Fertilization influences the soil microbiome. However, little is known about the effects of long-term fertilization on soil microbial metabolic pathways. In this study, we investigated the soil microbiome composition and function and microbial participation in the N cycle according to the Kyoto Encyclopedia of Genes and Genomes (KEGG) and gene ontology (GO) functional annotation of different genes in a metagenomic analysis after long-term fertilization. Fertilizer application significantly changed the soil C/N ratio. Chemical fertilizer (NPK) treatment decreased soil pH, and chemical fertilizer combined with straw (NPK+S0.5) treatment increased ammonium nitrogen (NH₄⁺-N) but decreased nitrate nitrogen (NO₃⁻-N). NPK, NPK+S0.5 and S0.5 applications did not change the soil microbiome composition or dominant phylum but changed the relative abundances of microbiome components. Moreover, fertilizer significantly influenced metabolic processes, cellular processes and single-organism processes. Compared with a no-fertilizer treatment (CK), the NPK treatment resulted in more differentially expressed gene (DEG) pathways than the NPK+S0.5 and S0.5 treatments, and these pathways significantly correlated with soil nitrate nitrogen (NO₃⁻-N), available phosphorus (AP) and the moisture content of soil (MC). KEGG analysis found that fertilizer application mainly affected the ribosome, photosynthesis and oxidative phosphorylation pathways. S0.5 and NPK+S0.5 increased microbial nitrogen fixation, and NPK and NPK+S0.5 decreased amoA and amoB and accelerated denitrification. Thus, organic fertilizer increased N fixation and nitrification, and inorganic N fertilizer accelerated denitrification. We found that the function of the soil microbiome under different fertilizer applications could be important for the rational application of fertilizer and for environmental and sustainable development.

Soil improvement methods can result in changes in the microbial community in blueberry soil. Bacterial communities play an important role in soil fertilizer and plant nutrient acquisition. In this study, the response of microbial community composition, microbial function, and the nitrogen (N) cycle to different improvement methods was analyzed using high-throughput sequencing to investigate the best soil improvement method from a microbial perspective. The results showed that the highest microbial diversity was observed in the treatment involving peat combined with mushroom bran (T2), followed by the peat combined with acidified rice husk (T2) both in the rhizosphere and roots. The dominant phyla were Proteobacteria and Actinobacteria both in the blueberry rhizosphere soil and roots. Interestingly, Acidobacterium and Paludibaculum, belonging to the Acidobacteria phylum, exhibited the most significant influence and were most predominant in the T2 treatment rhizosphere soil. The T2 treatment promoted the growth of N fixation functional bacteria both in the rhizosphere soil and roots. At the module level, the T2 treatment enhanced N fixation and suppressed the assimilatory and dissimilatory nitrate reduction reactions, denitrification, and nitrification in the blueberry rhizosphere. Additionally, the T2 treatment increased the abundance of root endophytic microbes involved in N fixation. Overall, our findings suggest that the addition of peat combined with acidified rice husk is the optimal soil improvement method for blueberry cultivation.

These days, one of the main issues preventing agricultural development is salinized soils. Potassium fulvic acid (PFA) not only regulates plant growth, but also improves the soil nutrient content and physical structure, which makes it a soil conditioner worth promoting. Nevertheless, the research conducted thus far on the subject of PFA with regard to plant growth and inter-root microbial communities remains somewhat limited in scope. In this study, a pot experiment was conducted to simulate both the normal environment and salt stress environment. The objective of this experiment was to verify the effect of PFA on the growth of blueberry (Vaccinium corymbosum L.) as well as its effect on the soil physical and chemical indices and the soil microbial community structure. The findings demonstrated that the implementation of potassium fulvic acids exhibited a minimal impact on the growth of blueberry plants under standard environmental conditions. However, it was observed to exert a substantial effect on enhancing various physiological parameters, including plant height, root activity, and chlorophyll synthesis, particularly in response to salt stress. PFA led to a substantial augmentation in the soil organic matter content, alongside a notable rise in the alkali-hydrolyzable nitrogen (AN) and available potassium (AK) content. Concurrently, PFA caused a notable escalation in the activities of soil urease, sucrase, acid phosphatase, and catalase (p < 0.05) in the salt-stressed environment. PFA increased the abundance of Acidobacteria, Myxococcota, Ascomycota, and Fungi_phy_Incertae_sedis under salt stress, which was mainly related to the decrease in electrical conductivity (EC) values and increase in soil acid phosphatase (S-ACP) activity. It is evident that the implementation of PFA is advantageous in enhancing the saline environment, mitigating the impact of salt damage on blueberries and establishing a foundation for the expansion of cultivated areas and the sustainable cultivation of blueberries.

Blueberries are highly prone to postharvest decay, resulting in significant nutrient loss and economic damage. Current research on the postharvest storage of blueberries primarily focuses on storage techniques, while the underlying mechanisms remain insufficiently explored. To further explore the role of exogenous melatonin (MT) in delaying the senescence of blueberry fruit, this study treated fruits with sterile water (control) and 300 μmol·L⁻¹ MT during the pink fruit stage. After maturation, the fruits were stored at 4 °C for 30 days, and we investigated the effects of exogenous MT on postharvest blueberry quality, reactive oxygen species (ROS) metabolism, antioxidant enzyme activities, and the expression of related genes. The results showed that, compared to the control, 300 μmol·L⁻¹ MT effectively delayed the increase in fruit decay rate and the decline in firmness, while enhancing the total soluble solids (TSS) content and ascorbic acid (AsA) levels. It also reduced the accumulation of malondialdehyde (MDA), hydrogen peroxide (H₂O₂), and the production rate of superoxide anion (O₂⁻), while maintaining higher activities of ascorbate peroxidase (APX), superoxide dismutase (SOD), and catalase (CAT). Furthermore, MT treatment upregulated the expression of antioxidant enzyme-related genes VcSOD1, VcSOD2, and VcAPX3. These findings indicate that treating blueberries with 300 μmol·L⁻¹ MT at the pink fruit stage improves postharvest quality, alleviates oxidative damage, and delays senescence. This study provides a theoretical foundation and practical reference for blueberry storage and preservation, laying the groundwork for further understanding the regulatory mechanisms of exogenous MT in postharvest fruit senescence.

Due to its thin, juicy skin and high physiological activity, blueberries are easily susceptible to damage by pathogenic bacteria during storage and transportation after harvest. However, there are relatively few studies on the mechanisms by which blueberries resist rot disease. Therefore, in this study, the blueberry cultivar ‘Northland’ was used as the experimental material. Using a combination of single spore isolation, morphological analysis, and molecular biology methods, the types of pathogenic bacteria responsible for postharvest decay of blueberries were investigated, as well as the mechanisms by which EBR influences disease resistance and quality control. The results indicated that the pathogen responsible for blueberry fruit rot was Talaromyces amestolkiae , and treatment with 2,4-epibrassinolide (EBR) could significantly reduce both the fruit rot rate and the disease index. Among the treatments, 0.4 mg/L EBR showed the most pronounced effect, effectively maintaining fruit firmness, titratable acidity, and soluble solids content, while reducing weight loss, decreasing the extent of membrane lipid peroxidation, and enhancing the activities of antioxidant enzymes such as superoxide dismutase (SOD) and peroxidase (POD) by 251.46% and 208.18%, respectively. Additionally, the activity of pathogenesis-related proteins, including chitinase, increased, and the stability of antioxidants, such as total phenols, was preserved. EBR improved the disease resistance of blueberry fruit through multi-pathway synergy and delayed the deterioration of postharvest quality. The findings of this study can offer theoretical support for the eco-friendly prevention and management of postharvest diseases in blueberries.

The degree of soil salinization is still on the rise. In saline environments, NaCl is the main substance that causes plant salt damage, with the toxicity of ions under salt stress primarily involving sodium (Na⁺) or chloride (Cl⁻). However, fewer studies have focused on Cl⁻ stress. This study investigated the differences in the growth and physiology of five blueberry varieties under Cl⁻ stress, aiming to understand the mechanisms of Cl⁻ tolerance and the physiological responses to Cl⁻ stress in these varieties. Five blueberry varieties (‘Northland’, ‘PL19’, ‘Duke’, ‘Reka’, and ‘Bonnie’) were used as test materials. This study examined the changes in growth and physiological indices of blueberry plants under different concentrations of Cl⁻ (A1–A6: 50, 100, 150, 200, 250, and 300 mmol/L) treatments. A control treatment (CK) was included to serve as a baseline for comparison. We comprehensively evaluated the Cl⁻ tolerance of these five varieties to screen for chlorine-tolerant varieties. This study examined the concentration-dependent changes in growth and physiological indices of blueberry plants, including plant height, leaf area, chlorophyll content, electrical conductivity, levels of soluble sugar (SS), malondialdehyde (MDA), proline (Pro), and soluble protein (SP), as well as the activities of superoxide dismutase (SOD) and catalase (CAT). The results revealed that as the Cl⁻ concentration increased, the growth of all blueberry varieties was inhibited; plant height, leaf area, and chlorophyll content consistently declined, whereas electrical conductivity showed a steady increase. SS and MDA content exhibited a biphasic response, with an increase at lower Cl⁻ concentrations followed by a decrease at higher concentrations. The activities of SOD and CAT in ‘Duke’ consistently increased with rising Cl⁻ levels. In ‘PL19’ and ‘Reka’, chlorophyll content decreased with increasing Cl⁻, while their proline content rose initially and then declined. In contrast, the other varieties generally showed an increasing trend in proline content. Similarly, the soluble protein content of ‘Northland’ and ‘PL19’ increased at lower Cl⁻ levels and decreased at higher concentrations, whereas ‘Bonnie’, ‘Duke’, and ‘Reka’ displayed an overall declining trend. Principal component analysis indicated that the Cl⁻ tolerance of the blueberry varieties ranked as follows: ‘Duke’ > ‘Bonnie’ > ‘Reka’ > ‘PL19’ > ‘Northland’. These findings lay a foundation for blueberry cultivation in saline–alkaline soils and support the selection and development of new, chlorine-tolerant varieties.