This study investigated how salicylic acid (SA) mediates the response of melon (Cucumis melo) seeds to salt stress using physiological and transcriptomic methods. The effects of SA on the antioxidant enzymes, osmoregulatory substances, and transcriptome of melon seeds under salt stress were investigated using sodium chloride (NaCl, 100 mmol·L⁻¹) as the stress stimulant and SA + NaCl (0.25 mmol·L⁻¹ + 100 mmol·L⁻¹) as the alleviation treatment. The results showed that SA positively influences salt tolerance by increasing the activity of superoxide dismutase activity (SOD) and catalase activity (CAT) while decreasing proline content (Pro). Differentially expressed genes (DEGs) were identified by transcriptome data analysis, of which 2958 were up-regulated, and 2157 were down-regulated. These genes were mainly involved in the mitogen-activated protein kinase (MAPK) signaling pathway and plant hormone signal transduction, lipid metabolism (linoleic and α-linolenic fatty acid metabolism), biosynthesis of secondary metabolites (phenylpropanoid pathway and flavonoid biosynthesis), and related pathways. Further analysis revealed that SA might alleviate salt stress by initiating a series of signaling pathways under salt stress, participating in lignin biosynthesis to improve cell wall stability, and positively regulating lipoxygenase (LOX) genes. These results provide valuable information and new strategies for future salt resistance cultivation and high melon yield.

Melon fruit cracking reduces yield, increases transportation costs, and shortens shelf life, which makes the development of cracking-resistant varieties crucial for the industry’s advancement. This study investigated the pathways and genes related to melon fruit cracking through cell morphology observation, endogenous hormone analyses, and transcriptome analysis of two contrasting advanced inbred lines, the extremely crack-resistant line R2 and the crack-susceptible line R6. R2 has small, tightly packed epidermal cells with a thick cuticle, while R6 has larger, more loosely arranged epidermal cells and a significantly thinner cuticle. Hormonal analysis revealed significant differences in abscisic acid, cytokinin, gibberellin, auxin, and salicylic acid contents between R2 and R6 at various fruit developmental stages. The abscisic acid and salicylic acid content in R2 were 1.9–5.2 times and 1.5–3.6 times higher than those in R6, respectively, whereas the gibberellin content in R6 was 1.5–2.3 times higher than that in R2. Pericarp transcriptome analysis identified 4281, 6242, and 6879 differentially expressed genes (DEGs) at 20, 30, and 40 days after anthesis, respectively. Among these, 47 DEGs related to phenylpropanoid biosynthesis (ko00940) and 79 DEGs involved in plant hormone signal transduction (ko04075) were differentially expressed at two or more stages. WGCNA analysis identified six core hub genes that potentially play a role in regulating melon fruit cracking. These findings lay a foundation for further studies on the functional roles of crack-resistant genes and the breeding of crack-tolerant varieties.

Tillage practices significantly influence crop yield and soil quality. This study investigated the impact of rotary tillage (RT) and deep tillage (DT) on soil properties, microbial diversity, and melon (Cucumis melo L.) root growth and yield. RT involved breaking up the topsoil to a depth of 15 cm using a rotary tiller, while DT employed a rotary tiller followed by a moldboard plow to turn the soil layer over to a depth of 35 cm. The melon variety “Nasimi” was used as the material. Our findings revealed a remarkable response of soil phosphorus to tillage practices. High-throughput sequencing results revealed a significant impact of tillage practices on the soil fungal composition, richness, and diversity but little impact on the bacterial communities. Compared to RT, DT markedly enhanced melon root length, root surface area, root volume, and mean root diameter by 47.42%, 56.70%, 58.83%, and 27.28%, respectively. Additionally, DT treatments significantly increased melon yield (53.46%) compared to RT. The results indicate that DT improves soil nutrient availability, affects soil fungal community characteristics, and optimizes root distribution in soil, thereby improving melon yield. The findings offer valuable theoretical insights for the implementation of effective tillage practices in open-field melon cultivation.

Simplified fertilization is a core technology for achieving efficient melon cultivation. However, the optimal application depth of slow-release fertilizers in the major melon-producing regions of Xinjiang remains poorly defined. In this study, field experiments were conducted to evaluate three application depths of slow-release fertilizer: 15 cm (SF15), 25 cm (SF25), and 35 cm (SF35). Conventional fertilization (CF; 20–25 cm) and a no-fertilizer treatment (F0) were included as controls to systematically investigate the effects of application depth on nutrient accumulation, yield, economic benefits and rhizosphere microbial communities of melon. The results showed that CF treatment primarily increased soil potassium content during the middle and late growth stages and promoted potassium accumulation in fruits, while enriching beneficial microbial taxa associated with carbon cycling and plant stress resistance. In contrast, the SF35 treatment significantly increased soil nitrogen and phosphorus contents and their accumulation in fruits during the same growth stages. This treatment also enriched nitrogen-cycling bacteria and phosphorus solubilizing fungus. In addition, SF35 consistently increased the ACE index of rhizosphere bacterial communities throughout the growth period and adjusted soil pH to a range more suitable for melon growth (6.07–6.62). Importantly, melon yield under SF35 were maintained at levels comparable to those under CF, while reducing labor costs and improving economic benefits. In conclusion, 35 cm is recommended as the optimal application depth of slow-release fertilizer for melon in Xinjiang. This practice enhances key functional microbial groups and soil physicochemical properties, while achieving yield and quality comparable to those of CF in a single application. The findings of this study can provide scientific support for the standardized application of simplified fertilization technology in Xinjiang melon production.