The problem of heavy metal pollution of crops occurs frequently, and heavy metal pollution has become one of the important factors affecting crop quality. By applying 0.75, 1.50 and 3.00 g/kg potassium sulfate into soil under cadmium (Cd) stress, the effects of potassium fertilizer on the physical and chemical properties of rhizosphere soil and cadmium accumulation in plants of Ilex asprella were studied. This study is expected to lay a foundation for the development of cadmium excess reduction technology in Ilex asprella. The result shows that, the application of high amount of potassium sulfate fertilizer could reduce the soil pH by 1.72% to 8.09%. Cadmium stress can reduce the content of soil organic matter, and the application of medium (1.50 g/kg) and high (3.00 g/kg) amount of potassium sulfate can increase the content of soil organic matter, total potassium and available potassium. In addition, the application of potassium sulfate generally increased the content of biologically available cadmium in the soil, only on the 30th day after the application of low concentration of potassium sulfate (0.75 g/kg), the content of bioavailable cadmium in the soil decreased by 1.94% compared with the Cd treatment group. Under cadmium stress, the application of potassium sulfate could increase the SOD activity in leaves of Ilex asprella, and then enhance the tolerance to cadmium stress. Low could increase the SOD activity in leaves of Ilex asprella, and then enhance the tolerance to cadmium stress. Low concentration of potassium sulfate (0.75 g/kg) inhibited the transport of cadmium from rhizome to leaf and effectively reduce the accumulation of cadmium in the root and stem of Ilex asprella. To sum up, the application of high amount of potassium fertilizer decreased the soil pH, and the application of medium (1.50 g/kg) and high (3.00 g/kg) amount of potassium sulfate could increase the content of soil organic matter, total potassium and available potassium, thus improved soil fertility. The results also showed that low concentration of potassium sulfate could reduce the content of bioavailable cadmium in soil, inhibit the transport of cadmium from roots and stems to leaves, and reduce the accumulation of cadmium in roots and stems of Ilex asprella.

Two genuses and species of Orchidaceae, Taeniophyllum glandulosum Blume and Tainia dunnii Rolfe, together with other two species, Bulbophyllum henanense J. L. Lu and Goodyera yangmeishanensis T. P. Lin, were reported as new records to Hubei province. The morphological characteristics were briefly described, and color photos were provided. The new records enrich the wild orchid resources and are of great significance for further study of orchid plants and biodiversity conservation in Hubei province.

In order to reveal the genome characteristics of HNU24, which has excellent antagonistic ability to Ralstonia solanacearum, its complete genome was sequenced by the BGISEQ-500 and ONT PromethION technology, and the genome assembly, gene prediction, function annotation, and protein homology analysis also were conducted. Phylogenetic analysis results demonstrated that HNU24 belonged to Bacillus velezensis. Its completed genomic sequence length was 3 932 768 bp, GC content was 46.48%, and had 3822 genes. A total of 43 carbohydrate active enzyme gene families were identified in the genome, and the cellulase activity experiment further confirmed that the strain HNU24 had the ability to degrade cellulose. Thirteen clusters of secondary metabolite biosynthesis genes were predicted in genome, including eight compounds: surfactin, fengycin, plantazolicin, butirosin A/butirosin B, macrolactin, bacillaene, difficidin, bacillibactin and bacilysin, which have been reported as the antibacterial components. Five unknown components, which were found no homologous genes or were less similar to the known database sequences, may be new compounds that have not been identified and reported. In addition, greenhouse experiment demonstrated that HNU24 had significant growth promoting effect on tomato plants. Thus, HNU24 may antagonize R. solanacearum and promote tomato growth by secreting active compounds, and it is a potential biofertilizer strain. The relevant results would lay a foundation for further research and application of HNU24 in biological control.

In this study, seven LysM-RLK subfamily genes were systematically identified in the whole genome of papaya using bioinformatics methods, and the chromosome distribution, gene structure, protein physical and chemical properties, and subcellular localization information were analyzed. Familial evolutionary analysis showed that papaya LysM-RLK could be further divided into three subgroups (Lym-Ⅱ, Lym-Ⅲ, Lym-Ⅳ), distributed on four chromosomes. Recent gene replication is the main driver of the evolution of the papaya LysM-RLK subfamily. The analysis of promoter sequence regulatory elements found that it contained multiple photoresponse elements and elements involved in low temperature response and stress related hormone signal response. Large-scale comparative transcriptome analysis systematically analyzed the gene expression patterns of LysM-RLK under papaya biostress and abiotic stress and different tissues, revealing its specific expression patterns and potential biological functions. The expression differentiation of replicating gene pairs, differences in domain composition, and changes in the tertiary structure of proteins suggest subfunctionalization in the process of evolution. Core co-expression network analysis under biotic and abiotic stress conditions identified 27 core genes strongly associated with LysM-RLK3, revealing the potential transcriptional regulatory patterns of LysM-RLK3. The results would provide important insights into the evolution, functional differentiation and role of the papaya LysM-RLK subfamily in adversity response and growth and development.

To effectively monitor the occurrence and damage of dangerous pests in Zhaoshu Island, a systematic survey and risk assessment on all the pests of 90 plants in Zhaoshu Island was conducted. The results showed that there were 19 insects and mintes of 8 wild halophytes including 5 alien invasive pests and 7 world dangerous pests occurred and harmed seriously; 24 insects and mintes of 29 landscape plants including 9 alien invasive pests and 6 world dangerous pests occurred and harmed seriously; 36 insects and mintes of 31 salt-tolerant fruits and vegetables including 7 alien invasive pests and 6 world dangerous pests occurred and harmed seriously; 16 insects and mintes of 22 sand-bander plants including 5 alien invasive pests and 2 world dangerous pests occurred and harmed seriously. The results of risk assessment showed that Brontispa longissima, Paracoccus marginatus, Phenacoccus solenopsis and Opisina arenosella were all high-risk pests in Zhaoshu Island with R value 2.12, 2.12, 2.09 and 2.02, while Dysmicoccu neobrevipes, Diaspis boisduvalii, Tetranychus urticae, Thrips palmi, Bemisia tabaci, Liriomyza sativae and Bactrocera cucuribita were all moderate risk pests in Zhaoshu Island with R value 1.92, 1.89, 1.82, 1.79, 1.79, 1.74 and 1.61, respectively. The results were the first report on the occurrence and damage of plant pests in Zhaoshu Islan, which would provide an important basic information support for the effective protection of the biosafety in Zhaoshu Island.

In this paper, a combination of traditional morphological features and modern molecular phylogenetic analysis was used to identify and describe a gasteroid fungus collected from Guangdong. The studied specimens is Asperosporus subterraneus Karlsen-Ayala, Gazis & M.E. Sm., a member of the new genus Asperosporus Karlsen-Ayala, Gazis & M.E. Sm. of Agaricaceae which newly reported from Florida, USA, and firstly reported from China. A. subterraneus was mainly characterized by its irregular spherical basidiomata, white to grayish white at first, then becoming brownish when mature, rapidly stain pinkish-red when cut or bruised, earthy smell, Basidiospores, 14-18 μm×11-16 μm, broadly elliptical to subglobose and thick-walled basidiospores ornamented with larger pyramidal to irregular warts, turn to orange brown in 5% KOH solution and dark brown when added to Melzer solution, and the spores were often attached with sterigma remnants. Specimens were deposited in the Fungarium of Guangdong Institute of Microbiology (GDGM).

In order to explore the effects of different rainfall and stand types in the same area on vegetation diversity, three regions with large annual rainfall differences in Hainan were selected to conduct vegetation diversity control experiments with different stand types. The results showed that 61 species, 58 genera, 45 families were present in the natural forests, 39 species, 37 genera, 26 families were present in the Eucalyptus plantations, and the vegetation diversity of Mangifera indica plantations, Acacia mangium plantations and Hevea brasiliensis plantations was relatively low due to frequent artificial management. The effects of rainfall on species diversity index of natural forest were significant (P<0.05), but no significant difference was found in Eucalyptus plantation (P>0.05). The species richness index (R) of natural forest and Eucalyptus plantation increased gradually with the increase of rainfall. The Shannon-Wiener diversity index (H), Simpson diversity index (D) and Pielou evenness index (J_sw) of tree layer and shrub layer of natural forest decreased with the increase of rainfall, while the herbaceous layer did the opposite. Shannon-Wiener diversity index, Simpson diversity index and Pielou evenness index of shrub layer and herb layer of Eucalyptus plantation increased with the increase of rainfall. The fluctuation of species diversity index was mainly in shrub layer and herb layer of natural forest and Eucalyptus plantation, and the change of tree layer was relatively stable. The rainfall and canopy shaded effect were the important reason for the differences in regional species diversity, compared with natural forest of Eucalyptus plantation tree layer the lack of ecological niche of the vegetation diversity was the main reason for the low and had nothing to do with the tree itself, specific provisions of other economic forest caused by frequent grass fertilizer management was relatively single species diversity. Therefore, the key to improve species diversity of the plantation is to establish a mixed or different-age forest to transform the existing pure forest to promote the release of the niche of the tree layer and change the management mode of other economic stands at the same time.

Species diversity is the most basic level of biodiversity, which not only reflects the richness of biological species, but also the spatial scope of species evolution and the ecological adaptability to specific environments. Structure is the basis for studying the historical dynamics of plants, and while understanding and clarifying the growth competition relationship between species, it reflects the trend of community succession. Based on the results of 62 plots with a total area of 3.72 hm², the species diversity and structure of tree populations of Dagangshan were analyzed. There were 486 species of plants in the community, belonging to 286 genera of 120 families, of which single species accounted for 66.43% of the total, and China fir were in a dominant position in the community. Dagangshan is located in the subtropical region and has the nature of transition zone. The genus of seed plants included 13 distribution types, and 9 genera with endemic components in China. Shannon-Weiner index, Simpson index and Pielou index were basically the same in the distribution trend of each growth layer. The advantage of shrub layer was obvious. The herbaceous layer was slightly higher than the arbor layer. The overall species diversity index of the community was higher and the species were more abundant. By sample belt, the 2nd sample was the most abundant, and the 1st sample was slightly lower than the others. However, the community similarity was the highest in the 1st and 2nd belts, and the difference in species diversity indices in the 3rd and 4th samples was small, but the community differences were the largest.

In three Camellia vietnamensis producing areas of southwest tropical rainforest in Hainan Province, Baomeiling Ecological Protection Reserve (JB), Bawangling Gibbon Reserve (QS), and Jiangpai Village (XS), Baisha Li Autonomous County, 22 high-yielding single strains were selected, for primary screening and comparison. Observe fruit yield per unit area, oil content rate of fresh fruit, grude oil yield per unit of crown area, peroxide value, iodine value, acid value, saponification value and the contents of palmitic acid, stearic acid, oleic acid, linoleic acid, myristic acid, palmitoleic acid, linolenic acid, arachidic acid, eiconsenoic acid in seed oil for 3 years, after the data was treated with the methods of ANOVA, gray association analysis, and cluster analysis, then screen out the more superior single strains. There existed significant difference in grude oil yield per unit of crown area, oil content rate of fresh fruit and fruit yield per unit area, among them, fruit yield per unit area might be the key indicator of high-yield screening. The physicochemical nature and fatty acid content of camellia seed oil both meet the requirements of "oil-tea camellia seed oil" (GB/T 11765—2018), but there existed some significant difference in some indicators, and there existed the linear correlations between some saturated and unsaturated fatty acids, then there existed the phenomena of the saturated acids changed into unsaturated acids, indicating that the camellia seed oil has no quality problems, and the different tree had its specific characteristic, so the breeding target should be mainly high yield and stable yield, and iodine value, saponification value and the contents of oleic acid might be the effective indicators for selection. Known from the grey association analysis data, the single strains with superior integrated traits were successively JB2, JB7, QS6, JB1, QS5, XS2, JB4, XS4, JB9 and XS5 respectively; Known from the clustering results, it is better to gather all the individual strains into 9 categories (r=0.904), among them, the top seven single strains of comprehensive traits were clustered in Ⅰ, Ⅸ,Ⅶ and Ⅵ respectively, indicating it was expected to screen out the characteristic diverse varieties. JB2, JB7, QS5, XS2 and XS4 belonged to the expected individual strains whose comprehensive behaviors in economic traits were excellent, and JB2 among them was the best one and rare.

In order to explore the pollution level and source of soil heavy metals in Haikou City, taking the agricultural land in Haikou City as the research object, the content of eight kinds of heavy metals such as Cd, Hg, As, Pb, Cr, Cu, Ni and Zn in soil surface samples were collected and determined, and the spatial distribution characteristics of heavy metals were clarified combined with geostatistical analysis method. The single factor pollution index method, geo-accumulation index method and potential ecological risk index method were used to evaluate soil pollution. The source of heavy metals was quantitatively analyzed by the correlation analysis and principal component analysis/absolute principal component fraction (PCA/APCS) receptor model. Six heavy metals such as Cd, Pb, Cr, Cu, Ni and Zn exceeded the risk screening value of agricultural land, and the proportion of exceeding the standard points from high to low was Cr, Ni (31.6%)>Cu (21.1%)>Cd (5.3%)>Pb and Zn (2.6%). The spatial distribution characteristics of Cu, Zn, Ni and Cr contents were basically the same, which were similar to the distribution of basic volcanic rocks in the study area. The evaluation results of heavy metal geo-accumulation index showed that the concentration of Cd in the soil was the highest, and the soil was greatly affected by Cd, followed by Cr, and other heavy metals were less affected. The potential ecological risk levels of soil heavy metal pollution were mainly mild and moderate risk levels, while As, Pb, Cr and Zn were slight ecological risks, and the potential ecological harm was small. The above points of Cd, Hg and Ni intensity ecological risk accounted for 52.6%, 15.8% and 5.3% respectively. The potential ecological risk of soil heavy metals in the study area was mainly caused by Cd and Hg. Eight kinds of heavy metal elements were identified as three sources. Cu, Ni, Cr and Zn were mainly from natural sources, which were mainly affected by the high soil background value of basic volcanic parent rock, Pb, Cd, As and Hg were mainly from industrial sources and traffic sources. As was also affected by agricultural sources. The source of heavy metals in Haikou soil was relatively single. As a result, it is necessary to strengthen the pollution control of Cd, Cr and Hg in the soil, with the focus on the pollution control of Cd.