Tropical agriculture is critical to global food security and rural revitalization. However, its modernization is constrained by complex terrain, climatic variability and frequent disasters. Remote sensing, with its capacity for large-scale, real-time information acquisition, has emerged as a key enabler for smart and precision agriculture in tropical regions. This study established a framework for remote sensing research in China's tropical agriculture, proposing an integrated “space-air-ground” observation strategy and explaining the resolution-to-application matching mechanism, in which low-, medium-, and high-resolution observations are respectively suited for regional resource surveys, farmland growth monitoring, and field-scale phenotypic diagnostics. It reviewed progress in natural resource surveys, crop monitoring yield estimation, disaster assessment and ecological evaluation, analyzed challenges such as insufficient ground-truth data, limited model transferability, poor regional adaptability and low transformation efficiency; and proposes key innovation paths including coordinated sensing, multi-modal data fusion, intelligent modeling and digital twin-based forecasting. Finally, it outlined future directions focusing on system integration, intelligent perception, and global collaboration. The findings would provide theoretical and technical support for enhancing remote sensing applications in tropical agriculture.

In this study, three pitaya varieties, Spineless Yellow Dragon, Fuguihong, and Jindu No. 1, were selected as rootstocks. Through systematic observation and analysis of key indicators such as the growth potential of cuttings, grafting survival rate, fruit traits and quality, the most suitable rootstock variety was determined. Combined with the environmental conditions in Hainan, corresponding cultivation and management suggestions were put forward, aiming to provide solid technical support for the development of the pitahaya industry. Rootstock Fuguihong performed the best in the comprehensive survival rate of cuttings and grafting. The promoting effect of growth potential on pitahaya was significantly better than that of other rootstocks. Therefore, Fuguihong was determined as the optimal rootstock. Meanwhile, different rootstocks had a significant impact on the fruit traits of pitahaya (including 10 traits such as single fruit weight, peel weight, pulp weight, soluble solids, and total sugar). During the cultivation and management process, the suitable cultivation conditions for pitahaya in Hainan were summarized. Before cultivation, the field should be prepared and ridged first. 17 tons/667 m² of decomposed sheep manure and earthworm manure in a ratio of 3∶1 were spread over the whole garden. After rotary tillage and deep plowing, ridges with a width of 1m, a height of 25–30 cm, a row spacing of 2 m, and a ditch depth of 30 cm were built. Appropriate branches were selected as rootstocks. After treatment, they were planted at a density of 7 plants per meter in early September. In the first and second ten days of October, the “two-bud side flat grafting method” was used for grafting, and paper bags were put on. At the same time, a “丰” -shaped scaffold was built. Field management included soil covering or planting white clover and laying ground cloth, adjusting water and fertilizer according to the growth status, bending branches and leaving buds when the main branches exceeded the scaffold by 1 m, and closely monitoring common diseases such as sooty mold to ensure the orderly progress of all work, thus promoting the growth and development of pitahaya. This study would lay an important technical foundation for the vigorous development of the pitahaya industry in Hainan, effectively promote the progress of the domestic pitahaya cultivation industry, and significantly enhance its market competitiveness.

Miniature inverted-repeat transposable elements (MITEs), as active mobile elements in eukaryotic genomes, provide novel molecular markers for germplasm genetic diversity analysis through the insertion polymorphisms. This study systematically identified hAT family MITE transposons in pitaya using bioinformatics approaches based on the whole-genome data of the Guanhua Bai cultivar. A total of 2350 candidate elements with complete terminal inverted repeats (TIRs) and target site duplications (TSDs) were screened, with an average of 213 elements per chromosome pair. Through sequence specificity and polymorphism analysis, 110 highly divergent loci (10 per chromosome pair) were selected for primer design, ultimately yielding 41 stable polymorphic hAT-MITE markers after PCR validation. Genome-wide scanning of 48 pitaya germplasms using the 41 primer pairs detected 81 polymorphic loci (polymorphism rate: 97.59%) via agarose gel electrophoresis. UPGMA cluster analysis revealed substantial genetic variation and diversity among the 48 accessions, with genetic similarity coefficients ranging from 0.57 to 0.91. At a genetic similarity threshold of 0.63, the germplasm resources were categorized into four genetically distinct groups. A digital fingerprinting system covering all germplasm resources was constructed using four core primer pairs (HU-MIT-02/06/26/75) based on the primer-band pattern combination method, achieving 100% cultivar identification accuracy. This study established the first hAT-MITE molecular marker system for pitaya, providing an efficient toolkit including a marker library and standardized identification protocols for precise germplasm classification, cultivar identification and varieties property protection of pitaya. The advancements is of significant application value for intellectual property protection in the pitaya seed industry.

It is necessary to establish a sensitive, selective, efficient and accurate method for the simultaneous detection of multiple antibiotic residues in soil. In this study, the method of solid phase extraction-high performance liquid chromatography-tandem mass spectrometry (LC-MS/MS) for the determination of 20 antibiotics simultaneously in soil was established by optimizing the extraction conditions (extractant type, extraction method, shading and overnight) and the purification conditions (cartridge type). Under the optimized analysis conditions, the target antibiotics showed good linearity in the linear range of 0.10-100.00 μg/kg, with R² ranging from 0.9951-0.9999. The recovery ratio ranged from 62%-116%, the relative standard deviation was 0.9%-16.8%, the limit of detection was 0.01-0.50 μg/kg, and the limit of quantification was 0.04-2.00 μg/kg. The method was applied for the detection of antibiotic residues in soil samples collected from greenhouse vegetable bases in Wuqing district, Tianjin, China. It showed that 4 classes of antibiotics were detected in the soil, and up to 16 of target antibiotics could be detected simultaneously. The total residual concentration of antibiotics in the soil varied from 2.52-142.00 μg/kg. The highest concentration of individual antibiotic was 105.00 μg/kg (oxytetracycline). The method established in the study is aim to provide reference for the formulation of the standard for the simultaneous detection of multiple antibiotic residues in soil and provide methodological basis for the prevention and control of emerging contaminants.

Lignin serves a crucial defensive function in cassava's resistance to harmful organisms. Among the genes involved in lignin biosynthesis, shikimate hydroxycinnamoyl transferase (HCT) and caffeoyl coenzyme A-O-methyltransferase (CCoAOMT) are of particular importance. Yet, their specific roles in cassava's resistance to the insect pest P. marginatus remain to be fully elucidated. To elucidate the anti-insect defense mechanisms of cassava against P. marginatus, we conducted comparative studies using insect-resistant cultivar C1115 and susceptible cultivar KU50. Life table analysis revealed significant cultivar-dependent effects on pest developmental biology. Specifically, C1115-fed females exhibited significantly prolonged developmental duration (38.50 days in C1115 vs. 28.86 days in KU50), significantly reduced fecundity (221 eggs in C1115 female vs. 331 eggs in KU50 female), and significantly shortened adult longevity (4.30 days in C1115 vs. 8.83 days in KU50). Notably, population growth parameters demonstrated significant comprehensive suppression in C1115 cohorts: net reproductive rate (R₀=224.13 in C1115 vs. 330.67 in KU50), intrinsic growth rate (r_m=0.10 d^‒1 in C1115 vs. 0.12 d^‒1 in KU50), and finite growth rate (λ=1.11 d^‒1 in C1115 vs. 1.12 d^‒1 in KU50). Furthermore, extended generation time (T=50.25 in C1115 vs. 49.98 days in KU50) and doubling time (Dt=6.44 in C1115 vs. 5.97 days in KU50) were observed, indicating multilevel inhibition of pest population dynamics by C1115. Molecular characterization showed progressive downregulation of lignin biosynthesis genes HCT and CCoAOMT post-infestation in C1115. Although both cultivars exhibited suppression patterns, C1115 maintained significantly lower expression levels (52.99%, 66.81% of KU50) and enzymatic activities (74.42%, 73.91% of KU50) across timepoints. Using Spearman correlation analysis, it was found that both HCT and CCoAOMT gene expression levels and the activity of their encoded enzymes were negatively correlated with cassava resistance to P. marginatus. This suggests that the downregulation of these two genes may affect lignin accumulation in cassava leaves and the level of insect resistance defense responses. This study has laid a solid preliminary work foundation for in-depth analysis of the molecular mechanisms by which lignin regulates cassava's defense responses against P. marginatus

The fruits of Qiongdong No. 9 Camellia oleifera at five developmental stages were taken as the experimental materials to ascertain the basic characteristics of the growth and development in Hainan and the changes in the content of antioxidant active substances. The morphological characteristics were observed, the crude fat and six main active ingredient contents of the seeds at different developmental stages were measured, and four antioxidant activity indicators of the seeds at different developmental stages were detected. The results demonstrated that the growth changes of each part of the fruit generally followed a logistic curve, presenting a slow increase in the initial stage, a rapid growth in the middle stage, and eventual stabilization. During the whole growth period, changes in crude fat content continued to accumulate, with S₃-S₅ being the period of rapid oil accumulation; the changing trends of the contents of flavonoids, total polysaccharides, vitamin E, ABTS radical scavenging ability and total antioxidant activity (FRAP) in seed kernels were consistent, experiencing a process of rapid decrease-significant increase-slow decrease. The content of carotenoids and the ability to scavenge hydroxyl radicals showed a significant increasing trend at all stages. The content of total phenols, total saponins, and total antioxidant activity (DPPH) showed a gradually decreasing trend. Through Pearson correlation analysis, the content of six active ingredients was significantly correlated with four antioxidant capacity indicators to varying degrees, and each ingredient had a different degree of response to different antioxidant capacities. S₁–S₃ were the rapid swelling stages of the fruit, accompanied by significant fluctuations in the content of active ingredients. S₃–S₄ were the key stages of substance transformation, and S₄–S₅ were the steady-state accumulation stages of contents; In the early stages of fruit development (S₁–S₃), water-soluble antioxidant components such as phenols, saponins, and polysaccharides dominated, while in the middle and late stages (S₃–S₅), they shifted towards lipid soluble components (carotenoids) and lipids. This competitive process was an important reason for the decrease in the content of the main active components. This research revealed the growth and development characteristics of C. oleifera fruits in tropical areas, which would have theoretical reference value for formulating corresponding cultivation and management measures for quality breeding purposes.

Guangdong and Guangxi are the major production regions of pitaya and the common area for pitaya canker. Understanding the genetic diversity of Neoscytalidium dimidiatum is of great significance for the disease prevention and control. This research focused on four geographical population of N. dimidiatum mainly collected from Guangxi and Guangdong. To obtain the genetic fingerprints of N. dimidiatum, the isolates were amplified using ISSR genetic molecular markers and further analyzed the genetic diversity. The tested N. dimidiatum isolates were amplified with eight ISSR primers, resulting in 203 bands and the percentage of polymorphic sites was 31.7%, with the genetic similarity coefficient for any two germplasm resources ranged from 0.7619-1.0000. When the genetic similarity coefficient was 0.90 on the UPGMA cluster, all isolates could be divided into three groups, but the genetic groups were not closely related to the geographical distribution. The results of principal component analysis indicated considerable overlap between the four geographical groups and there were no relatively independent geographical poputation. This study proved that there existed lower level of genetic polymorphism in the isolates and there was frequent exchange of inoculum source between different places. The study would provide the scientific basis for researching the genetic architecture and pathogen surveillance of pitaya canker pathogen N. dimidiatum.

This study aimed to identify the key factors influencing vegetation changes on Hainan Island under Typhoon Yagi, determine the disaster thresholds, and provide scientific support for typhoon disaster prediction, assessment, and mitigation. Using the GEE platform, Sentinel-2 NDVI data from August 19 to September 18, 2024, covering the period before and after Typhoon Yagi landfall, were analyzed in conjunction with topographic and meteorological variables (such as typhoon path, maximum wind speed, minimum pressure, and precipitation). An XGBoost model was applied to predict post-typhoon NDVI changes, and SHAP analysis was used to explore the nonlinear effects of meteorological factors. The XGBoost model yielded a coefficient of determination (R²) of 0.75 and a root mean square error (RMSE) of 0.12, indicating a high prediction accuracy for post-typhoon NDVI changes. Feature importance analysis within the XGBoost model revealed that pre-typhoon NDVI, typhoon distance, and maximum wind speed were the primary influencing factors, while slope and aspect had a weaker effect. Further SHAP analysis confirmed that typhoon distance and maximum wind speed were the key meteorological factors driving NDVI changes. When the typhoon distance was less than 76.4 km, NDVI showed a significant decline, while NDVI changes intensified when the maximum wind speed exceeded 29.3 m/s, highlighting the crucial role of strong winds in vegetation damage. Regions within 76.4 km (approximately within the 11th wind radius) of the typhoon's path and with maximum wind speeds greater than 29.3 m/s experienced severe vegetation damage. It is recommended that the high-risk areas be prioritized in typhoon warnings and pre-disaster defense measures.

The study prepared slow-release fertilizers with different ratios of zeolite and nano-zeolite and compared them with conventional urea fertilizers to study the effect of zeolite and nano-zeolite as urea carriers on soil nutrient leaching, including nutrient release patterns, leaching characteristics, and impacts on soil nutrient content. A soil column leaching experiment was conducted with seven treatments, conventional urea (CK) and slow-release fertilizers with different ratios of zeolite (ZU₁, ZU₂, ZU₃) and nano-zeolite (nZU₁, nZU₂, nZU₃). The study analyzed the dynamic changes and cumulative leaching amounts of ammonium nitrogen, nitrate nitrogen, total nitrogen, and total phosphorus in the leachate and measured the soil nutrient content after leaching. Zeolite and nano-zeolite-based slow-release fertilizers significantly prolonged fertilizer effectiveness and reduced the concentration of ammonium nitrogen, nitrate nitrogen, total nitrogen, and total phosphorus in the leachate (P<0.05). Treatments with 50% zeolite (ZU₃) and 50% nano-zeolite (nZU₃) were the most effective in reducing nutrient leaching. Specifically, ZU3 reduced ammonium nitrogen, nitrate nitrogen, total nitrogen, and total phosphorus in the leachate by 7.19%, 6.54%, 14.51% and 9.72%, respectively, while nZU₃ reduced them by 7.20%, 6.91%, 12.84% and 6.36%, respectively. The slow-release fertilizers also significantly increased soil nitrogen content, with total nitrogen in ZU₃ and nZU₃-treated soils increasing by 14.88% and 19.83% compared to the control. From the perspective of nutrient release patterns, it was observed that zeolite and nano-zeolite slow-release fertilizers exhibited a lower release rate in the early stages of the experiment. This is attributed to the strong adsorption properties of zeolite and nano-zeolite, which can effectively slow down the release of urea. The release peak of the fertilizers was delayed to 6–8 days, and the release became more steady in the later stages of leaching. This pattern suggests that the application of zeolite and nano-zeolite can effectively reduce the risk of nutrient loss due to leaching, thereby improving the utilization efficiency of fertilizers. Furthermore, the comparison between zeolite-based and nano-zeolite-based slow-release fertilizers revealed that the differences in reducing the leaching of ammonium nitrogen, total nitrogen, and total phosphorus were not obvious, but both of them had significantly better performance than conventional urea in terms of reducing nutrient leaching (P<0.05). In summary, the use of zeolite and nano-zeolite as urea carriers in slow-release fertilizers showed to be an effective strategy for delaying nutrient release, reducing nitrogen and phosphorus leaching, and enhancing soil nutrient content. The optimal results were achieved with a 50% zeolite and 50% nano-zeolite ratio, indicating a promising application potential in agricultural practices. This approach not only contributes to the sustainable management of soil fertility but also offers a potential solution for reducing the environmental impact associated with excessive fertilizer use.

Rubber plantations represent one of the most widespread planted forest ecosystems in tropical regions, playing a significant role in regional carbon cycles. Global climate change has led to increasingly frequent Compound Drought-hot Events (CDHEs), posing severe challenges to rubber plantation ecosystem functions. This study focuses on rubber plantations in Hainan Island, China. Utilizing standardized soil moisture and land surface temperature indices, we constructed a Compound Drought-Hot Index (CDHI) based on Copula functions to analyze the spatiotemporal dynamics of CDHEs from 2001 to 2020, validated against historical typical drought and hot events in Hainan. Using Gross Primary Productivity (GPP) as an evaluation metric, Copula-based conditional probabilities were applied to quantitatively assess GPP loss risks under different drought-hot scenarios and evaluate compound effects. Key findings include: (1) The developed CDHI accurately identified severe CDHEs during 2001—2020, with 2005 and 2020 being the most extreme years. (2) Across all intensity levels (mild, moderate, severe), CDHEs caused significantly higher probabilities of GPP loss in rubber plantations compared to isolated drought or hot events (P<0.001), confirming the synergistic amplification effect of compound events. (3) GPP loss risks exhibited distinct spatial heterogeneity influenced by regional topography-climate interactions, with northwestern rubber plantation areas showing consistently higher vulnerability across all scenarios. (4) CDHE impacts demonstrated marked seasonal differences, being substantially greater during the dry season (particularly April—May) than the rainy season, coinciding with critical phenological stages of rubber trees and forming sensitive windows of environmental stress. This study reveals the spatiotemporal differentiation of CDHE impacts on rubber plantation GPP, providing scientific foundations for regional climate-resilient management strategies and sustainable rubber plantation practices. It also offers methodological references for studying extreme climate responses in other tropical planted forest ecosystems.