The study developed a new fresh-eating sweet potato variety Guishu No. 13 and established its virus-free seedling breeding technology system to meet the market demand for fresh-eating sweet potato varieties and healthy seedlings. Guishu No. 13 was bred from seeds by open pollinated using Guizhu No. 10 as mother. The variety has purple red skin, orange yellow flesh, and a high rate of medium to large storage roots. The content of β-carotene, protein and reducing sugar was 1790 mg/100 g, 1860 mg/100 g and 1200 mg/100 g, respectively. In the production experiment, the starch storage roots yield was 29 786.40 kg/hm² and starch yield was 4675.10 kg/hm², which increased by 5.52% and 17.52% respectively compared to Guishu No. 2 (CK). Guishu No. 13 has moderate resistance to Fusarium wilt, black rot, and stem nematode. The best culture medium for callus differentiation and germination rate of Guishu No. 13 was MS+0.10 mg/L NAA+1 mg/L 6-BA and MS+0.20 mg/L NAA+2 mg/L 6-BA, respectively. Guishu No. 13 has good yield and stability, high fresh storage root yield, and the establishment of a virus-free breeding system would lay the foundation for the development and application of the Guishu No. 13.

The identification and evaluation of superior germplasm are the foundation for the research on germplasm resources and breeding utilization. 45 citronella grass resources from Hainan, Fujian, Guizhou, Yunnan and other regions were assayed to evaluate the essential oil content. The agronomic traits, essential oil content and main components of essential oil of the resources at different cutting stages were analyzed in Kunming. The results showed that there were significant differences in total grass length, leaf length, leaf width, biological yield and essential oil content among different cutting periods and different materials. Correlation analysis between characteristic traits and essential oil content revealed that the essential oil content was significantly negatively correlated with leaf length and significantly positively correlated with leaf width. Systematic cluster analysis based on agronomic traits and essential oil content divided the resources into 5 groups. The Ⅰ group contained 36 materials, and all materials were identified as Cymbopogon citra=tus, The Ⅱ group had 4 materials, all in Cymbopogon winterianus. Cymbopogon caesius and Cymbopogon hamatulus were individually clustered into the Ⅳ and Ⅴ groups, respectively. A standard for identifying and grading superior germplasm oriented towards essential oil yield was established, and the 45 resources were divided into three grades, including 6 in the first grade, 18 in the second grade and 21 in the third grade. In addition, the analysis of essential oil content and main components of 16 germplasm in Yuanmou test region at 6 different periods showed that the accumulation of essential oil did not increase with the extension of planting time, and the contents of main components in essential oil also varied in different periods. Geraniol reached the highest value in January; Linalool had the highest content in March; Geranyl acetate peaked in September; Citronellyl acetate had the highest content in January, and β-myrcene was the highest in May. This study would provide a scientific basis for the identification and evaluation of superior citronella grass germplasm, breeding utilization, and the production and utilization of high-quality and high-yield raw materials.

1-year-old and 5-year-old Alpinia galanga intercropped under rubber forests was used to understand the photosynthetic physiological characteristics of Alpinia galanga in rainy and dry season, explore its growth adaptability and growth habits, and provide a theoretical basis for its popularization under rubber forests. There were significant differences in photosynthetic parameters between 1-year-old and 5-year-old plants. The net photosynthetic rate (P_n) and transpiration rate (T_r) of 1-year-old plants were higher than those of 5-year-old ones, and T_r was higher in rainy season than in dry season, indicating drought tolerance and stronger photosynthetic capacity in seedlings. There existed differences in light response curve parameters. Light saturation point (LSP) and light compensation point (LCP) of both age groups were between those of heliophytes and sciophytes, confirming shade tolerance. LSP and apparent quantum efficiency (AQE) were higher, while LCP was lower in the dry season, further indicating drought tolerance. The maximum photochemical efficiency (F_v/F_m) was slightly higher in the dry season, suggesting stronger photosynthetic capacity. Contents of chlorophyll a, chlorophyll b, total chlorophyll, and Chl a/b ratio were higher in the dry season, indicating more favorable growth conditions. The 5-year-old plants had thicker upper epidermis and higher palisade-spongy ratio, adapting to shade and drought under rubber forests. The spongy tissue thickness exceeded that of palisade tissue in both age groups, confirming shade tolerance. In conclusion, Alpinia galanga is shade/drought-tolerant with high weak-light utilization. This indicates that dry season conditions and appropriate shading (shading degree of 40%-80%) are more conducive to the growth of Alpinia galanga.

This study aimed to study the effects of long-term grass planting on soil fertility, enzyme activity and microbial diversity in tropical latosol soil, providing theoretical and technical support for improving the fertility and amelioration of tropical latosol soil. Using clean tillage as the control and three grass-planting treatments were established: Reyan No. 2 Stylosanthes (Re) and Ubon Stylosanthes (Ub) and natural grass (NG). Soil samples from 0-20 cm and 20-40 cm layers were collected to measure soil organic matter, pH, nitrogen, phosphorus, potassium and related enzyme activities. Utilizing a high-throughput sequencing platform to analyze soil bacterial and fungal communities, and investigating the effects of long-term orchard grass cultivation on the physical and chemical properties, enzyme activity, and microbial diversity of latosol soil. Five years of grass cultivation significantly increased soil organic matter, total nitrogen, and alkali-hydrolyzed nitrogen. with higher levels in Reiyan No. 2 and Ubon treatments compared to natural grass. Natural grass significantly increased total phosphorus in the 0-20 cm layer, while Stylosanthes treatments significantly enhanced total phosphorus in the 20-40 cm layer. Long-term grass planting significantly increased urease, acid phosphatase, and sucrase activities in both soil layers, with no notable effect on catalase activity. The Stylosanthes treatments showed higher urease, acid phosphatase, and sucrase activities than natural grass. Correlation analysis revealed that acid phosphatase, urease, and sucrase were extremely significantly positively correlated with organic matter, total nitrogen and alkali-hydrolyzed nitrogen. Acid phosphatase was significantly positively correlated with pH, while catalase only correlated significantly with organic matter, alkali-hydrolyzed nitrogen. Long-term grass cultivation, particularly the Ubon treatment, increased bacterial OTUs numbers in the 20-40 cm layer. Grass cultivation altered bacterial and fungal community compositions. The dominated bacterial phyla were Acidobacteria, Chloroflexi, Verrucomicrobia and Proteobacteria. In the 0-20 cm layer, grass cultivation increased the relative abundances of Acidobacteria, Verrucomicrobia and Proteobacteria but reduced Chloroflexi. For fungal, Ascomycota, Basidiomycota and Mucoromycota were dominant. Grass cultivation decreased Ascomycota abundance while increasing Mucoromycota. Soil environmental factors significantly influenced microbial communities. Acid phosphatase, organic matter, urease and pH were key drivers of bacterial community changes, whereas organic matter, total nitrogen, alkali-hydrolyzed nitrogen, sucrase and urease primarily shaped fungal community structure. Long-term grass cultivation in orchards, particularly Stylosanthes, significantly increased the organic matter, total nitrogen, and alkali-hydrolyzable nitrogen content in latosol soil. It also enhanced the activities of soil urease, acid phosphatase, and invertase enzymes. Furthermore, it altered the community structure and diversity of both soil bacteria and fungi, thereby effectively improving soil fertility and ameliorating the soil micro-ecological environment.

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.

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 study determined quality indexes including single fruit mass, longitudinal and transverse fruit diameter, peel thickness, edible rate, soluble solids and titratable acid of 51 pomelo accessions to analyze the fruit quality characteristics of different pomelo germplasm resources and establish a comprehensive evaluation system. Correlation analysis and principal component analysis were employed to comprehensively evaluate the fruit quality. The fruit longitudinal diameter ranged from 64.00 to 191.00 mm, with transverse diameter measured between 76.00 and 170.90 mm. Fruit shape index values varied from 0.82 to 1.35, while single fruit mass spanned 220.00 to 1750.00 g. Peel mass was recorded between 50.00 and 996.00 g, with edible rates from 19% to 81%. Peel thickness measurements showed variation from 4.00 to 39.67 mm. Segment number per fruit was 10-20, soluble solids content ranged 4.50%-10.90%, and titratable acid level was 0.13%-2.96%. The solid-acid ratio varied between 2.70 and 41.70, with number of seeds ranging from 0 to 224. It indicated that the phenotypic diversity of pomelo germplasm resources in Hekou, Yunnan was rich. Pearson correlation analysis revealed that longitudinal diameter exhibited significant positive correlations with fruit shape index and single fruit mass. Transverse diameter showed extremely significant positive correlations with single fruit mass and peel mass. Significant negative correlations were observed between edible rate and peel thickness, titratable acid and solid acid ratio. Cluster analysis grouped the resources into approximately four categories, with each group displaying substantial difference in both external appearance and internal quality. By principal component analysis (PCA), the 13 traits were integrated into 4 principal components, and the contribution rate of the first principal component was 31.614%. The longitudinal diameter, transverse diameter, single fruit mass and peel mass contributed more. The contribution rate of the second principal component was 16.842%, which was based on edible percentage, number of segments and soluble solid. The contribution rate of the third principal component was 15.397%, and the contribution rate of titratable acid was larger. The contribution rate of the fourth principal component was 14.686%, which was based on the number of seeds. After fruit quality analysis and comprehensive evaluation, Yunqing 1, Green peel and red flesh Pomelo, Huangjin pomelo, Guanxi red flesh pomelo, Dongshizao Pomelo, and Wanbai Pomelo demonstrated superior comprehensive quality and were recommended as candidate materials for main cultivars or breeding parents in Hekou, Yunnan.

10 inflorescence traits of 200 domestic and international Macadamia germplasms in the Jinghong Macadamia Germplasm Repository of the Ministry of Agriculture and Rural Affairs were evaluated using QGA Station combined with different genetic distance metrics, clustering methods, sampling strategies, and sampling proportions to conduct a core macadamia collection construction. The optimal methodology for core collection development was identified as “Mahalanobis distance+multi-clustering deviation sampling+centroid clustering method+15% sampling proportion”, resulting in a core collection comprising 30 accessions. The mean difference percentage, variance difference percentage, range coincidence rate and variation coefficient change of core collection and original collection was 0.00%, 90.00%, 99.31% and 150.08%, respectively. No significant differences in trait means were detected between the core and original collections (T-test). The variances of all traits in the core collection exceeded those of the original collection, with 9 traits showing statistically significant differences. While genetic diversity indices slightly decreased, the conformity rate for all traits remained above 80%. Principal component analysis (PCA) demonstrated that the cumulative variance contribution rate of the first three principal components was 74.118% and 84.350% for the original and core collections, respectively, with congruent geometric structures in their PCA scatterplots. Correlation analysis further confirmed that trait relationships in the core collection closely mirrored those of the original collection. The core collection comprised 8 Australian accessions, 10 Hawaiian accessions, 9 China Yunnan accessions, and 3 accessions of special types, exhibiting a degree of geographic representativeness. Analyses using both cluster analysis and PCA on the core collection revealed that domestic and foreign accessions were distinguishable to a certain extent based on the inflorescence phenotypes. The Macadamia core collection developed in this study, based on inflorescence phenotypic traits, effectively represents the genetic diversity of the original collection and would provide a robust foundation for future research on Macadamia genetic resources.

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.

Sweet potato (Ipomoea batatas) is a globally significant food and functional crop, with its purple-fleshed varieties drawing particular attention due to the high anthocyanin content. Anthocyanins not only give the tubers distinct color but also possess antioxidant, anti-inflammatory, and disease-preventive physiological functions, making them highly valuable in the development of health foods. However, the biosynthesis of anthocyanins is regulated by a multi-level network, and the role of bHLH transcription factors in sweet potatoes has not been fully elucidated. This study focused on the sweet potato gene Tai6.33665, aiming to clarify its molecular characteristics, subcellular localization pattern, and regulatory role in anthocyanin accumulation, providing a theoretical basis for molecular breeding of high-anthocyanin sweet potato varieties. Using purple-fleshed sweet potatoe (PFSP) and white-fleshed sweet potatoe (WFSP) as materials, the study analyzed the protein structure and evolutionary relationship of Tai6.33665 through bioinformatics, detected the gene expression pattern using qRT-PCR, constructed a Tai6.33665-GFP fusion vector for transient transformation in tobacco, determined the subcellular localization using laser confocal microscopy, and analyzed the correlation between gene expression and anthocyanin content and the miRNA interaction mechanism. The results showed that the protein encoded by Tai6.33665 had a typical bHLH domain and was highly homologous to anthocyanin synthesis regulatory factors. Its expression level was significantly negatively correlated with anthocyanin accumulation (P<0.05), and it was targeted and inhibited by ib-miR52. Subcellular localization indicated that the protein was located in the endoplasmic reticulum, suggesting that it might indirectly regulate metabolism through post-translational modification or the endoplasmic reticulum pathway. This study confirmed that Tai6.33665 acted as a negative regulator of anthocyanin biosynthesis in sweet potatoes, and its function depended on subcellular localization specificity and miRNA-mediated post-transcriptional regulatory networks. This discovery not only enriches the theoretical framework of plant secondary metabolism regulation but also provides a dual-track strategy for molecular breeding by targeting knockout of Tai6.33665 or overexpression of ib-miR52 using CRISPR/Cas9, the genetic limitations of anthocyanin accumulation could be overcome, and new high-anthocyanin sweet potato varieties could be developed. Future work would focus on elucidating the interaction mechanism between the gene and MYB/WD40 proteins, as well as the regulatory pathway of its transcriptional activity by endoplasmic reticulum localization.