutrient solution and a calcium-deficient nutrient solution supplemented with 0.1 mg/L BR (n = 40 plants per treatment). The activities of catalase (CAT), peroxidase (POD), and superoxide dismutase (SOD), as well as the contents of malondialdehyde (MDA) and hydrogen peroxide (H₂O₂), were measured in the leaves. Calcium ion content was also determined in various plant parts. Statistical analysis of differences was performed using Duncan’s multiple range test at a significance level of p < 0.01. Concurrently, transcriptome sequencing of root, stem, and leaf tissues was conducted via high-throughput sequencing technology. The results showed that foliar application of BR under calcium deficiency significantly reduced the incidence of BER (from 26.67% to 6.67%) and effectively increased calcium ion content in leaves, stems, and roots. At the physiological level, BR treatment markedly enhanced the activities of CAT, POD, and SOD in leaves (by 105.70%, 117.12%, and 82.77%, respectively), while reducing H₂O₂ and MDA contents (by 36.90% and 16.38%, respectively). This indicates that BR alleviates membrane lipid peroxidation damage by enhancing the antioxidant defense system. Gene Ontology (GO) enrichment analysis revealed that the differentially expressed genes (DEGs) were primarily involved in biological processes, such as secondary metabolic processes, response to oxygen-containing compounds, and cell wall organization. KEGG pathway analysis further indicated significant enrichment in pathways, including phenylpropanoid biosynthesis, plant hormone signal transduction, and plant–pathogen interaction. Additionally, key genes, such as the cytochrome c oxidase (COX) gene (Solyc03g013460.1), exhibited a gradient up-regulation pattern (root > stem > leaf) in the oxidative phosphorylation pathway. In conclusion, BR likely enhances tomato tolerance to calcium deficiency stress and effectively reduces BER incidence through multiple pathways: regulating calcium absorption and distribution, activating the antioxidant system, modulating hormone signaling pathways, and enhancing energy metabolism. These findings provide a theoretical basis for the application of BR in agricultural production.

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.

Soilless cultivation has been widely used in tomato (Solanum lycopersicum) production. The objectives of this research are to evaluate the impacts of five nutrient solutions under soilless cultivation on plant growth, fruit yield and fruit quality in tomatoes. Four experiments were conducted with six treatments (five nutrient solutions plus one control) in six-cherry tomato cultivars and two big fruited tomato cultivars and 12 traits were observed and evaluated. The results showed that each of the five solutions increased plant growth and fruit yield, and improved the fruit quality. Compared to the control, the nutrient solution treatments increased 91.3% for number of fruits on base fruit cluster, 12.1% for height, and 26.3% for stem diameter in the 2017-experiment; 17.1% for vitamin C, 13.8% for soluble solids, and 20.8% for total soluble sugar content in 2018-experiment one; 28.1% for number of fruit cluster, 25.8% for fruit yield, 9.4% for number of fruit per cluster, and 13.3% for single fruit weight in 2018-experiment two; and 27.7% for vitamin C, 14.0% for soluble solids, 18.1% for total soluble sugar content, and 14.6% for fruit yield in the 2019-experiment. The solution decreased the chemical nitrate content 16.2% in the 2018-experiment and 43.7% in the 2019-experiment, and decreased the fruit cracking rate by 87%. Treatment 2 with higher nutrient component content showed the best results of the five treatments. The significant high positive correlation among the beneficial traits, fruit yield, soluble solids, total soluble sugar content, and vitamin C, and high negative correlation between each of the four traits and nitrate content were observed, indicating that soilless cultivation can increase tomato yield with higher nutritional components and decreased nitrate content. This research provides useful information for utilizing nutrient solutions supplied to tomato soilless cultivation.