The growth of fruit trees inevitably casts a certain degree of shade on the grass plants in the orchard. Therefore, the selected grass species usually need to possess a certain level of shade tolerance. This study investigated the shade tolerance of two prevalent ground cover species in southern China, Alysicarpus bupleurifolius (L.) DC. and Alysicarpus vaginalis (L.) DC.. Different shading treatments were set with full light as the control (CK). Growth and physiological indices of the two species were measured, and a comprehensive evaluation of the shade tolerance was conducted to assess the potential as ground cover species in orchards. Findings indicated that as shading intensified, both species exhibited an overall increase in the leaf width, leaf area plant height and the proportion of aboveground biomass, while the stem diameter and total biomass showed a downward trend. Compared with A. vaginalis, the leaf area of A. bupleurifolius increased faster after 21 days of shading treatment, and the total biomass decreased less after 42 days of shading treatment. After shading treatment, the PSII maximum photochemical quantum yield (Fv/Fm) of the two plants was higher than 0.80, and shading did not cause serious damage to the photosynthetic system of the two plants. The relative electrical conductivity and malondialdehyde content of the leaves of the two species generally rose with increased shading intensity, whereas the peroxidase activity (POD) activity under shading conditions displayed distinct patterns. With the increase of shading intensity, the POD activity of A. bupleurifolius increased first and then decreased, while that of A. vaginalis showed a downward trend. Principal Component Analysis (PCA) was performed to reduce the dimensionality of 14 shade tolerance indices into two principal components, which cumulatively accounted for 88.66% of the total variance. In the first principal component (PC1), the contribution rate of malondialdehyde (MDA) content was the highest. In the second principal component (PC2), the contribution rate of leaf relative conductivity was the highest. The results of comprehensive evaluation of shade tolerance by membership function method showed that A. bupleurifolius was higher than that of A. vaginalis under identical shading conditions, indicating that the shade tolerance of A. bupleurifolius was higher than that of A. vaginalis. In summary, both A. bupleurifolius and A. vaginalis exhibit noticeable shade tolerance, with A. bupleurifolius outperforming A. vaginalis, thereby affirming the potential as viable orchard ground cover species.

Cowpea aphids, two-spotted spider mites, and bean thrips are main pests during the cowpea seedling stage, severely impacting the growth and development of cowpea plants. To evaluate the safety and control efficacy of four seed coating treatments, 10% clothianidin flowable concentrate for seed treatment FS, 30% thiamethoxan FS, 600 g/L imidacloprid flowable concentrate for seed coating FSC and 8% fipronil FSC on three common pests during the cowpea seedling stage, this study conducted indoor pot experiments with insect infestations. The experiments aimed to evaluate the impact of the four seed coatings on cowpea emergence and the effectiveness in controlling cowpea aphids, two-spotted spider mites, and bean thrips. The results indicated that the germination rate of cowpea treated with 10% clothianidin FS, 30% thiamethoxan FS, 600 g/L imidacloprid FSC, and 8% fipronil FSC was 95.83%, 91.67%, 95.83% and 95.83%, respectively. The rate was slightly lower than that of the control (100%), but did not significantly affect crop growth. The findings revealed that 30% thiamethoxan FS exhibited the highest control efficacy against both cowpea aphids and bean thrips. Specifically, the control efficacy against cowpea aphids at 3, 7 and 14 days post-infestation was 65.04%, 81.10% and 72.35%, respectively. For bean thrips, the control efficacy at the same time points was 15.41%, 58.61% and 54.89%, respectively. As the infestation period progressed, the effectiveness of the seed coating treatments in controlling cowpea aphids and bean thrips gradually decreased. None of the four seed coating treatments demonstrated significant control efficacy against two-spotted spider mites. This research provides technical support for pest management during the seedling stage of cowpea production.

Bok choy (Brassica campestris ssp. chinensis) is an important vegetable crop native to China and is also one of the leafy vegetables favored by people in Hainan. The high temperature and intense sunlight in Hainan’s summer greatly affect the normal growth and development of bok choy, reducing its yield and quality. At present, research on the growth of bok choy under abiotic stress is mostly focused on heat tolerance, while study on the response of bok choy to strong light stress is relatively scarce. To investigate the molecular regulatory mechanisms of bok choy in response to strong light, this study used the variety ‘Aijiao Huang’ as the research object. We compared and analyzed the physiological indicators, photosynthetic characteristics, and expression levels of response genes in the leaves of bok choy under normal light [300 μmol/(m²·s)] and strong light [1500 μmol/(m²·s)]. Under strong light, dry weight of bok choy significantly increased, and the R/S ratio gradually increased from day 0 to day 10, followed by a significant decrease on day 15. The chlorophyll content significantly decreased in the later stages. Pn, Tr, and Gs significantly increased on day 5 under strong light, and then gradually decreased, while Ci remained relatively stable. Using RNA-seq technology for transcriptome sequencing, a total of 2324 differentially expressed genes (DEGs) were identified. GO and KEGG enrichment analyses revealed 14 DEGs related to photosynthesis and photoprotection mechanisms, and 6 DEGs associated with antioxidant enzyme activity. 8 DEGs were selected for qRT-PCR validation, which were consistent with the transcriptome sequencing results, confirming the reliability of the transcriptome analysis. Strong light had a certain impact on the antioxidant enzyme activity of bok choy. During days 0-5, the activity of SOD, POD, and CAT was induced to increase, while from days 5-15, the activity of SOD and POD gradually decreased, and CAT showed an upward trend. In summary, bok choy may rapidly respond to photosynthesis-related mechanisms and regulate antioxidant enzyme activity under strong light conditions, thereby alleviating the inhibitory effects of strong light on growth and enhancing the seedlings adaptability to strong light.

The study investigated the effects of different exogenous hormones on somatic embryo maturation to improve the maturation efficiency of somatic embryos and increase the yield of normal mature embryos and embryo-derived plantlets in the rubber tree variety Yunyan 73-477. Primary somatic embryos from anthers at different developmental stages were cultured on media supplemented with various types and concentrations of exogenous hormones. The maturation rates, normal mature embryo rates, and plantlet conversion rates were comprehensively analyzed to compare maturation efficiencies and optimize hormone combinations for different developmental stages. The maturation efficiency increased with embryo developmental progression, with cotyledon embryos showing optimal results. The maturation rates exceeded 50% [range: 50.74%-74.83%, mean: (66.25±6.98)%]. Most mature embryos displayed bipolar structure and could normally germinate into complete plantlets, with normal mature embryo rates ranging from 35.0%-59.96% [mean: (47.80±6.89)%] and plantlet conversion rates ranging from 15.62%-49.17% [mean: (26.67±8.99)%]. Torpedo-shaped embryos showed intermediate performance, while heart-shaped embryos performed the poorest, both with maturation rates below 31% [means: (30.05±12.68)% and (29.33±10.93)%, respectively]. Most mature embryos from the stages were malformed (leaf-like or callus-like) and failed to develop into complete plantlets. The normal mature embryo rates were only (15.64±7.01)% and (5.46±4.28)%, respectively, 32.16% and 42.34% lower than cotyledon embryos. Plantlet conversion rates were (7.22±3.41)% and (0.83±0.80)%, merely 0.27-fold and 0.03-fold of cotyledon embryos. Optimal exogenous hormones varied with developmental stages: heart-shaped embryos required 6-BA 0.5 mg/L+NAA 0.15 mg/L+KT 0.25 mg/L, torpedo-shaped embryos needed ABA 0.4 mg/L+GA₃ 0.5 mg/L+6-BA 2.0 mg/L+NAA 0.15 mg/L, and cotyledon embryos performed best with ABA 0.1 mg/L+GA₃ 1.0 mg/L+6-BA 1.5 mg/L+NAA 0.2 mg/L.

The response of nitrogen, phosphorus and potassium nutrient accumulation, yield and output value of flue-cured tobacco in multi-planting area of tobacco-rice to the nitrogen application and basal-topdressing ratio was studied to provide a theoretical basis for the development of fertilizer application strategies for paddy-tobacco. Cultivar Yunyan 87 was used and three nitrogen application treatments (150 kg/hm², 165 kg/hm² and 180 kg/hm²) and two basal-topdressing ratio of nitrogen treatments (3∶7 and 5∶5) were set up. The effects of nitrogen application and basal-topdressing ratio on the accumulation and distribution of nitrogen, phosphorus and potassium nutrients, also on yield, output value and fertilizer utilization of paddy-tobacco, and the contribution rate of nitrogen application and basal-topdressing ratio and the interaction to the accumulation of nitrogen, phosphorus and potassium were analysed using the effect value (). The results showed that nitrogen, phosphorus and potassium nutrients accumulated by flue-cured tobacco were mainly allocated to tobacco leaves, and the proportion allocated to tobacco leaves decreased with the growth of flue-cured tobacco. With the increase of nitrogen application, nitrogen accumulation and tobacco yield and output value of flue-cured tobacco increased, meanwhile reducing the proportion of base fertilizer nitrogen could significantly increase the nitrogen accumulation of the tobacco plant and yield and output value of tobacco leaf, also significantly increase the utilization rate of nitrogen fertilizer and the partial productivity and the partial production benefit of nitrogen, phosphorus and potassium fertilizers. On average, nitrogen application and basal-topdressing ratio and the interactions contributed 42.89%, 29.63% and 27.47% to nitrogen accumulation of flue-cured tobacco, and 38.62%, 24.12% and 37.25% to phosphorus accumulation, and 41.22%, 21.24% and 37.54% to potassium accumulation, and 62.13%, 6.34% and 31.53% to yield, and 47.30%, 14.74% and 37.95% to output. Throughout the reproductive period, nitrogen accumulation was relatively high in the nitrogen treatments of 180 kg/hm² and the 3∶7 basal-topdressing N ratio. In the rosette stage and dome stage, the accumulation of phosphorus and potassium was relatively high in the nitrogen treatments of 180 kg/hm² and 3∶7 basal-topdressing N ratio. The highest yield and output value were achieved in the nitrogen treatments of 180 kg/hm² and 3∶7 basal-topdressing N ratio. Therefore, in the multi-planting area of tobacco-rice, the nitrogen application has the greatest influence on the accumulation of nitrogen, phosphorus and potassium nutrients in flue-cured tobacco, and the reduction of the proportion of base fertilizer nitrogen from 50% to 30% can increase the accumulation of nitrogen of tobacco leaf, which is conducive to the improvement of the yield and output value of tobacco leaf and the utilization rate of nitrogen fertilizer.

The three-year-old Phyllostachys prominens in the coastal sandy land of Dongshan was used to determine the contents of chlorophyll (Chl), soluble protein (SP), soluble sugar (SS), proline (Pro), and malondialdehyde (MDA) in the leaves in different seasons, and to explore the difference of physiological indexes of bamboo leaves under different seasonal environmental conditions, and analyze its adaptation in different seasonal environments in coastal sandy land, provide theoretical basis for constructing a more complete, abundant and economically valuable coastal shelter forest ecosystem. The chlorophyll a (Chla) and chlorophyll b (Chlb) had the same seasonal variation trend, and reached the highest content in summer. The total chlorophyll content in summer was 24.54%, 11.39% and 21.2% higher than that in autumn, winter and spring, respectively. The content of SP was the highest in winter and the lowest in summer. The content of SP in winter was 50.65%, 131.42% and 18.52% higher than that in spring, summer and autumn, respectively. The content of SS in summer was significantly higher than that in other seasons, which was 269.83%, 112.65% and 99.93% higher than that in spring, autumn and winter, respectively. The content of MDA decreased gradually from autumn to summer, and the difference between seasons was significant. The content of Pro was the highest in summer, which was 18.37%, 44.06% and 23.13% higher than that in spring, autumn and winter, respectively. Temperature and precipitation had significant effects on soluble sugar, soluble protein and malondialdehyde content. In the coastal area of Dongshan, during the same period of temperature and precipitation, compared with the highest and lowest periods of temperature (precipitation), the content of soluble sugar increased by 99.93%, the content of soluble protein decreased by 56.79%, and the content of malondialdehyde decreased by 52.72%. In summary, P. prominens ensures the smooth progress of photosynthesis by regulating chlorophyll content, and adapts to seasonal changes by regulating the content of osmotic substances. Photosynthesis and osmotic adjustment system are the key mechanisms for P. prominens to adapt to adversity environment.

An antimicrobial peptide (SAMP) derived from Microcitrus australasica can not only reduce the concentration of Candidatus Liberibacter asiaticus (CLas) in the infected trees and reduce the symptoms of the diseased trees, but also induce innate immunity and prevent the infection of Huanglongbing in healthy trees that are not infected with Huanglongbing. MaSAMP was analyzed by functional structure, subcellular localization and phylogeny. The results showed that the open reading frame (ORF) of MaSAMP was 201 bp in length, encoding 67 amino acids. The molecular weight of the corresponding protein was 7.59959 kDa, the theoretical isoelectric point was 5.38, and the instability index (Instability index (II)) was 33.22. The aliphatic index was 87.16%, and the grand average of hydropathicity was -0.09, indicating that the protein was a hydrophilic one. The protein contained one Dabb domain and was predominantly structured by α-helices and random coils. In terms of evolution, MaSAMP was phylogenetically close to the stress-response A/B barrel domain-containing protein CISIN_1g033887mg from Citrus sinensis and the A/B barrel domain protein HS1 from Citrus×clementina, with protein similarity of 97.01% and 91.04%, respectively. Subcellular localization results indicated that MaSAMP was localized in chloroplasts. Furthermore, through homologous recombination, a pCAMBIA1300-35S::MaSAMP-EGFP overexpression vector fused with an EGFP fluorescent tag was successfully constructed, and transgenic citrus plants were obtained using agrobacterium-mediated in planta transformation technology. This study would provide a material basis for subsequent research on the biological functions of MaSAMP.

Rubber tree is one of the “Three Trees” of Hainan, and it is cultivated in several cities and counties across the island. Rubber tree powdery mildew is a typical airborne fungal disease that occurs annually, severely affecting rubber yield and tree health. This study analyzed the potential airborne dispersal pathways of rubber tree powdery mildew spores from February 1, 2021, to March 31, 2023, with a focus on Baoting as the starting point for spore diffusion. Using the Lagrangian Hybrid Single-Particle Trajectory (HYSPLIT) model, airflow trajectories at various altitudes were simulated, and trajectory clustering analysis was performed with TrajStat software and the MeteoInfoMap platform to identify representative air mass transport paths. Results indicated that Baoting was the earliest outbreak area of rubber tree powdery mildew in Hainan, where airflows predominantly spreaded southwestward and northwestward, covering neighboring regions such as Sanya, Ledong and Wuzhishan. This suggests that spore dispersal via airflow may accelerate disease progression in the areas. Additionally, the study found that the spatiotemporal dynamics of spore spread primarily occurred from January to April each year, coinciding with the spring temperature and humidity conditions in Hainan and the phenological stages of rubber trees. The average budburst and disease onset times in Baoting preceded those in other regions, further the importance of Baoting as an early monitoring and warning site for powdery mildew in rubber trees. In conclusion, this study reveals the regional spatiotemporal transmission patterns of powdery mildew spores in Hainan island through the simulation and analysis of airborne spore dispersal from Baoting. The findings would provide scientific evidence and technical support for the formulation of targeted regional control measures, contributing to the effective management of powdery mildew and the stable development of Hainan’s rubber industry.

The axillary buds, which are embedded in the stem of Phalaenopsis and lurked at the base of leaves, can germinate and elongate to form pedicels under suitable conditions. The microscopic observation of the differentiation process is one of the important research contents to understand the flower development process and influencing factors of Phalaenopsis. In order to establish a paraffin section method for two different tissues with soft and hard connection, the stem segment with axillary bud was used as the test material. The preparation steps, such as fixed time, softening liquid concentration and softening time, dehydration, etc., which mainly affect the paraffin section effect, were optimized. The results showed that vacuuming the fixative and extending the fixative time to 48 h or more were conducive to the full penetration of the fixative, and the fixative effect was the best. Using 10%, 12% hydrofluoric acid solution to soften for 12, 15 days and vacuuming for 30 min during softening could greatly reduce the brittleness and hardness of stem tissues with high lignification degree, meet the soft and hard requirements of sections, and effectively solve the problem of tissue separation and fragmentation caused by uneven softening. Dehydration treatment was set up with 7 step by step dehydration gradients from 30% to 100% ethanol, and the gradual replacement steps of anhydrous ethanol to xylene were added, which could avoid the shrinkage and deformation of tissue materials of Phalaenopsis and ensure the integrity of tissue morphology. The optimized preparation method avoids the problems such as incomplete softening, separation of tissues from paraffin wax, crumpling and crushing of wax bands, and cavity of sections caused by conventional preparation of the stem segment of the axillary bud of Phalaenopsis girdle, etc. The overall structure of the obtained sections tends to be complete, the staining is uniform and bright, and the tissue cells in each part are obviously colored. Young bud tissue and lignified stem tissue can be clearly distinguished. In this study, a set of paraffin section preparation method was developed which could be applied to the stem segment of Phalaenopsis axillary bud, a soft and hard tissue material, and would provide a technical basis for further study on the differentiation process of latent axillary bud germination of Phalaenopsis.

Meloidogyne enterolobii is a pathogen causing significant damages to pepper production. Utilization of resistant cultivars is the most economical and environmentally friendly method to control this disease. A deeper understanding of the regulatory mechanisms of resistance to root-knot nematodes could facilitate the breeding process of disease-resistant cultivars. In previous studies, analysis of transcriptomic data of Hainan local M. enterolobii-resistant pepper germplasm CF25 before and after inoculation were carried out to explore metabolic pathways closely related to nematode resistance. In order to further explore the regulatory mechanisms of resistance, sRNA libraries of CF25 before and after inoculation with M. enterolobii were sequenced to identify a total of 133 differentially expressed miRNAs. Based on the criteria of P≤0.05 and |log₂(FC)|≥3, 33 significantly differentially expressed miRNAs were identified, including 19 known miRNAs and 14 newly discovered miRNAs. Target gene prediction for the 33 miRNAs yielded a total of 373 target genes, with miR5658-z having the highest number of predicted target genes. GO and KEGG analyses showed that the target genes were mainly enriched in pathways related to plant-pathogen interactions and signal transduction. It is speculated that miRNA-mediated signal transduction and plant defense responses might be important reasons for the resistance of CF25 to M. enterolobii. To preliminarily verify the regulatory relationships between differentially expressed miRNA and the target genes, six differentially expressed miRNA and the target genes were selected for qRT-PCR validation. The results showed that the differential expression trends of miRNA and target genes were consistent with the high-throughput sequencing results and generally conformed to the negative regulation pattern between miRNA and the target genes. The results of this study suggest that miRNA may play significant roles in the defense response to root-knot nematodes and lay the foundation for furtherly elucidating the mechanisms of miRNA-mediated nematode resistance in pepper.