The study was aimed to clarify the effects of different bag types on fruit quality and postharvest storage of Dongshizao pomelo, and screen suitable bag types to provide reference for production and application. In this study, 23-year-old Dongshizao pomelo trees were used as the experimental material, fruit without bagging was used as the control group, fruit bagging was carried out with 8 types of bags, including 60-mesh nylon mesh bag, 80-mesh nylon mesh bag, unilateral polyethylene-paper bag, white nonwoven bag, green-single-layer bag, white-single-layer bag, single-layer bag with yellow outside and black inside, double-layer bag with yellow outside and black inside. Fruit quality difference between harvest and post-harvest storage was compared, and comprehensive evaluation was carried out by the subordinative function method. The results showed that the white-single-layer bag significantly increased the single fruit weight by 47.86%, double-layer bag with yellow outside and black inside significantly decreased the pericarp thickness by 28.19%, and the total soluble solids (TSS) content of fruits with single-layer bag with yellow outside and black inside was significantly decreased. The titratable acid (TA) content of fruits with unilateral polyethylene-paper bag, single-layer bag with yellow outside and black inside, double-layer bag with yellow outside and black inside were decreased. While the single-layer bag with yellow outside and black inside, double-layer bag with yellow outside and black inside were significantly improved the TSS/TA rate by 19.71% and 34.40%, respectively. At harvest, the comprehensive evaluation of fruit quality revealed that fruits bagged with the double-layer bag with yellow exterior and black interior achieved the highest score (0.56), followed by those with the single-layer bag of the same design (0.55), both outperforming the unbagged control (0.50) and white single-layer bag (0.49). During postharvest storage, the fruit weight loss rate generally increased with storage duration, except for one transparent paper bag treatment, and peaked on the 45th day of storage. Throughout the storage period, significant differences were observed in various fruit quality indices, including edible rate, juice yield, soluble sugar, soluble protein, TSS, and TA content, with fluctuations influenced by bag type. Regardless of treatment, the inherent quality indices of the fruit pulp exhibited significant variability rather than a simple upward or downward trend. The bagged fruits also displayed a distinct ‘returned acidity’ phenomenon, with the timing and intensity of this phenomenon influenced by the type of bag used. The comprehensive evaluation of postharvest storage quality showed that the average comprehensive score of fruits bagged with the white single-layer bag gradually increased with extended storage time, reaching the highest average score (0.65) among all treatments, with the smallest coefficient of variation (5.14%). In conclusion, while fruits bagged with the single-layer and double-layer bags with yellow exterior and black interior demonstrated superior comprehensive quality at harvest, they exhibited greater quality fluctuations and poorer storage stability. Conversely, although the initial harvest quality of fruits bagged with the white single-layer bag was slightly inferior to the control, this treatment exhibited the smallest variation range in storage quality, coupled with the highest overall storage quality and stability. Therefore, the white single-layer bag is recommended as the primary bagging option for the production and cultivation of Dongshizao pomelo, offering a balanced approach to optimizing both fruit quality and postharvest storage performance.

The study aimed to find non-toxic and pollution-free post-harvest prevention and treatment methods replacing chemical fungicides to enrich the resources of mango stalk rot antagonist bacteria. Botryodiplodia theobromae Pat. and Phomposis mangiferae Ahmad were used as the indicator fungi, and actinomycetes with antagonistic effects on stalk rot fungi were isolated and screened from the rhizosphere soil of mango trees by the plate dilution and dual culture method. The classification status, live prevention effects, and the antimicrobial mechanism were preliminary studied. Antagonists A2, B85 and D16 were selected, which had antimicrobial effects and good genetic stability against both Botryodiplodia theobromae Pat. and Phomposis mangiferae Ahmad, and had inhibitory effects on Colletotrichum gloeosporioides, Pestalotiopsis mangiferae, Alternaria alternate and Botrytis cinerea, with a wide antifungal spectrum. In the live test, on the 3^rd day after inoculation, there were no significant differences in the diameter of the fruit lesions treated with antagonist strains A2, B85 and D16 (8.58, 8.50, 7.83 mm) and the imimerine-treated group (6.33 mm), but significantly lower than that of the control group (20.58 mm). Strains A2 and B85 were identified as Streptomyces malaysiensis, and D16 was Streptomyces lydicus. Strains A2, B85 and D16 inhibited the occurrence of pedicle rot by producing active substances with antimicrobial effects, inhibiting spore germination of dipodol, nutritional competition, and improving the activity of fruit SOD, POD and CAT. Among the three antagonistic strains, the D16 could also produce volatile organic compounds with antimicrobial effects to inhibit the occurrence of pedicle rot fungi. The three strains had certain antagonistic effects on pedicle rot bacteria and could be further studied.

Banana anthracnose, caused by Colletotrichum musae, is a major postharvest disease that threatens fruit quality and banana industry sustainability. Phospholipase (PL) plays dual roles in plant disease resistance and pathogen metabolism, acting as a key enzyme in defense responses and as a virulence factor for pathogenic fungi.. Previous studies have shown that PL inhibitors can help maintaining membrane stability under stress conditions. In this study, the inhibitory effects of three PL inhibitors, i.e. quinacrine dihydrochloride (QU), neomycin sulfate (NE), and n-hexanol (Hex), on C. musae were evaluated through in vitro antifungal assays. Results showed that all three inhibitors significantly suppressed mycelial growth and spore production of C. musae. The half-maximal inhibitory concentrations (IC₅₀) for mycelial growth were 1.00 mmol/L (QU), 5.00 mmol/L (NE), and 8.80 mmol/L (Hex). Enzymatic activity assays revealed that QU significantly inhibited both PLA activity in C. musae and banana peel tissues, NE primarily suppressed PLC activity in banana peel, whereas Hex markedly reduced PLD activity in C. musae. Moreover, the appropriate concentrations of the inhibitors (2.00 mmol/L QU, 3.00 mmol/L NE, and 13.20 mmol/L Hex) effectively controlled the development of banana anthracnose. The findings suggested that QU, NE, and Hex suppressed banana anthracnose through distinct mechanisms involving interference with host-pathogen interactions. This study would provide a theoretical basis for the green control of postharvest banana diseases via the targeted regulation of phospholipase activity.

Cymbidium mosaic virus (CymMV) and Odontoglossum ringspot virus (ORSV) are common viruses in Phalaenopsis production, and monitoring CymMV and ORSV of in vitro seedlings is the foundation of high-quality and healthy seedling production in Phalaenopsis. In this study, 20 Phalaenopsis cultivars were used as the research objects. Two batches of in vitro seedlings selected from the production line with 10-month intervals between the subculture proliferation cycles, were investigated for CymMV and ORSV through RT-PCR (reverse transcription polymerase chain reaction) and RT-qPCR (real time quantitative polymerase chain reaction) at the same time. RT-PCR results showed that the positive rate of CymMV in the first and second batch was 25% and 20%, respectively, and the positive rate of ORSV was both 15% in the two batches. RT-qPCR results showed that the positive rate of CymMV in the first and second batch was 100% and 91.67%, respectively, and the positive rate of ORSV in the two batches was 50% and 25%, respectively. Comparing with the first batch, CymMV content of 16 cultivars and ORSV content of 9 cultivars decreased in the second batch, but ORSV content of Phalaenopsis Sogo Yukidian V3 increased significantly, which increased from negative to 6.85×10⁵-8.50×10⁵ copies/μL. The results indicated that CymMV and ORSV widely existed in in vitro seedlings of Phalaenopsis, and the content varied with different batches. The cultivars detected as the negative also faced the risk of virus content increase. Thus, CymMV and ORSV should be investigated regularly in the production of in vitro Phalaenopsis seedlings to ensure the high-quality seedling source for Phalaenopsis industry.

Natural rubber latex serves as the primary raw material for various products, including medical gloves, condoms and tires. Enhancing its formulation can effectively reduce production costs, improve product performance, and enhance the competitiveness of manufacturing industry. In this study, a spherical symmetric design method was employed to optimize the rubber compound formulation. Sulfur, zinc oxide, accelerator UH-301 and antioxidant WSL were selected as key components for the formulation. The investigation focused on three comprehensive indicators: elongation at break, tear strength and tensile strength. The indicators were analyzed through hypothesis modeling, regression analysis and programming solutions to determine the optimal formulation. The vulcanization characteristics and mechanical properties of both the optimized formula and the basic formula for latex vulcanization were tested. The results indicated that the optimized formula (sulfur: 1.50 phr, zinc oxide: 0.25 phr, accelerator UH-301: 0.40 phr, antioxidant WSL: 1.36 phr) was obtained via regression analysis, with an estimated comprehensive strength of 1.2891. Verification tests confirmed the feasibility of the mathematical model constructed using the spherical symmetrical design method. Comparing the optimized formula with the basic latex vulcanization formula revealed that the former significantly outperformed the latter in vulcanization rate and physical-mechanical properties. Specifically, the tensile strength of the vulcanized rubber film with the optimized formula reached 32.2 MPa, an increase of 212.4%, while the tear strength reached 60 kN/m, an increase of 180.1%. The findings further demonstrate the practical application value of the optimized rubber compound formulation and would provide a solid foundation for enhancing the performance of natural latex rubber films.

Ammonia preservation and acid solidification are key steps in natural rubber (NR) processing, but there is still a lack of systematic research on the influence on the structure and properties of NR. In this paper, the same batch of fresh latex was treated with 0%, 0.05%, 0.20% ammonia and two solidification methods (acid solidification, biological solidification) to prepare samples. The effects of ammonia preservation and acid solidification on the structure and properties of NR were comprehensively evaluated from the aspects of molecular structure, composition, intrinsic properties, and the mechanical performance of both unfilled and carbon-black-filled vulcanizates. It was found that ammonia preservation led to a decrease in weight-average molecular weigh, the initial plastic value and Mooney viscosity of the acid-solidified samples, whereas the properties remained largely unaffected in biologically solidified counterparts. The addition of ammonia exerted minimal influence on the mechanical properties of unfilled vulcanizates, but significant effects emerged in carbon-black-filled systems. Acid-solidified samples demonstrated higher fatigue temperature rise, while biologically solidified samples showed decreased tensile stress and tear strength. The solidification mode profoundly impacted the molecular structure, chemical composition, intrinsic properties, and mechanical performance of NR. Compared to biological solidification, acid-solidified rubber exhibits higher nitrogen, free fatty acid content and weight-average molecular weight. Furthermore, acid-solidified samples displayed lower initial plasticity and Mooney viscosity. The solidification method significantly affected the properties of both unfilled and carbon-black-filled vulcanizates. Compared to biological solidification, acid-solidified samples exhibited slower cure rates and higher fatigue temperature rise. The results showed that ammonia preservation of fresh latex and subsequent solidification with acid could affect the important components and intrinsic properties of NR, and had a significant impact on the dynamic properties such as fatigue temperature rise and permanent deformation, especially in carbon-black-filled vulcanizates. However, by comparing with the imported RSS, the preservation of fresh latex with ammonia and the subsequent solidification with acid were not the only reasons causing the performance of domestic NR to be worse than that of imported NR and differences in processing maybe the other causes. This work not only reveals the reason of the performance difference between domestic and imported NR products, but also would provide technical support for optimizing the production management of special rubber park.

Coconut water is sterile in the interior cavity of the coconut fruit. However, once the coconut is opened and repackaged, the coconut water beverage may become a breeding ground for bacteria and fungi, leading to the production of harmful mycotoxins. This study aimed to detect the usage of preservatives and sweeteners, also the levels of the common carcinogenic contaminant benzo[a]pyrene and harmful mycotoxins in bottled coconut water sold on the market. By using national standard methods, no preservative such as benzoic acid and sorbic acid, no sweetener sodium saccharin, and no contaminant benzo[a]pyrene were detected in this batch of coconut water beverages. This study also investigated the level of mycotoxins in bottled coconut water stored at low temperatures (4-8 ℃) for 21 days. No zearalenone (ZEN) or deoxynivalenol (DON) was detected in the coconut water stored at 4-8 ℃ for 21 days. During monitoring, the response signal for aflatoxin B₁ (AFT B₁) in one of the samples had an increasing trend with prolonged storage time but the level did not exceed the quantitative limit specified in the national standard method. Electron microscope observation of the bottled coconut water stored at low temperatures revealed a large number of moving microorganisms in 1-3 days, with the aerobic plate count increasing exponentially. After 21 days of low-temperature storage, infrared spectra showed new characteristic absorption peaks, indicating that the coconut water had undergone qualitative changes. It is recommended that bottled coconut water from freshly cut coconuts should be consumed on the same day.

The effects of exogenous ethylene (ETH), 1-methylcyclopropene(1-MCP) and a combined ETH+1-MCP treatments on fruit storage quality and physiological changes were evaluated to investigate the effects of ethephon on the fruit appearance color and internal quality during the ripening process of mangoes Hongguifei. The results showed that compared with the control, both ETH and ETH+1-MCP treatments significantly accelerated the decline in fruit firmness, titratable acid, chlorophyll, flavonoids, total phenolics, and ascorbic acid content, increased cell membrane permeability, and promoted in a^* color value, total soluble solids (TSS) in the early stage of storage, and carotenoid. Among the treatments, the ETH+1-MCP group showed the highest level of TSS and carotenoids while 1-MCP group effectively delayed the loss of nutrients and firmness, and inhibited chlorophyll degradation in the fruit peel. Further analysis of the metabolomes of the CK and ethylene treatment groups revealed 140 different metabolites, among which 88 were upregulated and 52 were downregulated. The content of flavonoids in the fruits of the ETH treatment group was significantly lower than that of the control group, indicating that the ETH treatment accelerated the degradation of flavonoids. This study revealed the metabolic mechanism of ETH in promoting the ripening and quality formation of mangoes, which would provide a theoretical basis for in-depth research on the mechanism of post-ripening quality changes in mangoes.

Biogenic volatile organic compounds (BVOCs) are important secondary metabolites released by forest plants, playing a crucial role in plant growth, development and environmental regulation. This study focused on rubber trees (Hevea brasiliensis) widely cultivated in Hainan Island. Using dynamic headspace sampling coupled with thermal desorption-gas chromatography-mass spectrometry (GC-MS), we systematically analyzed the emission characteristics of BVOCs and the environmental influencing factors across rubber trees of different stand ages (5, 15, 20 and 25 years). The diurnal variation of BVOCs exhibited a unimodal curve, with peak emissions concentrated between 10:30 and 13:00. BVOC emission rates decreased significantly with increasing stand age (5 years >15 years >20 years >25 years), and emissions during the rainy season were significantly higher than those during the dry season. The diversity of monoterpenes (MTs), other terpenes (OTs) and oxygenated volatile organic compounds (OVOCs) decreased with stand age, while sesquiterpenes (STs) remained stable. BVOC emissions showed significant positive correlations with net photosynthetic rate, transpiration rate, and light intensity (P<0.05), with light intensity being the primary influencing factor. The effects of air temperature and humidity on BVOC emissions increased with stand age. This study elucidated the age-related effects and seasonal dynamics of BVOC emissions in rubber plantations, providing a scientific basis for assessing the ecological and environmental impacts of tropical artificial forests.

The maize leaf area index (LAI) is a key parameter for reflecting growth and yield of maize, and the pollination stage being crucial for determining ear kernel number and yield. This study aimed to identify an effective inversion method to accurately estimate the LAI of Nanfan maize at pollination stage. Nanfan maize at pollination stage was used as the study subject. Canopy reflectance data were acquired using a ULTRIS X20 PLUS hyperspectral imager mounted on a Jingwei M300RTK quadrotor UAV platform. Based on correlation analysis, 28 LAI-sensitive vegetation indices were selected. Two traditional empirical models, univariate linear regression (ULR) and multiple stepwise regression (MSR), and four machine learning models, partial least squares regression (PLSR), random forest regression (RFR), support vector regression (SVR) and back propagation neural network (BPNN) were employed to construct LAI inversion models. The prediction accuracy of different vegetation indices and regression algorithms was compared, and the optimal inversion model was selected for accurately predicting the LAI status of Nanfan maize at pollination stage. Most vegetation indices exhibited highly significant correlations with LAI (P<0.01). Compared to univariate regression, multivariate regression models provided higher prediction accuracy. Among them, RFR, MSR and PLSR models achieved the highest R² values, with coefficients of determination (R²) of 0.96, 0.85 and 0.80 and corresponding root mean square errors (RMSE) of 0.18, 0.35 and 0.41, respectively. By analyzing the correlation and sensitivity between hyperspectral data and maize LAI, and employing vegetation indices calculated based on hyperspectral information combined with regression algorithms, this study successfully developed a reliable LAI inversion model, and established a spatial distribution of Nanfan maize LAI at pollination stage based on the RFR model with the best inversion effect. The model would provide both theoretical support and technical guidance for LAI estimation and field monitoring of Nanfan maize growth and development.