Hainan Island possesses unique ecological conditions that nurture abundant wild tea resources. This study systematically investigated the distribution patterns and growth models of wild tea trees in Hainan through literature review and field surveys. Curvilinear regression analysis was employed to establish growth relationships among tree height (H), crown width (P), diameter at breast height (DBH, D), and basal diameter (d). Wild tea populations are distributed in Wuzhishan City, Baoting County, Qiongzhong County, Baisha County, Ledong County, and Lingshui County, spanning longitudes 108.85°E–109.91°E, latitudes 18.21°N–19.19°N, and elevations 357.0–1410.6 m. The population primarily occur in secondary forests and cultivated tea gardens, with significant canopy density fluctuations. The wild tea tree resources in the study area were mainly distributed in sheets, and 6915 wild tea trees were preliminarily investigated in 6 cities and counties, and the area with the largest number of wild tea trees was Wuzhishan, with a total of 4461 trees, accounting for 64.51% of the total. Wild tea tree diameter structure showed a normal distribution characteristic with grade II seedlings accounting for the main body (40.68%), followed by grade I seedlings (25.29%), and only 2.22% of the V–VI. large-diameter wild tea trees remaining, showing an obvious juvenile structure. Maximum crown width (11.5 m) and tree height (26.0 m) were recorded in Wuzhishan City, alongside the highest coefficients of variation for crown width (56.53%) and height (53.87%), with a crown-to-height ratio of 0.62. Optimal cubic regression models for growth relationships were: H=0.614+0.014C-0.258C²+2.13C³ (R²=0.488, h<700 m); H=1.949-0.001D+0.020D²+0.248D³ (R²=0.340, 700 m≤h<1300 m); D=-0.726+0.001d-0.024d²+1.026d³‌ (R²=0.887, h≥1300 m). The research would provide critical data for ecological monitoring in Hainan Tropical Rainforest National Park, tea germplasm conservation, and green certification of tea industries. It also would advance carbon sink management under China’s carbon neutrality goals and highlights the urgency for scientific conservation and sustainable utilization of wild tea resources to enhance biodiversity and regional socioecological resilience.

Intercropping within rubber plantations presents an effective strategy to counteract the financial challenges posed by sustained low prices of natural rubber and widespread cultivation losses. The success of the intercropping systems is critically dependent on understory light availability, which serves as a key driving factor. A thorough analysis of the variations in understory light conditions among different rubber clones and the underlying causes is essential for providing a theoretical basis for optimal clone selection and system design. This study investigated rubber plantations featuring various clones, tree ages, and planting patterns. The understory light intensity were measured and compared. Unmanned Aerial Vehicle LiDAR point clouds were used to extract key tree architecture parameters to determine the architectural drivers of light variability. Findings revealed significant differences in understory light intensity attributable to clone type, tree age, and planting pattern. Notably, the Reken 628 clone consistently provided significantly higher understory light levels across all ages and row orientations compared to other clones like CATAS 72059, and CATAS 73397. UAV-derived data confirmed that Reken 628 plantations exhibited larger inter-row gaps and significantly lower canopy closure. Architectural analysis further elucidated that Reken 628 was characterized by a taller stature, higher branching, a smaller crown length ratio, and a more compact, sparser crown structure with fewer, smaller-angled primary branches. This clone also displayed pronounced natural self-pruning, which collectively contributes to its low canopy closure. Conversely, CATAS 73397 features a wider crown, a higher crown length ratio, more numerous and wider-angled branches, and severe crown overlap, resulting in high canopy closure. In conclusion, considering its favorable tree architecture and the resultant superior light conditions, Reken 628 is identified as an excellent clone for intercropping systems. This research holds significant practical value for advancing the adoption and sustainable development of intercropping in rubber plantations.

The absence of standardized protocols for harvesting green betel nut fruits has led to significant inconsistencies in the quality of fresh produce. Therefore, this experiment used Hainan betel nuts as the test material, sampling every 30 days starting from 30 days after fruit setting, measuring the developmental dynamics of fruit phenotype and inclusions, exploring the development law of betel nut fruits, and determining the optimal harvesting period for green betel nuts. The fruit shape index showed a trend of first increasing and then decreasing, with a variation range of 1.69-1.87. Among them, when the fruit developed to 120 days (1.79)-150 days (1.61), the fruit shape index met the first-grade standard, presenting a long elliptical shape. The chlorophyll content was high at 120-180 days, and the fruit color was emerald green. The pulp hardness showed a trend of first increasing and then decreasing, with a variation range of 85.2-274.49 gf. The hardness at 120-150 days was lower than the average (197.34 gf), meeting the first-grade standard. The soluble sugar contents in both the pulp and kernel showed a trend of first increasing and then decreasing, with variation ranges of 1.23%-4.47% and 5.56%-7.12%, respectively. The soluble sugar contents in the pulp and kernel were high at 120-180 days. The arecoline contents in both the pulp and kernel showed a gradual decreasing trend, with variation ranges of 3.55%-0.19% and 3.42%-0.40%, respectively. The arecoline content in betel nut fruits reached a relatively high level at 120-180 days. After standardizing the data for several key nodes and performing Principal Component Analysis (PCA), the comprehensive score of the pulp and kernel was the highest (1.18) at approximately 150 days after flowering. Combining the variation laws of fruit phenotype and internal quality, the optimal harvesting period for green betel nuts is approximately 150 days after fruit setting.

Fruit quality is the key indicator to measure the commodity value of fruit, and the indicators such as single fruit weight, fruit shape and fruit determination degree (DD) are particularly crucial, which directly affect consumers' desire to buy. In addition, primary metabolites are indispensable substances in the process of plant growth and development, which are widely present in all plants, providing basal metabolites and energy support for plant growth, development and reproduction. Primary metabolites such as sugars, organic acids, amino acids and inositol are the key factors affecting fruit quality, and they are also important criteria for measuring fruit flavor and texture. With the improvement of consumers' living standards and the pursuit of healthy fruits, a large amount of data is needed to screen out Annona squamosa varieties with high nutritional value and high sugar. Yunnan's hot and dry valley climate provides an excellent environment for the fruit to thrive. In order to explore the differences in fruit quality and the composition and content of primary metabolites in the pulp of the four varieties of A. squamosa in the dry and hot river valley of Yunnan Province, the varieties with high nutritional value and high sugar were screened. Four varieties (AP, Damu, Fengli and Liulian) from the planting base of Yuanjiang County, Yuxi City, Yunnan Province were used as the test materials. Gas chromatography-mass spectrometry (GC-MS) was used to determine the composition and content of primary metabolites per unit weight of fresh fruit pulp, and the one-way analysis of variance (ANOVA), principal component analysis (PCA) and partial least squares discriminant analysis (PLS-DA) were used for comprehensive analysis and evaluation. Among the four cultivars in the dry-hot valley area of Yunnan, AP A. squamosa had the largest single fruit weight. The content of soluble solids (TSS) in Liulian A. squamosa was the highest. The fruit shape of the Damu A. squamosa is oval, and the other three varieties are oblong; The fruit DD of Fengli A. squamosa was the smallest, and there was no significant difference among the other three cultivars. A total of 43 primary metabolites were detected in the pulp of the four cultivars, including 9 amino acids, 13 organic acids, inositol and 20 soluble sugars. Further analysis of the contents of various primary metabolites in the pulp of the four varieties showed that the contents of sucrose, fructose, glucose, allulose, citric acid and malic acid were the main among the 43 primary metabolites. The contents of glucose, allulose, citric acid and malic acid in Liulian A. squamosa were significantly higher than those of other varieties, and the contents of sucrose and fructose in AP A. squamosa were significantly higher than those of other varieties. In addition, some primary metabolites had significant cultivarity specificity, among which leucine, acetamide acid, xylulose and threonate were only detected in AP A. squamosa. Trehalose is only detected in Liulian A. squamosa. Principal component analysis (PCA) showed that the variance contribution rate of PC1 was 48.3%, that of PC2 was 25.8%, and that of cumulative variance was 74.1%. Partial least squares discriminant analysis (PLS-DA) was used to screen 19 primary metabolites as the characteristic differential metabolites in VIP≥1, including 5 amino acids, serine, L-hydroxyproline, leucine, L-norvaline and L-glutamic acid. 2 organic acids, acetamide and 2-ketoglutarate; 7 soluble sugars, namely D-(+)-xylose, D-arabinose, hexapyranose, xylulose, L-threonose, L-(-)-fucose, sucrose, d-galactose, D-(+)-pinedisinose, maltose and D-(+)-cellobiose; and inositol. From the perspective of basic quality and primary metabolite level, the fruit TSS and primary metabolite content of Liulian A. squamosa were the highest, while the TSS of Fengli A. squamosa was moderate and the outer gauge was the most regular. Therefore, the two varieties can be promoted and planted as A. squamosa varieties with high nutritional value and high sugar in dry and hot river valleys.

Date palm, a member of the palm family, is dioecious with highly heterozygous genes and severe trait segregation. The propagation of its seedlings depends on asexual reproduction. Tissue culture technology is currently the main approach to realize the commercial production of date palm seedlings. However, the low germination rate of somatic embryos and the long period of seedling formation lead to difficulties in system construction and high tissue culture costs. Therefore, studying the physiological responses of date palm to adventitious bud induction regulated by hormones and optimizing the adventitious bud induction system are urgent tasks. Based on the previous screening of explant types of date palm, an orthogonal experimental design was used to optimize the induction of callus and embryogenic callus. By screening and proportioning the types and concentrations of plant growth regulators in the MS medium, adventitious buds were induced from somatic embryos. The germination rate of adventitious buds and the induction time of buds were statistically analyzed. Date palm adventitious buds obtained under different hormone levels were sampled, and the morphological change patterns of adventitious buds were observed. The change patterns of antioxidant enzyme activities (peroxidase, superoxide dismutase, glutathione reductase, catalase), hydrogen peroxide content, and other indicators in the samples were determined. The results indicated that the bud induction rate was P₈>P₆>P₅>P₄. The highest bud induction rate was achieved under the P₈ (MS+30 g/L sucrose+3 mg/L NAA+2 mg/L 6-BA+1 mg/L KT) treatment. The shortest bud induction time was under the P₆ (MS+30 g/L sucrose+2 mg/L NAA+3 mg/L 6-BA+1 mg/L KT) treatment. The highest activity of glutathione reductase was under the P₈ treatment. The coefficient of variation was the largest for the activity of glutathione reductase, and the range was the largest for the activity of superoxide dismutase. Principal component analysis revealed that the cumulative contribution rate of the first three principal components reached 94.614%. The eigenvalue of the first principal component was 2.365, with a contribution rate of 50.729%. In the first principal component, the activities of glutathione reductase, catalase, and peroxidase jointly affected, among which the eigenvalue of the activity of glutathione reductase was the largest at 0.821, mainly reflecting the influence of the activity of glutathione reductase on adventitious bud induction. The results of the study would provide a theoretical basis for optimizing the adventitious bud induction system and lay a technical foundation for achieving efficient and rapid propagation of date palm.

The study was aimed to explore the changes of basic nutrients, active substances and antioxidant activity of the Macadamia flowers in the bud swelling period, early flowering, and full-flowering stages, and provide the basis for its development and utilization. The changes of basic nutrients, active substance content and antioxidant activity of the Macadamia flowers at the bud swelling period, early flowering stage and full-flowering stage were systematically analyzed. The results showed that among the basic nutrients of the Macadamia flowers at three flowering stages, the water content showed a decreasing trend [the highest at the bud swelling period was (70.99±2.58)%]. Soluble protein was the highest (0.054±0.009)% in the bud swelling period. Crude fat increased first and then decreased [the highest was (2.20±0.021)% at early flowering]. The total ash content decreased first and then increased [the highest was (3.73±0.02)% at full-flowering stage]. The early flowering stage of total sugar was the highest (1.65±0.19)%. It contained 16 abundant amino acids (7 essential amino acids and 9 non-essential amino acids), and the total amino acid content decreased with the development of flowering period. The proportion of essential amino acids and E/N value were close to the international high-quality protein standard, showing good protein nutritional value. In the Macadamia flowers at different flowering stages, the contents of five major elements in the three flowering stages showed the order of K>Ca>P>Mg>Na, highlighting the advantages of high K and low Na. The content of K at full-flowering stage was 5.2 times that of banana, and the content of Ca was 5.0 times that of milk. However, as a food development, it is necessary to pay attention to the risk of excessive As, Cr and other harmful elements. A total of 22 (the bud swelling period), 14 (early flowering stage) and 20 (full-flowering stage) volatile components were identified, mainly hexanal and d-limonene, which together constituted its unique floral characteristics. The analysis of active components showed that the content of total polyphenols decreased significantly with the prolongation of flowering period, and the bud swelling period was (18.47±2.3)mg/g. The content of total flavonoids increased first and then decreased, and the content was the highest in the early flowering stage, reaching (8.09±0.63)mg/g. The antioxidant activity evaluation showed that the DPPH and ABTS free radical scavenging rates were the highest in the bud swelling period, which were (89.96±0.61)% and (99.50±0.22)%, respectively, and the antioxidant capacity was strong. In summary, the Macadamia flowers are rich in amino acids, minerals and active substances from the bud swelling period to the full-flowering stage, and have high antioxidant capacity, which provides a scientific basis for their subsequent development and utilization.

0, 60 and 120 kg/hm² MgO treatments (denoted by Mg0, Mg60, and Mg120, respectively) on a long-term wax gourd (Tiezhu No.2) magnesium (Mg) fertilizer gradient positioning experiment was conducted in 2022 and 2023 to investigate the physiological mechanism of Mg to improve the storage resistance of wax gourd fruits by regulating pectin metabolism by measuring indicators such as fruit hardness, weight loss rate, Mg content and morphology, pectin content and morphology, and pectin metabolic enzyme activity during fruit storage. Results showed that wax gourd yield increased by 8.5% to 16.9% after Mg fertilization, with the Mg60 treatment showing the greatest increase. Compared with the Mg0 treatment, the flesh hardness of the Mg60 treatment increased by an average of 12.9%, 11.7%, and 18.9% in the two years of 0, 30, and 60 d storage, while the Mg120 treatment showed a significant difference from the Mg0 only after 30 days of storage in 2022. Suitable Mg fertilization delayed the rise of the fruit storage weight loss rate. The fruit storage weight loss rate of Mg60 after 60 d was 34.4% and 35.1% lower than that of Mg0 and Mg120 treatment. Magnesium fertilization significantly increased fruit Mg content. Alcohol-soluble (Mg_Eth), water-soluble (Mg_Wat), and salt-soluble Mg (Mg_NaCl) were the main forms of Mg in the fruit. The content gradually increased with the prolongation of storage time. During fruit storage, the total pectin content gradually decreaseg. However, appropriate Mg fertilization (Mg60) delayed the decline in water-soluble (WSP), ion-bound (CSP), and covalently bound pectin (SSP) content, thereby maintaining the total pectin content. Suitable Mg fertilization (Mg60) inhibited the activity of polygalacturonase (PG) and β-galactosidase (β-Gal), thereby slowing down the degradation process of pectin. Concurrently, it increased pectin methylesterase (PME) activity and the content of free Mg²⁺ (MgEth and MgWat), enabling negatively charged pectin acid to bind with Mg²⁺, thereby increasing CSP and SSP. This slowed the rate of hardness decline and weight loss caused by pectin degradation during fruit storage. Comprehensively, suitable Mg (60 kg/hm²) fertilization can improve the storage resistance of wax gourd by regulating pectin metabolism, which is conducive to optimizing the Mg of wax gourd, improving the storage quality, and promoting the sustainable development of the industry.

Eotetranychus sexmaculatus Riley is an important pest mite on rubber trees, it causes damage to rubber leaves, causing localized chlorotic spots to spread to the entire leaf, resulting in severe yellowing. Severe infestations result in massive leaf drop, disrupting normal tapping operations and leading to yield losses. However, the changes in physiological and biochemical indicators of rubber tree leaves after mite damage, and the relationship with mite population density and infestation duration, remain unclear. This study aimed to reveal the effects of varying mite densities and infestation durations on physiological and biochemical traits in rubber tree leaves, and to elucidate the defense mechanisms of rubber trees, thereby providing a theoretical basis for mite monitoring and early warning and precise prevention and control of the mite. In this study, the effects of malondialdehyde (MDA), soluble sugars, soluble proteins and protective enzymes (SOD, POD, CAT) activities on the leaves of rubber trees with different infestation times were determined on the rubber potted seedlings of the same length of Thermo Scientific 7-33-97 rubber seedlings inoculated with different mite densities in the greenhouses. The two-way analysis of variance (ANOVA) was used to reveal the interaction between mite population density and infestation time. Regarding membrane lipid peroxidation damage, both mite population density and infestation duration significantly influenced MDA content, exhibiting an initial increase followed by a decrease as infestation time prolonged. MDA levels peaked at (73.91±1.89)nmol/g after 15 days of treatment with 40 mites per leaf, representing a 43.15% increase compared to the control. MDA levels began to decline to (65.09±0.29)nmol/g after 20 days. Both soluble sugar and soluble protein contents decreased with increasing mite density and duration of infestation. At a mite density of 40 mites/leaf with 20 days of continuous feeding, soluble sugar and soluble protein contents reached the lowest values at (34.42±1.43)mg/g and (17.74±0.63)mg/g, respectively, representing significant decreases of 44.20% and 45.30% compared to the control. In response to mite-induced oxidative stress, the protective enzyme activities (SOD, POD, CAT) in rubber tree leaves generally showed a significant upward trend during the early stages of mite infestation across different mite density and duration treatments. Enzyme activity peaks occurred earlier under high mite density treatments (30 mites/leaf and 40 mites/leaf). Specifically, SOD activity peaked at (13 086.92±613.39)mg/g after 5 days of 40 mites/leaf infestation, representing a 91.74% increase compared to the control. POD activity reached minor peaks at 10 days post-infestation in both 30 and 40 mites/leaf treatments (6293.13±80.75)U/(min·g) and (6655.54±51.44)U/(min·g), respectively, followed by a decline before rising again. CAT activity peaked at 10 days in the 40 mites/leaf treatment (165.77±0.41)µmoL/(min·g), representing a 62.74% increase compared to the control. Interaction analysis revealed that the interaction between mite density and damage duration significantly affected soluble sugar content (F=21.296, P<0.001), soluble protein (F=17.782, P<0.001), and significantly affected SOD (F=20.252, P<0.001), POD (F=9.821, P<0.001), and CAT (F=145.095, P<0.001) activities. Both the mite population density and the duration of damage inflicted by the E. sexmaculatus leaf mite can influence the physiological and biochemical indicators in rubber tree leaves, including malondialdehyde, soluble sugars, soluble proteins, and protective enzymes (SOD, POD, CAT). Furthermore, a significant interaction exists between mite population density and duration of damage (P<0.001). This confirms that stress intensity and duration do not act independently, but they jointly determine the physiological damage degree, nutritional status, and antioxidant defense efficiency of rubber tree leaves through a complex synergistic mechanism.

Camellia oleifera is an important woody oil crop in southern China. Due to its generally weak disease resistance, it is susceptible to various diseases, among which southern stem blight is one of the major threats to its production. This study systematically screened and analyzed the non-volatile metabolites produced by Trichoderma semiorbis FJ059 with antagonistic activity against Sclerotium rolfsii, the causal agent of southern blight in C. oleifera, and identified the potential antifungal components. The antagonistic effects of non-volatile metabolites produced in different solid-state fermentation media were compared using the growth rate method of mycelia. Results indicated that rice was the optimal substrate, yielding the highest antagonistic effect (99.61%). The solid-state fermentation products in rice media were extracted using different solvents. The ethyl acetate extract exhibited significantly higher inhibition activity than the aqueous extract. When the concentration was 500 μg/mL, the inhibition rates was 98.84% and 44.18%, respectively, indicating that the solvent selection play a vital role in the extraction of active compounds. LC-MS analysis identified several key active substances in the ethyl acetate extract, including nootkatone, caryophyllene oxide, farnesol, pyrrole-2-carboxylic acid, and trans-ferulic acid, all of which demonstrated significant antagonistic effects against S. rolfsii. Notably, the inhibition rate of 200 μg/mL nootkatone and 300 μg/mL caryophyllene oxide were both 100%, while 400 μg/mL farnesol, 400 μg/mL pyrrole-2-carboxylic acid, and 400 μg/mL trans-ferulic acid were 78.30%, 69.38% and 69.77%, respectively. The results indicated that medium-polarity or hydrophobic small molecules in the solid-state fermentation products of T. semiorbis FJ059 were potential antifungal components. The results indicated that the medium-polarity or hydrophobic small molecules detected in the ethyl acetate extract of solid-state fermented T. semiorbis FJ059 were closely associated with antifungal activity, suggesting that the ethyl acetate extract may enrich certain compounds with antifungal potential. The findings would provide new theoretical support and bioactive compound resources for the development of novel and efficient biocontrol agents against southern blight in C. oleifera.

The purpose of this study was to investigate the mechanism and efficacy of Lvnonglin ^®41 compound microbial fertilizer in mitigating black pepper continuous cropping obstacles from the perspectives of soil nutrients, microbial community structure and diversity, so as to provide technical strategies for the industrial cultivation of black pepper in Hainan. Field experiments were conducted on a plot with a history of severe black pepper Fusarium wilt. Four treatments were designed: water control (CK), Lvnonglin^® 41 compound microbial fertilizer (LNL41), compound microorganisms (CM), and bacterial fertilizer nutrient substrate (NS). The incidence of Fusarium wilt in the rhizosphere, plant growth and soil nutrients were measured. Using 16S rDNA sequencing technology, the differences in the occurrence of black pepper Fusarium wilt and the bacterial community structure in the rhizosphere soil under LNL41 application were explored. The results showed that compared with CK, all treatments exhibited certain effects, with the LNL41 treatment being the most effective. Soil nutrient indicators in the LNL41 and CM treatments were significantly higher than those in CK. The increases in chlorophyll content, spike length and 1000-grain weight under LNL41, CM and NS treatments reached 26.12%–67.87%, 6.20%–18.33% and 1.48%–6.44%, respectively. The incidence rates at different growth stages in the LNL41 treatment were 2.67%–15.67%, with control efficacies of 81.64%–90.06%. The Ace and Chao1 indices of rhizosphere soil bacteria increased by 12.82%–20.28% and 12.89%–18.78%, respectively, and the Shannon diversity index increased by 1.05%–3.53%, while the Simpson index showed no significant difference among treatments. At the order level, Chitinophagales, Rhizobiales and Burkholderiales were the dominant bacterial orders. At the genus level, Gaiella, P3OB 42, Lactobacillus, Pseudolabrys and Terrimonas were the dominant bacterial genera. The abundances of the common dominant genus Bacillus and Candidatus Omnitrophus were similar across treatments. Linear discriminant analysis (LEfSe) results indicated the presence of six indicator bacterial taxa in the LNL41 treatment. Ellin6067 and Tepidisphaera showed significant or highly significant positive correlations with soil pH, organic matter, available potassium, ammonium nitrogen and available phosphorus. Network analysis further revealed that the LNL41 treatment enhanced the complexity and stability of the soil bacterial co-occurrence network. Bugbase functional prediction demonstrated that the abundance of stress tolerant functional groups in the LNL41 treatment increased by 5.38 percentage points, while it decreased by 10.43 and 7.25 percentage points in the CM and NS treatments, respectively. LNL41 significantly improved the ratio of soil nutrients, thereby enhancing the structure and functional characteristics of the soil bacterial community, stimulating bacterial stress tolerance functions, promoting black pepper growth, and reducing the incidence of Fusarium wilt.