Melatonin is a secondary messenger in plants that is involved in the regulation of abiotic stress responses, but it is unclear whether it enhances the adaptive capacity of blueberries to cope with salinity stress. The effects of exogenous application of melatonin (100, 200, and 300 μmol·L⁻¹) on the growth, photosynthetic characteristics, leaf anatomy, and physiological and biochemical properties of blueberry plants under mixed salt stress (90 mmol·L⁻¹: 30 mmol·L⁻¹ Na₂CO₃ + 60 mmol·L⁻¹ NaCl) were investigated. The results showed that blueberries under 90 mmol·L⁻¹ mixed salt stress had significant salt damage symptoms, with reduced blueberry biomass, reduced chlorophyll content, and photosynthesis inhibition. In contrast, melatonin-treated blueberries showed significantly reduced salt damage symptoms compared with stressed blueberry plants, with the optimum effect at 200 μmol·L⁻¹, along with increased chlorophyll content, improved photosynthetic capacity, and increased leaf thickness under stress. Melatonin treatment resulted in reduced malondialdehyde (MDA) content and relative electrolyte leakage (EL), increased K⁺ content, and decreased Na⁺ content in blueberry roots, stems and leaves, thereby reducing the toxic effects of mixed salts on blueberries. The results indicate that melatonin can mitigate the effects of mixed salt stress on blueberries and that foliar spraying of melatonin could alleviate mixed salt-induced damage to blueberries, with the optimum effect at 200 μmol·L⁻¹ treatment. This study provided a valuable basis for exploring the mechanism of exogenous melatonin action in blueberries in saline environments.

Drought stress is a significant environmental factor that can impede plant growth and ornamental quality. Hemerocallis middendorffii, a drought-tolerant garden plant, has attracted attention for its ornamental value and application prospects. To investigate the molecular mechanism of drought stress resistance of H. middendorffii, this study employed 20% polyethylene glycol (PEG) 6000 to simulate drought stress. Leaves and roots of H. middendorfii were subjected to 24 h treatment and followed by transcriptome sequencing. Analysis revealed 8796 and 3401 differentially expressed genes (DEGs) in leaves and roots. The major biological processes and key molecular pathways activated under drought stress in H. middendorffii were revealed by Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses. The focus of this analysis was on the gene expression changes within plant hormone signal transduction pathway. Additionally, drought-associated transcription factor families such as AP2/ERF, WRKY, MYB, bHLH, NAC, and bZIP were identified among DEGs. Furthermore, potential regulatory relationships of the above transcription factors (TFs) with functional genes in the abscisic acid (ABA) and jasmonic acid (JA) signalling pathways were analysed using correlation network prediction. This research establishes the groundwork for subsequent exploration of drought-responsive gene expression and regulatory patterns in H. middendorfii and provides an importance for the systematic study of its drought-resistant molecular mechanism.

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.

The swelling agent is a plant growth regulator that alters the composition and content of nutrients and volatile gases in the fruit. To identify whether grape fruit had been treated with swelling agent, the odor information and quality indexes of grape berries treated with different concentrations of swelling agent were examined by using electronic nose technology and traditional methods. The contents of soluble sugars, soluble solids, soluble proteins and vitamin C were significantly increased in N-(2-chloro-4-pyridyl)-N’-phenylurea (CPPU) treated fruit. The contents of hexanal, (E)-2-hexenal, and nonanal aldehydes decreased significantly. Similarly, the levels of phenyl ethanol, 1-octanol, ethanol, and ethyl acetate alcohols and esters also decreased noticeably. Additionally, the levels of damascenone, linalool, and geraniol ketones and terpenoids decreased. However, the contents of benzaldehyde, D-limonene, acetic acid and hexanoic acid increased. In addition, the electrical signals generated by the electronic nose (e-nose) were analyzed by linear discriminant analysis (LDA), support vector machine (SVM) and random forest (RF). The average recognition rate of SVM was 94.4%. The results showed that electronic nose technology can be used to detect whether grapes have been treated with swelling agent, and it is an economical and efficient detection method.

In order to clarify the relationship between mineral nutrients and rhizosphere microorganisms at different growth and development stages of blueberry (Vaccinium spp.), this work studied the dynamic changes in element content and microbial quantity in different parts of blueberry plants. The test material was a 12-year-old half-highbush blueberry variety (‘Beilu’). The changes in the mineral nutrient elements in leaves, branches and the soil of blueberry plants were studied at the full bloom stage (T1), green fruit stage (T2), mature stage (T3) and late mature stage (T4), and the correlations of the average contents of mineral elements in the four periods were studied. The bacterial community in the rhizosphere soil was determined and analyzed using 16S rRNA high-throughput sequencing technology. The results showed that the changes in other mineral elements in various parts of blueberry plants varied in different periods. Nitrogen (N) showed a downward trend in branches, leaves and soil, especially in leaves (p < 0.05). The N contents in T2, T3 and T4 decreased by 9.9%, 26.4% and 29.9%, respectively. The N contents in the leaves and branches showed a downward trend at different growth stages, especially in leaves. The phosphorus (P) content in leaves showed a trend of increasing first and then decreasing, while it continued to increase in branches. The content of potassium (K) in leaves changed significantly, where it increased first and then decreased. The content of calcium (Ca) in leaves decreased first and then increased, while the content of magnesium (Mg) in branches and leaves decreased first and then increased, and the relative change was significant. The contents of iron (Fe) and zinc (Zn) in leaves decreased first and then increased, while the contents of manganese (Mn) and copper (Cu) were relatively stable. Cu decreased first and then increased in leaves and soil, and it increased first and then decreased in branches. The mineral nutrients in different growth stages of blueberry showed significant correlation in leaves, branches and soil. Mn in leaves was significantly positively correlated with P, Ca, Mg, Mn, Cu and Zn in soil (p < 0.01). Nitrogen and calcium in leaves were significantly correlated with manganese and phosphorus in soil, respectively. Ca in branches was significantly positively correlated with N and K in soil and was significantly positively correlated with Zn in soil (p < 0.01). Magnesium was significantly negatively correlated with iron in soil. The bacterial community structure of the blueberry rhizosphere soil changed significantly over time (p < 0.05), and the relative abundance showed the following trend: T4 > T2 > T3 > T1. At the phylum level, Proteobacteria, Acidobacteria, Actinobacteria, Chloroflexi and Verrucomicrobia were the dominant bacteria in different periods. Candidatus solibacter and Bryobacter were significantly higher in T1 and T3 than in T1 and T4. Bradyrhizobium flora increased significantly at T3. Sphingomonas increased significantly at T1 (p < 0.05).

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.