Leguminous green manure cover cropping and incorporation play a crucial role in improving soil conditions and enhancing nutrient cycling in ecosystems. Studying the decomposition characteristics and nutrient release patterns of green manure is of significant importance for the sustainable production of rubber plantations. This study selected four representative tropical leguminous green manures: Pueraria phaseoloides Benth (GT), Crotalavia anagroides H.B.K (ZSD), Tephrosia candida DC. (SMD), and Stylosanthes guianensis (Aubl.) Sw. (ZHC). During the vigorous growth period of the green manures, a 260-day field in-situ decomposition experiment was conducted using the nylon mesh bag method to explore the decomposition characteristics and nutrient release patterns of the leguminous green manures from different genera. The dry matter decomposition characteristics followed the “Olson” exponential model. The decomposition constants (k) ranked as follows, GT (3.01)>SMD (2.51) and ZHC (2.36)>ZSD (2.01), with GT being significantly higher than ZSD (P<0.05). At the end of the experiment, the dry matter remaining rate of the four green manures was ZSD (24.7%)>SMD (22.7%)>ZHC (21.7%)>GT (17.3%). The time required for 95% decomposition was 17.9, 15.3, 14.3, and 11.9 months, respectively. For carbon (C), nitrogen (N), phosphorus (P), and potassium (K), the remaining rate across the four green manures (GT, ZSD, SMD, ZHC) was N (15.5%–34.0%)>P (11.9%–30.4%)>C (15.1%–22.2%)>K (0.58%–1.07%). Calcium (Ca) and magnesium (Mg) residue ratea was Ca (45.0%–64.0%)>Mg (11.5%–31.9%). Iron (Fe), copper (Cu), and zinc (Zn) showed average residue rate of 160.9%, 138.3%, and 110.6%, respectively, indicating enrichment effects, while manganese (Mn) had an average residue rate of 36.3%. Notably, GT exhibited complete nutrient release for all elements, with the lowest remaining rate among the four green manures. In contrast, ZSD, SMD, and ZHC demonstrated enrichment effects for Fe, Cu, and Zn. In conclusion, the differences in decomposition and nutrient release characteristics among green manures would provide critical theoretical support for nutrient cycling and soil fertility improvement in rubber plantations, and technical guidance for sustainable rubber plantation management.

Coconut wood (Cocos nucifera L.), an economically significant tropical tree, exhibits variations in fiber morphology and chemical composition that directly influence its processing performance and comprehensive utilization potential. This study systematically investigated the spatial variability of fiber morphological indices (length, width, cell wall thickness, lumen diameter, aspect ratio, and cell wall-lumen ratio) and chemical components (holocellulose, cellulose, and lignin) across different trunk heights (bottom, middle, top) and radial positions (outer, middle, inner) in 40-year-old coconut trees from Hainan. The analyses were conducted using wood microscopy, image analysis software, and chemical assays. Fiber length (696.84–969.94 μm), cell wall thickness (9.78–18.36 μm), and cell wall-lumen ratio (1.13–5.82) decreased significantly from the bottom to the top, while lumen diameter (3.60–10.15 μm) increased. Fiber width (17.41–20.76 μm) and aspect ratio (40.39–48.79) showed minor variations but exhibited an overall downward trend with increasing height. Fiber length, cell wall thickness, and cell wall-lumen ratio decreased from the outer to inner regions, whereas lumen diameter increased. Chemical analysis indicated decreasing trends for holocellulose (59.14%–70.32%) and cellulose (41.03%–44.85%) content along both vertical and radial gradients, while lignin (21.40%–23.60%) initially decreased and then increased vertically, with higher inner-region content. The study identified superior fiber morphology (longer fibers, thicker cell walls, smaller lumen diameters) and higher holocellulose and cellulose content in the bottom and outer regions. Compared to bamboo, coconut fibers are thicker, with thicker cell walls and smaller lumens but lower aspect ratio, making them particularly suitable for medium-to-short fiber pulping processes. This research elucidates the spatial variation mechanisms of coconut wood fiber morphology and chemical composition, could providing a theoretical foundation for optimizing pulping, fiberboard manufacturing, and bioenergy applications, Such insights can enhance resource utilization efficiency and support sustainable development in tropical timber industries.

In this study, Cymbopogon winterianus was used as the experimental material, and the DNA sequence of C. winterianus was sequenced using the Illumina NovaSeq 6000 sequencing platform. The sequencing data were assembled with GetOrganelle v1.7.7.0 software to construct the chloroplast genome. Referring to the known chloroplast genome of C. flexuosus, the chloroplast genome of C. winterianus was annotated, and the genomic characteristics were analyzed and a phylogenetic tree was constructed. The chloroplast genome of C. winterianus was 139 823 bp in length, with a typical circular quadripartite structure. The GC content was 38.45%, and the AT content was 61.55%. It included a large single-copy region (LSC) with a length of 82 214 bp, a pair of inverted repeat regions (IR) with a length of 21 368 bp, and a small single-copy region (SSC) of 14 873 bp. A total of 130 genes were annotated in the chloroplast genome of C. winterianus (including 85 mRNA genes, 37 tRNA genes, and 8 rRNA genes). In addition, among the annotated genes, there were 16 double-copy genes, accounting for 12.31%, including 7 tRNA genes, 4 self-replication genes, 4 rRNA genes, 2 protein genes with unknown functions, and 1 NADH dehydrogenase subunit gene. A total of 144 SSR loci were detected in the chloroplast genome of C. winterianus, with mononucleotide repeats being absolutely dominant, mainly A/T. After comparing the boundaries of the inverted repeat sequences of four Cymbopogon species, it was found that C. flexuosus, C. pospischilii, and C. winterianus exhibited extremely high homology in gene structure and species. Among them, the ndhH gene was located in the small single-copy region (SSC), and the ndhF gene was located in the boundary region between the SSC and IRb. However, C. winterianus had an additional rps3 gene in the LSC region compared with C. flexuosus and C. pospischilii. Phylogenetic tree analysis showed that C. winterianus had the closest genetic relationship with C. pospischilii and C. citratus (MK593547.1). This study completed the assembly and annotation of the complete chloroplast genome of C. winterianus, analyzed the characteristics of the chloroplast genome of C. winterianus, and preliminarily explored the phylogenetic position of C. winterianus within the genus Cymbopogon. It would lay a good foundation for the phylogenetic, genetic diversity, and genomic studies of Cymbopogon plants, as well as for the discovery and utilization of important functional genes.

Chitinase plays a crucial role in plant stress resistance and growth development. To elucidate the effects of plant hormones and environmental stress on the expression of the mustard chitinase gene, this study investigated three plant hormones-salicylic acid (SA), 1-amino-cyclopropane-1-carboxylic acid (ACC), and methyl jasmonate (MeJA)—and the influence on the transcriptional regulation of the chitinase gene family in Brassica oleracea cv. BaiHua. Additionally, seedlings were subjected to two stress conditions: infection by Pectobacterium carotovorum subsp. Brasiliense and exposure to high temperature. The transcriptional levels of the Chinese kale chitinase gene family members were analyzed using the quantitative real-time polymerase chain reaction (qRT-PCR) method. Results demonstrated that among the 18 genes within the chitinase gene family of Chinese mustard, 16 exhibited significant induction under soft rot fungal infection, while 8 responded to high-temperature stress. Furthermore, all 18 genes showed responsiveness to plant hormone-induced expression. This study highlights the potential role of the chitinase gene in mediating responses to hormonal signals and environmental stress, thereby contributing to stress resistance and growth development in plants. The findings would provide valuable insights for future molecular breeding strategies targeting Chinese kale.

China is currently the largest sweet potato producer globally. The postharvest starch and soluble sugar (glucose, fructose, and sucrose) contents in storage roots not only influence sweet potato utilization and commercial value (including taste, nutritional quality, and food processing properties), but also affect sprouting, weight loss, and decay during storage and transportation. Studies on tubers/roots such as potato and carrot have demonstrated that vacuolar invertase (VIN) serves as the primary sucrose-cleaving enzyme determining postharvest sugar composition and content. However, the key sucrose-cleaving enzyme regulating postharvest sugar metabolism in sweet potato storage roots remains unclear. This study systematically investigated sugar metabolism characteristics in storage roots of ‘Kokei 14’, a major sweet potato cultivar in Hainan Province, under room temperature storage (25 ℃) and low-temperature storage (15 ℃), aiming to identify the principal sucrose-cleaving enzymes affecting postharvest sugar composition and content. Low-temperature storage enhanced preservation quality by reducing dry matter loss and sprouting rate through suppression of hexokinase (HK) activity and respiratory intensity. Compared with room temperature storage, low-temperature treatment induced greater increases in soluble sugar (glucose, fructose, and sucrose) content and more pronounced starch degradation, accompanied by significantly higher β-amylase activity, indicating that low-temperature storage promotes starch hydrolysis into soluble sugars. During room temperature storage, cell wall invertase (CWIN) and sucrose synthase (Sus) activities generally declined, while VIN activity initially increased before returning to baseline levels. Notably, cytoplasmic invertase (CIN) activity exhibited a continuous upward trend, suggesting CIN as the key sucrose-cleaving enzyme responsible for hexose accumulation under ambient conditions. Conversely, low-temperature storage induced continuous declines in all three invertase activities but progressively increased Sus activity, indicating Sus as the predominant enzyme mediating hexose accumulation under cold storage. Transcriptional analysis identified IbCIN4 as the key gene family members regulating CIN activity elevation at room temperature, while IbSus6 was determined as the primary regulator of Sus activity enhancement under low-temperature conditions. This study reveals that different postharvest storage temperature induces shifts in the predominant sucrose-cleaving enzymes governing hexose accumulation in sweetpotato storage roots. Notably, our findings contrast with previous reports on potato tubers under cold storage, demonstrating that Sus rather than VIN serves as the key enzyme regulating hexose content in sweetpotato roots under low-temperature conditions. The results would establish a theoretical foundation for future genetic engineering approaches to improve postharvest quality of sweetpotato storage roots.

The study was aimed to explore the physiological response and gene expression differences of cassava seedlings under waterlogging stress and to provide theoretical basis for disaster prevention and reduction of cassava northward migration cultivation in Hunan Province. Seedlings of cassava NZ199 were used, and two waterlogging levels of moderate (W1) and severe (W2) were set. The normal water supply (CK) was used as the control. The photosynthetic characteristics and antioxidant enzyme activities of the seedlings were measured after 14 days of stress and after rewatering, and transcriptome sequencing analysis was performed on the leaves after 14 days of stress. The results showed that with the aggravation of stress, the net photosynthetic rate decreased, and the stomatal conductance, intercellular CO₂ concentration and transpiration rate showed an overall upward trend. The activities of superoxide dismutase, catalase and peroxidase were significantly higher than those of CK under waterlogging stress, the content of malondialdehyde increased, and the degree of accumulation was positively correlated with the degree of stress, indicating that the plant initiated the antioxidant mechanism when suffering from waterlogging, but still suffered a certain degree of oxidative damage. After rewatering treatment, the photosynthetic index decreased significantly compared with that before stress. Antioxidant enzyme activity and malondialdehyde content also decreased, indicating that although the plant had a certain recovery ability, it did not fully recover to the normal level before stress. The results of transcriptome sequencing showed that 900, 1542 and 575 differentially expressed genes were identified in the three comparison groups of W1 vs CK, W2 vs CK and W2 vs W1, respectively, of which 1594 were up-regulated and 1423 were down-regulated. The pathways significantly enriched by KEGG included flavonoid biosynthesis, starch and sucrose metabolism, plant hormone signal transduction, etc. In summary, cassava seedlings have certain waterlogging resistance, but the waterlogging resistance has a threshold value. Timely drainage after waterlogging helps to reduce plant damage. In this study, the physiological and gene expression changes of cassava under different degrees of waterlogging stress in Hunan were systematically analyzed, and several differentially expressed genes and pathways related to waterlogging resistance were identified, which would lay a theoretical foundation for screening candidate genes of cassava in response to waterlogging stress, and also provide a new direction for further research on the molecular mechanism of cassava waterlogging resistance and the cultivation of waterlogging resistant varieties.

Sri Lankan cassava mosaic disease, caused by Sri Lankan cassava mosaic virus (SLCMV), is a recently emerging dangerous disease in China. Existing detection methods of SLCMV are constrained by low sensitivity and poor efficiency, impeding related research and applications. Primers and probes were designed according to the gene sequences of the SLCMV, and a positive plasmid standard was prepared. The TaqMan fluorescence quantitative detection technology for SLCMV was established, and its application effect was verified. The method only generated specific fluorescence signals for SLCMV DNA samples, and the minimum detectable amount of the positive plasmid standard was 4.5×10¹ copies/μL. The standard curve showed that there was a good linear relationship between the C_t value and the logarithm of the copy number. The slope of the curve was –3.1312, the correlation coefficient R² was 0.9969, the amplification efficiency (E) was 97.9%, and the equation of the standard curve was y=–3.1312x+34.599. Using this technology to detect the tested samples from two cassava plantations in Guangxi and Fujian, the positive detection rate of leaves was 95.45% and 78.57%, respectively, and the minimum detectable copy number was 1.45×10⁵ copies/g. The virus-carrying rate of Bemisia tabaci in the field was 86%, and the minimum virus-carrying amount was 9.42×10⁴ copies/B. tabaci. This technology has good sensitivity, specificity, and repeatability, and could provide effective technical support for the monitoring and control work such as field identification, early diagnosis, and evaluation of virus-free stem cuttings of the disease.

Plant rhizosphere bacteria play a crucial role in plant nutrient uptake and utilization, and the active functional microbial communities in the rhizosphere are closely associated with high yield of crops. This study aimed to isolate, screen and identify functional bacteria from the rhizosphere soil of super high-yield rubber trees to identify beneficial strains that could potentially enhance rubber tree productivity. Using gradient dilution plating and selective medium, 60 strains of functional bacteria were isolated from the rhizosphere soil of super high yield rubber trees in Mengla Farm, Yunnan province. The isolated strains were characterized for the abilities to solubilize phosphate and potassium, fix nitrogen, and for the plant growth-promoting traits, including the production of indole-3-acetic acid (IAA), siderophores, ACC deaminase, and acetoin (3-hydroxy-2-butanone). 16S rDNA sequence analysis showed that the isolates could be classified into 12 genera, including Burkholderia, Paraburkholderia, Caballeronia, Cupriavidus, Dyella, Pseudomonas, Silvania, Enterobacter, Escherichia, Raoultella, Pantoea and Bacillus. Among these, Burkholderia was the dominant genus, comprising 40 strains (66.67%). Pot experiments with rubber seedlings demonstrated that the strain Enterobacter sp. SYK24 exhibited significant growth-promoting effects, with increases in whole plant fresh weight, aboveground dry weight, belowground dry weight and root length by 12.89%, 23.24%, 22.81% and 28.30%, respectively, compared to the control. The SYK24 treatment showed 5.01% and 18.98% reductions in total phosphorus and available potassium, respectively, compared to the control, while no statistically significant differences were observed in other soil nutrient contents. The strain Burkholderia sp. SYN37 did not promote biomass growth in rubber seedlings during the experimental period. SYN37 inoculation substantially depleted soil nutrients, resulting in reductions of soil organic matter by 31.39%, total nitrogen by 22.73%, and available potassium by 13.03% compared to the control. This study preliminarily established a small-scale functional bacterial strain library from the rhizosphere of super high-yield rubber trees, validated the growth-promoting effects of two functional strains through pot experiments, and would provide a scientific basis for the further development and application of microbial inoculants specifically tailored for rubber trees.

A comprehensive evaluation of agronomic traits of 70 varieties of fresh food tomato germplasms was conducted. Genetic diversity analysis of 28 morphological traits of the germplasms was carried out using methods such as variance analysis, principal component analysis, cluster analysis and calculation of comprehensive evaluation scores. The analysis results of genetic variability of 13 quantitative traits indicated that the variation degree of the germplasms was relatively high and the variation was rich. The variation range was 21.68%‒99.08%, and the genetic diversity index was relatively high, suggesting that the phenotypic diversity of germplasms was relatively rich and there was a significant degree of variation among the traits, indicating excellent selection potential. Among these, the traits such as single fruit weight, number of chambers, sugar-acid ratio, and transverse diameter exhibit relatively high genetic variation. The correlation analysis results showed that the traits significantly corelated with fruit firmness were the greateast in number, and fruit firmness were extremely significantly positively correlated with fruit surface ridges, fleshiness, single fruit weight, number of chambers, flesh thickness, and acidity. Sugar content was significantly negatively correlated with fruit color before maturity, and it was extremely significantly negatively correlated with fruit surface ridges, single fruit weight, number of chambers, and flesh thickness, and significantly positively correlated with plant height, and extremely significantly positively correlated with fruit shape index and soluble solids content. Single fruit weight was significantly positively correlated with leaf type, significantly negatively correlated with fruit peel color, extremely significantly positively correlated with flower sequence type and fruit surface ridges, and extremely significantly negatively correlated with fruit top shape and fruit shape. The principal component analysis results indicated that the 28 phenotypic traits could be classified into nine factors. The eigenvalues were all above 1.0, and the cumulative contribution rate reached 78.143%, which could reflect most of the information of all indicators and highlight the basic characteristics of the germplasms. Cluster analysis further divided the germplasms into five groups. The first and fourth groups had smaller tomato fruits and stronger edible properties, which could be important materials for cultivating cherry tomato varieties with good taste and high quality. The fifth group had higher hardness and larger fruits, and could be used to cultivate economic tomato varieties suitable for long-distance transportation. The comprehensive evaluation results showed that the top five germplasms were XH20-48, XH20-35, XH20-37, XH20-34 and XH20-30. In conclusion, this research achievement is dedicated to discovering and exploring the excellent tomato germplasm resources retained by the research group, laying a foundation for the next step of creating core parents and breeding new high-quality tomato varieties with characteristics unique to Xinjiang.

Areca palm leaf yellowing virus disease, caused by Areca palm velarivirus 1 (APV1), is a fatal disease for which no effective control measures currently exist. Breeding resistant or tolerant varieties is the key approach to addressing this issue, while the collection of superior germplasm resources is an essential foundation for breeding efforts. This study focused on three major affected areas in Hainan Province (Tunchang, Qionghai, and Wanning) and systematically conducted research activities including germplasm collection, phenotypic observation, pathogen detection, and long-term monitoring. The results revealed that among the 200 areca palm germplasm materials collected, 84 out of 100 resistant/susceptible materials did not show the presence of APV1, while 92 out of 100 susceptible materials tested positive for APV1. This finding confirmed a close association between APV1 infection and plant yellowing symptoms, and demonstrated that the screened resistant/tolerant materials are representative. Through continuous observation and correlation analysis, a significant negative correlation was found between tree age and resistance/tolerance to the disease. This study successfully identified a group of betel palm germplasm resources with resistance/tolerance traits, laying a crucial foundation for the development of disease-resistant varieties in future breeding programs.