Japonica rice in Jiangxi, China has been planted for 11 years recently. In order to further elucidate the blast resistance of Jiangxi late japonica conventional rice, and select main parents for indica infiltrating japonica rice, 28 main japonica and 54 main indica parents were evaluated in Jinggangshan, Jiangxi with blast resistance gene markers Pi37/Pi35/Pish, Pi5, Pi2, Pi9, Pia, Pi23, Pigm, Pi33/Pi42, Pi56, piks/kg(t)/ks/KP/km/kh/43 and Pikh. Among the 28 japonica rice parents, one contained seven of the eleven resistance genes, five contained six resistance genes, seven contained five resistance genes, twelve carried four resistance genes, and three carried three resistance genes. The distribution frequency of Pia was as high as 78.6%, followed by Pikh and Pi9 with frequency 0.643, but the resistance frequency of Pigm and Pi37/Pish in japonica varieties was 0. In 54 indica rice parents, eight carried seven resistance genes, ten carried six resistance genes, 13 carried five resistance genes, 17 carried four resistance genes, four contained three resistance genes, and two contained two resistance genes. The highest resistance frequency 0.981, was observed in Pi9, followed by Pik/Pikh/Piks, 0.833. The frequency of Pigm, Pi37/Pish, Pikh, Pia, Pi5, Pi2, Pi23 and Pi33/Pi42 was 0.556, 0.537, 0.519, 0.389, 0.352, 0.315, 0.167 and 0.111, respectively. The resistance frequency of Pi56 in indica rice was 0. Identifying the distribution of resistance genes in these materials would indicate the direction for creating indica-japonica materials and selecting main parents for reconstituting broad-spectrum and persistent resistance genes.

A MYB transcription factor gene, belonging to R2R3, was cloned by the results of the transcriptome sequencing of pineapple (Ananas comosus), which was named AcoMYB1 and the GenBank accession number was XM_020230319. The full length cDNA and coding region (ORF) was 1221 bp and 747 bp, encoding 248 amino acids with two conserved SANT domains at N-terminal. By bioinformatics analysis, AcoMYB1 was an unstable hydrophilic protein without transmembrane structure and signal peptide, which may be located in the cytoplasm, and the secondary structure mainly had alpha helixes and random coils. Real-time fluorescence quantitative PCR analysis showed that AcoMYB1 was induced by drought and low temperature stress, and showed a trend of “up first then down”, and the expression was also induced in the fruit development of early and late maturing varieties, which showed a tendency of “up-down-up”, especially in the early stage of fruit development and the later stage of fruit maturation. Therefore, it is speculated that AcoMYB1 as a positive regulatory factor is involved in the response process of chilling injury and drought stress, and plays a regulatory role in the early fruit development and late fruit maturation of pineapple (Ananas comosus).

Bio-control strain Bacillus velezensis Z shows good effects on the control of various diseases, especially good for the black pepper Phytophtora foot rot disease. The whole genome sequencing is an important basis to further study the molecular mechanism. In this study, the whole genome of the strain was completely sequenced using both Illumina HiSeq 4000 and PacBio RS II, and the gene function annotation, analyses of comparative genomics and secondary metabolite biosynthetic gene clusters were performed using blast alignment tools. The complete genome sequence of B. velezensis Z was consisted of a circular 4 054 780 bp chromosome and a 17 122 bp plasmid with GC content of 46.24%, 4173 identified genes, 27 rRNA, 86 tRNA, 34 sRNA, 179 tandem repeat regions including 138 minisatellite DNA and 13 microsatellite DNA. The genome showed highly homologous with the model strain B. velezensis Z FZB42 by the analyses of core/pan gene and gene family. B. velezensis Z harbored 13 secondary metabolite biosynthetic gene clusters, including 8 clusters involved in the synthesis of surfactin, plantazolicin, macrolactin H, bacilysin, fengycin, difficidin, amylocyclicin, bacillaene, and others functionally unknown. In conclusion, the genetic information, comparative genomics and antibiotics synthesis gene clusters of the B. velezensis Z were revealed in this study, and it would be useful for further research and utilization of the strain.

Citrus maxima ‘Liuyuezao’ is a precocious bud mutation of Guanximiyou, an important pomelo variety of China. In this study, the whole genome resequencing of C. maxima ‘Liuyuezao’ was conducted using next-generation sequencing. The chloroplast (cp) genome was assembled and annotated. The cp genome had a total length of 160 186 bp, the tetrad structed was consisted with large single copy (LSC), small single copy (SSC) and inverted repeat (IR), with the length in 87 939 bp, 18 395 bp and 26 926 bp respectively. The cp genome contained a total of 133 genes, including 89 protein-coding genes, 37 tRNA genes and 8 tRNA genes. We identified 31 tandem repeat and 101 SSRs. Combined with 29 published cp genome sequences of Rutaceae, we used the maximum likelihood method to reconstruct the phylogenetic relationship of Rutaceae. The result showed that C. maxima ‘Liuyuezao’ had a close relationship with C. sinensis, C. limon and C. platymamma.

Using Zea mays ‘B73’ as the internal reference, the genome size of 66 Jasminum sambac germplasm (16 collected germplasms and 50 seedings) were estimated by the flow cytometry, and the ploidy was calculated using diploid as the control. Using Zea mays ‘B73’ as the internal parameter could effectively estimate the genome size of J. sambac, the peaks of the samples under test could be separated completely, and no overlapping peaks and peaks could be clearly concentrated. 56 germplasms were diploid with genome size between 0.54 Gb and 0.63 Gb, Seven germplasms were triploid with genome size between 0.79 Gb and 0.96 Gb, Three germplasms were tetraploid with genome size range from 1.04 Gb to 1.12 Gb. Three tetraploid and two triploid were found in the seedings, which showing that seed selection is an effective way of germplasm innovation for J. sambac. All the tetraploid and triploid blossomed were simple flower. The results of the study wouldl provide important reference basis for the ploidy breeding and seed selection of J. sambac.

The DNA-binding one finger (DOF) transcription factor family is a major family of plant-specific transcription factors containing the DOF domain. These transcription factors are involved in a variety of functions of importance for different biological processes in plants. In the current study, an overview of 8 DOFs genes in maize is presented, including the gene structure, chromosome location, phylogeny, proten motif and expression pattern in responses to various abiotic stresses. Expression patterns indicated that the eight ZmDOFs had tissue specific expression patterns, indicating these genes are crucial in maize growth and development. Moreover, we examined the transcriptional levels of the eight ZmDOFs under salt and PEG6000 stress treatments, seven ZmDOFs and six ZmDOFs were up-regulated after salt and PEG6000 treatment, respectively. We also analyzed the eight ZmDOFs profilling under ammonium and nitrate stress treatment, seven and eight ZmDOFs significantly responded to these two stresses, indicating they are associated with nitrogen stresses responses. The results would provide a very useful reference for the cloning and functional analysis of the members of this gene family in maize and other species.

Allene oxide cyclase (AOC) is a key enzyme in the synthesis pathway of jasmonic acid and plays an important role in plant defense reactions. In this study, an AOC gene was cloned based on the sugarcane transcriptome database and named ScAOC. Biological analysis, tissue-specific analysis, and expression analysis under stress were conducted to understand the preliminary function of the gene. The open reading frame (ORF) of the ScAOC gene in sugarcane was 744 bp, encoding 244 amino acids, and its protein molecular mass was 26.37 kDa. Bioinformatics analysis showed that the ScAOC protein was an unstable basic hydrophilic protein and contained a conserved domain of the PLN02343 domain of Allene_ox_cyc Superfamily. Constructing a phylogenetic tree showed that the ScAOC protein has a high homology with sorghum protein. Fluorescence quantitative PCR showed that the ScAOC gene was expressed in the roots, stems and leaves of sugarcane, and the expression levels from high to low were leaves, roots and stems. Under the stress of PEG, NaCl and exogenous MeJA, the relative expression of ScAOC gene increased first and then decreased, and ABA had a certain inhibitory effect on the expression of ScAOC. Under the stress of pathogenic bacteria and armyworm feeding, the relative expression of ScAOC gene increased significantly. The results showed that ScAOC maight be involved in the defense response of sugarcane to biological or abiotic stress.

Thioredoxin plays an important role in seed germination, redox homeostasis, signal transduction and responses to biotic and abiotic stresses. In this study, AhTRX h, a member of h-thioredoxin subfamily, was cloned from peanut varieties ZH2 (Al-sensitive) and 99-1507 (Al-tolerant). Sequence analysis showed that AhTRX h contained an open reading frame (ORF) of 429 bp encoding 142 amino acids with a conservative active site-WCGPC. Phylogenetic analysis showed that AhTRX h was closely related to TRX h in Cicer arietinum and Th9 in Arabidopsis. AhTRX h was located in chloroplast. The recombinant plasmid pGEX-6p-1-AhTRX h was transformed into Escherichia coli (Rosetta), recombinant proteins induced by IPTG were founded in supernatant and precipitate. Soluble recombinant proteins with activity were purified, and had no obvious trend of S-nitrosylation in vitro. The results of yeast two hybrid showed that potentially interactional proteins were calreticulin and metallothionein. The results indicate that AhTRX h play an important role in response to Al toxicity by likely interacting with calreticulin and metallothionein.

In this study, the high-throughput sequencing of the transcriptome of sisal was used to seek SSR loci and develop SSR markers by MISA 1.0 and Primer 3.0 softwares, respectively, and preliminary primer verification and polymorphic primer analysis were performed by vertical acrylamide gels. A total of 13 175 of SSR loci were found in the 70 110 unigene sequences. The SSR distribution frequency was 15.61%. In total, 60 repeat elements were obtained, among them, mono- nucleotides were the domiant repeat motif (37.96%), followed by di-nucleotides (32.92%), and tri-nucleotides repeats (27.90%), the other repeat types occupied 1.21% in all. The most dominant mono-nucleotide, di-nucleotide and tri-nucleotide repeat motif was A/T, AG/CT and AAG/TTC, respectively. Among the 100 pairs of SSR primers randomly selected from the designed SSR primers of Rema No. 1, sixty-eight pairs of primers could amplify the expected size bands, and eighteen primers showed polymorphism among six sisal germplasms. The obtained primers would provide effective molecule markers for genetic diversity analysis and germplasm identification of sisal.

Phospholipase C (PLC) is widely involved in the life activities and metabolism processes of plants, and plays an important role in the process of resisting fungal infection. Based on the results of the transcriptome sequencing in Gerbera jamesonii, 13 members of G. jamesonii PLC gene family, including 3 NPC and 10 PI-PLC were identified in the study. The sequences of G. jamesonii PLC proteins ranged from 98 to 594 aa in length, theoretical molecular weight varied from 11 410.25 to 67 998.85 kDa, isoelectric point in the range of 4.74 to 9.59, and all were unstable hydrophilic proteins. The prediction results of subcellular localization showed that the 13 members were located in the cell wall, cell membrane, cytoplasm, chloroplast and nucleus, indicating that there might be diversity in functions of different members. Evolutionary trees analysis showed that 13 PLC proteins of G. jamesonii were divided into two subgroups, the structure and composition of proteins with relatively close evolutionary relationship were similar. G. jamesonii’s homologous protein PLC2, PLC4 and AT2G40116 in Arabidopsis thaliana can interact with each other. The FPKM value analysis of G. jamesonii transcription showed that GjPLC2, GjPLC3, GjPLC8 and GjPLC10 were highly expressed in G. jamesonii and changed greatly in infected plants, which may play an important role in preventing fungal infection. These results could provide the basis for further study of the biological function of G. jamesonii PLC genes.

Salt stress is one of the important environmental factors affecting crop growth and development. Identifying new salt tolerance genes and revealing their possible mechanisms and applying them to the creation of new germplasm and the selection of new varieties is one of the important ways to improve the salt tolerance of rice. In this study, 58M and 58L strains with different salt tolerance independently selected by the laboratory were used as experimental materials. The young panicles of rice were collected after treatment with 0.6% NaCl for 0, 6 and 24 h, and the transcriptome sequencing study was conducted. The results showed that with 0 h young ears as the control, the 58M strain detected 1483 genes up-regulated and 1085 genes down-regulated after 6 h salt stress; 937 genes were up-regulated and 459 were down-regulated after 24 h salt stress. In the 58L strain, 931 genes were up-regulated and 2 614 were down-regulated after 6 h salt stress; 930 were up-regulated and 1 299 were down-regulated after 24h salt stress. Through the Venn diagram analysis, it was found that 178 genes were up-regulated in 58M strains and down-regulated in 58L after 6h salt stress; 30 genes were up-regulated in 58M and down-regulated in 58L after 24 h salt stress. These 208 target genes were subjected to GO function enrichment analysis and KEGG pathway analysis. GO analysis found that these differential genes accounted for 40.43%, 31.56% and 28.01% respectively, in the three main categories of biological process, cellular component and molecular function; KEGG Pathway analysis results showed that the pathways of these differential genes were significantly enriched include diterpene biosynthesis, amino acid sugar and nucleotide sugar metabolism, phenylpropane biosynthesis, biotin metabolism, metabolic pathways, biosynthesis of secondary metabolites, α-linolenic acid metabolism, fatty acid biosynthesis and biosynthesis of unsaturated fatty acids etc. In addition, a total of five important transcription factors were discovered through the mining of target genes. This study would provide a reference for studying the molecular mechanism of salt tolerance in young panicles through transcriptome analysis of rice young panicles.

In order to obtain reliable gene expression results for TPD-related study of rubber tree, the selection of suitable reference genes is very important. In the present study, using the latex from the healthy rubber tree, the third grade tapping panel dryness (TPD) tree and the TPD-recovering tree of ‘Reyan7-33-97’ as the experimental materials, the expression stability of 20 candidate reference genes were evaluated by using quantitative real-time PCR (qTR-PCR) and softwares of geNorm, NormFinder and BestKeeper. The results showed that, reference genes eif2、ACT7a and UBC2b were the top three stable genes in the healthy tree; UBC3、eifAb、eifAa、ADF4、UBC4、UBC2b、eif2、RH2b and ACT7b were all stable genes in the third grade TPD tree; UBC2b、eif2 and ROC3 were stable genes for the TPD-recovering rubber tree. Based on the different stable reference genes, relative expressions of HbDXS1, HbHMGS2 and HbNIN3 genes were analyzed respectively. The results showed that eif2 and UBC2b were a couple of stable reference genes for TPD-related study; the eif2 was the most stable internal reference gene; 18S gene was not suitable as reference gene for qTR-PCR in this study.

In order to better understand the function of LcMYB1 and provide theoretical support for further utilization, LcMYB1 was transformed into both petunia and tomato. White flower ‘W115’ petunia and ‘Micro-Tom’ tomato were used as materials in LcMYB1 ectopic expressed assays. Anthocyanin contents and related gene expressions were analyzed in transgenic plants. Ectopic expression of LcMYB1 in ‘W115’ resulted in anthocyanin production in vegetative and floral tissues such as leaves and petals, probably by transcriptional activation of anthocyanin biosynthetic genes such as PhCHS and PhDFR and endogenous anthocyanin regulatory gene PhAN1. However, the transgenic tomato only produced anthocyanin in anthers and leaves but not in tomato fruits and petals. The results suggested that LcMYB1 could enhance anthocyanin production in vegetative and floral tissues of both petunia and tomato by activating anthocyanin biosynthesis and regulatory genes. LcMYB1 is an important transcriptional regulatory factor in anthocyanin biosynthesis of plants and is potentially used in ectopic transformation.

Arecanut (Areca catechu L.) is an important tropical economic and social importance plant in Hainan Province. It has high medicinal value and is listed as the first of the four south China medicinal plants. Areca is mostly planted in underdeveloped areas, and the basic research is weak. The germplasm diversity of areca from Hainan remains unclear due to lack of systemic research of germplasm. We analyzed the genetic diversity among 58 arecanut accessions from Hainan by SSR molecular marker technology to clarify the genetic relationship and provide a theoretical basis for the hybrid breeding and functional gene mining. The results showed that 32 primers with high polymorphism and clear bands were screened out from 500 SSR primers. A total of 79 alleles were detected from the 58 arecanut germplasm resources, and there were 2-5 loci per SSR, with an average of 2.4688 alleles at each marker, and the number of effective allele was accounted for 58.92% of the observed one. The range of PIC was 0.0169-0.5969, with an average of 0.2254. The Shannon index (I) of all primers ranged from 0.0496 to 1.2552, with an average of 0.4496. Nei’s genetic diversity index (Nei) was ranged from 0.0171 to 0.6492, with an average of 0.2596. The genetic diversity of alleles detected by SSR primers was low. UPGMA Cluster analysis showed that the genetic diversity of group V was the richest. Genetic analysis showed that the 58 arecanut were separated from the effect of regional isolation. The conclusion of frequent exchanges among different regions of arecanut in Hainan and lower genetic diversity in Hainan cultivars would provide theoretical guidance for the selection of parents in the genetic breeding of arecanut, while reference for collecting germplasm to supplement different resources in the future.

Early and rapid identification of F₁ hybrid progeny of Hevea brasiliensis and acquisition of true hybrids are of great significance to the creation and genetic research of H. brasiliensis. In this paper, ‘PR107’ and ‘93-114’ were used to hybridize, and three pairs of polymorphic complementary primers were selected from 104 pairs of SSR primers. The results showed that all 35 hybrid progenies were identified as true hybrid seedlings. All the three pairs of polymorphic primers screened had high heterosis identification rate, and the reliability of the identification of genuine and false hybrids was verified by one pair of primers, which could be used as ideal SSR molecular markers for the authenticity identification of rubber tree hybrids later.

In order to accurately identify pitaya cultivars and evaluate their genetic diversity, 20 pairs of SSR core primers were used to analyze the genetic diversity of 58 pitaya varieties, and polymorphic alleles were detected by capillary electrophoresis. Totally, 116 polymorphic alleles were revealed, with an average of 5.8 for each primer pairs. The average number of alleles (Na), number of effective alleles (Ne), observed heterozygosity (Ho), expected heterozygosity (He), and polymorphism information content (PIC) was 5.8, 2.0519, 0.3318, 0.4603 and 0.417, respectively. Based on the clustering results of genetic similarity coefficient, the main commercial cultivars of pitaya were divided into three groups. Based on 20 pairs of SSR primers amplified from 58 cultivars, the fingerprints of 58 cultivars of pitaya were constructed using 9 pairs of primers. A strategy of combining primer pair with distinct alleles for fingerprint construction was developed and applied to the 58 cultivars. The confidence probability of variety identification was almost 100%. The research results would provide important theoretical basis and technical support for the germplasm classification, cultivar identification and varieties property protection of pitaya.

To obtain the material of polyploid medicinal marigold, colchicine was used for the polyploid induction with the seeds of medicinal marigold ‘Neimeng No. 1’. The results showed that 0.15% of colchicine treated for 24 h was the best selection of the seedling induction of Tagetes erecta, reaching 56% of mutation rate. The seedlings were planted in the field and preliminary screening and marking of morphological variant plants were carried out. Seeds were harvested after pollination and seeded and morphological indicators of progenies were observed. Flow cytometry was used to detect the plants with obvious morphological variation and a total of fifteen tetraploid plants were identified. By contrast, the stem diameter, palisade tissue thickness, ratio of palisade tissue to spongy tissue and single flower weight of tetraploid plants were significantly higher than those of diploid plants, and the total leaf weight, leaf width, leaf length-width ratio, leaf stomatal density and number of flowers per plant of tetraploid plants were significantly lower than those of diploid plants. The total flower weight per plant of tetraploid plants was significantly increased in contrast to that of diploid plants.

To explore the effect of melatonine (MT) on the physiological mechanism of Calendula officinalis seedlings under salt stress, a pot-sand culture method was used to study different concentrations of exogenous melatonin (0, 50, 100, 200 μmol/L MT) effects on the growth, photosynthesis and physiological characteristics of C. officinalis seedlings under different levels of salt stress (0, 100, 200 mmol/L NaCl). The results showed that 100 and 200 mmol/L NaCl stress severely restricted the growth of C. officinalis seedlings, reduced chlorophyll content, photochemical fluorescence efficiency and photosynthesis intensity. The content of MDA and H₂O₂ increased, which intensified the degree of lipid peroxidation, induced POD enzyme activity and proline content increased. Treatment with exogenous melatonin could effectively alleviate the damage of salt stress to marigold seedlings. The plant height, stem circumference, shoot and root dry weight under 100 μmol/L MT treatment increased by 17.35%, 17.64%, 32.14% and 19.83%, respectively compared with the control. Chlorophyll content and F_v/F_m increased by 71.96% and 4.13%, respectively. The photosynthesis parameters P_n, G_s and T_r increased by 88.74%, 97.21% and 58.88%, respectively, while C_i decreased by 18.07%. The content of MDA and H₂O₂ reduced by 33.77% and 64.29%, POD, CAT enzyme activity, soluble protein, and proline content increased by 118.02%, 67.29%, 55.47% and 56.30%. Under salt stress conditions, MT treatment could effectively increase the activity of antioxidant enzymes and reduce the level of lipid peroxidation, promote the accumulation of soluble protein and proline, improve photosynthetic fluorescence characteristics, and ultimately promote the growth of C. officinalis seedlings.

In order to investigate the effects of doubled atmospheric CO₂ concentration on the photosynthetic characteristics and growth of Dendrobium huoshanense, the photosynthetic characteristics, vegetative growth and contents of effective constituents of D. huoshanense were evaluated using the seedlings after doubled atmospheric CO₂ concentration treatment (800 μmol/mol, 400 μmol/mol as control) for 180 days. The results showed that the net photosynthetic rate, stomatal conductance, transpiration rate and instantaneous water use efficiency significantly increased in leaves compared with the control. There was not photosynthetic acclimation during the experiment. After cultivation for 30 days, the survival rate, rooting rate and number of new buds of the treatment group were always significantly higher than that of the control group, while the soluble protein content in leaves of the treatment group was significantly lower than that of the control group after 60 days. Stem fresh weight, stem dry weight, stem height, leaf number per plant and leaf thickness also significantly increased in the treatment group, but there was no significant effect on stem thickness and leaf area. Moreover, the polysaccharide content of stems significantly increased in the treatment group, with 94% higher than that in the control group, while the alkaloid content significantly decreased, and there was no significant difference in the contents of total amino acid content and total flavonoids between the two groups. In conclusion, doubled carbon dioxide concentration treatment could significantly promote the growth, increase the survival rate, stem yield and stem polysaccharide content.

In order to determine the effect of different planting density on the characteristics and yield of mechanically harvested pepper, four planting densities (P0: 38 480·hm^-2, P1: 51 307·hm^-2, P2: 76 961·hm^-2, P3: 102 615·hm^-2) were set up for the study of “Layan 102”, which was suitable for mechanized harvesting pepper. Field plot experiments were carried out in Guiyang and Zunyi respectively. The results showed that with the increase of planting density, the plant height increased, and the stem diameter decreased. Under the condition of high density planting (P3), the biomass of root and shoot of pepper reached the minimum. The incidence rate and disease index of pepper increased significantly with the increase of planting density. The highest incidence rate (P3) was found under high dense planting (41.67%) (Guiyang) and 43.33% (Zunyi), and the disease index was 31.05% (Guiyang) and 29.86% (Zunyi) respectively. High planting density led to sharp decline of photosynthesis per plant of pepper: under P1, P2, P3 treatment, the photosynthetic rate significantly decreased by 13.94%, 24.73%, 29.66% (Zunyi) compared with P0 treatment; under the same conditions, the transpiration rate of pepper leaves decreased by 10.02%, 19.81%, 42.12% (Guiyang). The total yield of pepper increased significantly with the increase of planting density, while the yield of commercial fruit increased first and then decreased with the increase of planting density. Compared with P0, P2, P3, the yield of Guiyang pepper commercial fruit increased by 16.43%, 32.81%, and 41.67%, Zunyi by 20.25%, 26.67%, and 61.02% at P1 condition. According to the growth and yield of pepper, the best planting density of ‘Layan 102’ was 51307 pot·hm^-2.

The effect of foliar application with seaweed extract (SE) on the physiological parameters of sugarcane leaves and plant morphological indexes under drought stress were studied to improve the drought resistance of sugarcane. Two sugarcane varieties ‘YT159’ and ‘ROC22’ were used as the test materials. Pot culture was used to foliar application of seaweed extract in different dosages “SE1” and “SE2” under conventional irrigation conditions “C” and drought stress conditions “D”, respectively. Plant morphological indexes including plant height, stem diameter, fresh weight, and leaf physiological parameters including water parameters and antioxidant enzyme activity were measured. The results showed that the physiological parameters in sugarcane leaves and morphological indexes treated with seaweed extract (C+SE1, C+SE2) were not significantly different from those in the C treatment. Under drought stress (D+SE1, D+SE2), the seaweed extract application significantly reduced the leaf dehydration rate, electrical conductivity, proline content, relative water content and fresh plant weight. Besides, drought resistance coefficient was significantly improved, and ‘YT159’ performed better than ‘ROC22’. Therefore, the foliar application with seaweed extract under drought stress could significantly improve the physiological parameters of sugarcane leaves and plant morphological indicators, and increase the fresh plant weight, so as to alleviate the damage of drought stress to sugarcane and improve the drought resistance ability of sugarcane.

The light response curve, CO₂ response curve, and chlorophyll content of Pleione yunnanensis, P. pleionoides, and Pleione barbarae were measured, to study the photosynthetic characteristics and provide a certain theoretical basis for Pleione cultivation. Results showed that all the three species had shade resistance, and the SPAD value of plant leaves was related to its photosynthetic rate. The light compensation point (LCP), light saturation point (LSP), dark respiration rate (R_d), initial quantum efficiency (a), rate of photorespiration (R_p) and CO₂ saturation point (CSP) among the three species were not significantly different. Photosynthesis of P. yunnanensis had a high utilization rate of lower CO₂ and was more suitable for the environment of low CO₂ concentration. P. pleionoides showed a wide range of light adaptation, but it required a higher concentration of CO₂ to increase photosynthetic rate. Pleione barbarae was more sensitive to strong light and easy to occur light suppression phenomenon. Furthermore, the supply of CO₂ may be one of the main factors affecting the increase in photosynthetic rate of plant leaves. To increase yield, shading is needed in cultivation, and appropriately increase the CO₂ concentration will be beneficial to the photosynthesis of these three species.

Biological regulators as a new preparations can promote the natural biological metabolism of crops, enhance the nutrients absorption and utilization, increase the abiotic stress resistance of crops and improve the quality and yield, which is commercially used extensively because of its less dosage and obvious effects. Nevertheless, a large number of biological modulators are flooded with different types, brands and dosage forms in market, interfered seriously with users’ choices and its real effect was difficult to assess. To explore the influence of different biological regulator on fruit quality. Taking the “crystal pomelo” of 5 years old as the research object, a field trial was carried in pomelo science and technology demonstration park, nongdao town, ruili city, in Yunnan province with 97°42° east longitude and 23°52°north latitude. The research area was 0.15 hm², the plant spacing was 3 m×5 m, and the planting density is 660 plant/hm². During the whole growth stage, two times of foliar spraying were applied to each treatment include the beginning of the swelling (May 14, 2019) and bentonite fruiting (June 28, 2019). Four kinds of plant growth regulators (0.1% Clopidourea 100 times: T1; 20% Gibberellic acid 2000 times: T2; 0.015% Brassinolide 2000 times: T3; 99% α-Sodium naphthalene acetate: T4) and three kinds of bio-stimulants (Seaweed essence 800 times: T5; Algal polysaccharides 800 times: T6. Alginic acid 800 times: T7) with water as the control (CK) were foliar sprayed in pomelo growth stage. When the pomelo was maturity (Sep 20, 2019), 5 pomelos were picked from the different growing parts of the tree canopy, middle, lower, inner and outer. Pomelos were picked in each plot, mixed, and then divided according to the method of quartering, 10 fruits were selected as one fruit sample for each repeat. Testing, comparative and analysis 12 kinds of conventional fruit quality indexes (Moisture content, Total soluble solids, Titratable acid, Solid acid ratio, Vitamin C, Sucrose, Glucose Citric, Malate, Pectin, Cellulose and Lignin) and 9 kinds of mineral elements content (N, P, K, Ca, Mg, Fe, Cu, Zn and Ni) under different treatments. The principal factor analysis, cluster analysis and aggregated boosted tree analysis method were used to comprehensive evaluation fruit quality. The results showed that leaf spraying plant growth regulator promoted the soluble solid and titratable acid content significantly. The soluble solids content of pomelo fruits under different treatments ranged from 8.2 to 9.9%. Compared with CK treatment, T1, T2, T3, T4 and T7 treatment significantly increased the soluble solids of grapefruit by 13.1%, 11.9%, 17.9%, 15.5% and 16.7%, respectively. The titratable acid content of pomelo under different treatments ranged from 0.45 to 0.56%. T1, T2, T3, T4, T5 and T6 treatment increased by 17.8%, 13.3%, 24.4%, 11.1%, 15.6% and 22.2% compared with CK treatment. Plant growth regulation and bio-stimulant were significantly increased pomelo fruit glucose content and lignin content, and reduced the content of pectin and cellulose. Compared with CK treatment, T1, T2, T3, T4, T5, T6 and T7 treatments increased glucose content by 29.9%, 155.9%, 140.2%, 99.2%, 43.8%, 46.9% and 61.7%, the contents of pectin in T1, T2, T3, T4, T5, T6 and T7 were significantly reduced by 31.3%, 42.1%, 27.8%, 42.1%, 38.3%, 33.0% and 41.0%, pomelo lignin increased significantly by 215.8%, 182.9%, 156.6%, 332.2%, 196.7%, 119.1% and 263.8%, respectively. As a whole, bio-stimulant facilitated the content of trace elements, but plant growth regulator had no obvious effect on it, both no significantly effect on pomelo NPK nutrient content. Comprehensive analysis found that T3 treatment had an overall best fruit quality, as had the biggest comprehensive score, and cluster analysis also divided T3 treatment into the first group, which showed that its sucrose, malate, and lignin content was the lowest, but soluble solid, solid acid, sucrose, glucose and citric was the highest, the synthesis score was 1.57. Aggregated boosted tree analysis method was used to analysis the relative contribution of fruit quality factors on soluble solids under different groups, further confirmed that the glucose, sucrose and lignin were the top three contributors of different groups under foliar spraying treatment, and primary factors which effect pomelo soluble solids was glucose, sucrose and lignin in turn, the relative contribution rate was 40.2%, 36.0% and 27.2% respectively.

The study was aimed to investigate the effect of reducing fertilizer application and increasing organic fertilizer application on cabbage growth, and to improve the problems of vegetable quality decline, fertilizer utilization rate reduction and soil salinization caused by excessive fertilizer application, etc. Under the condition of winter fallow field planting, taking chicken heart cabbage ‘Tanchun’ as the test material, the effects of chemical fertilizer reduction and organic fertilizer increase on cabbage growth, quality and soil condition were studied by field plots (100% chemical fertilizer, 75% chemical fertilizer+25% organic fertilizer, 50% chemical fertilizer+50% organic fertilizer). The results showed that the reduction of chemical fertilizer and the addition of a certain amount of organic fertilizer had no significant effect on cabbage yield and biomass. With the increase of organic fertilizer application, the transverse diameter of cabbage increased significantly. With the increase of specific gravity of organic fertilizer application, nitrate content gradually decreased from 26.3 mg/kg to 17.7 mg/kg, and nitrite content decreased from 0.86 mg/kg to 0.60 mg/kg. At the same time, the number of soil actinomycetes increased significantly to 300.99×10⁴ CFU/g, and the number of soil fungi decreased significantly to 149.99×10³ CFU/g. Reducing fertilizer application significantly increased the soil pH value, and the soil pH value increased to 7.03, which had no significant effect on the content of soil organic matter. Partial substitution of organic fertilizer for chemical fertilizer could meet the demand for fertilizer during cabbage growth. The cabbage treated with T50 could keep the yield and quality unchanged under the condition of 50% reduction of chemical fertilizer and at the same time improve the soil condition and the number of actinomycetes. It is a stable and reasonable fertilization mode for cabbage cultivation in winter fallow fields under the same conditions.

To provide technical support for the industrialized and large-scale production of tissue culture seedlings in the future, the effects of different seasons in southern Guangxi on the survival of transplanting of tissue culture seedlings of Primulina were discussed. In this paper, the effects of seasons on the survival of transplanting were studied using the group cultured seedlings of 17 species of Primulina. The survival differences of different species in the same season and the survival differences of the same species in four different seasons were analyzed. The results showed that most of species had higher survival rate when transplanted in spring, and the highest and lowest was P. tribracteata and P. crassirhizoma, respectively, with the survival rate of 100.0% and 51.3%. The suitable species for transplanting in spring were P. guigangensis, P. sclerophylla, P. yungfuensis, P. purpurea, P. tribracteata, P. glandulosa, P. glandaceistriata, P. liujiangensis, P. pungentisepala, P. macrorhiza. 17 species had lower survival rate in summer. The species with the highest and lowest survival rate was P. macrorhiza (68.7%) and P. lijiangensis (15.3%). Among the 17 species, more than half of them had higher survival rate when transplanted in autumn and winter. The highest survival rate of transplanting in autumn was for P. guihaiensis and P. napoensis, and the lowest survival rate was for P. glandaceistriata. Autumn was the best transplanting season for P. guihaiensis, P. crassirhizoma, P. Napoensis. In winter, the survival rate of P. hiemalis was the highest, and that of P. yungfuensis was the lowest. Winter was the best transplanting season for P. guizhongensis, P. atropurpurea, P. hiemalis, P. lijiangensis. The transplanting season of 17 species was the best in spring and the worst in summer. Different species have different suitable transplanting seasons, so it is necessary to transplant the appropriate species according to the seasons to ensure a higher survival rate.

The effects of different nursery measures on the growth performance of green budlings of Hevea brasiliensis were studied using ‘GT1’ seedlings as the rootstock planted in different periods, the clone ‘Yunyan 77-4’ ‘Yunyan 77-4’ and ‘GT1’ were used as the scions. Based on graft survival rate, budding rate, stem diameter and seedling height of saplings, the effects of sowing time, seedling age and topping method of rootstocks on the growth of grafted sapling with green budding method were systematically evaluated by the membership function method. Sowing time significantly or very significantly affected the graft survival rate and growth (P<0.05, P<0.01), while budding rate was not significantly affected. The optimal sowing time was different among three clones, ‘Yunyan 77-4’ and ‘Yunyan 77-2’ had the best grafting effect when sowed in the middle of October, and the comprehensive evaluation value was 2.33 and 2.30, respectively. ‘GT1’ showed best when sowed at the beginning of January of the following year, with a comprehensive evaluation value of 2.32. Seedling age very significantly affected the graft survival rate (P<0.01), while the other three indexes were not significantly affected. The best seedling age of the three clone varieties was 60 days after transplanting. The topping methods of rootstock had significant or very significant effect on the budding rate and seedling height (P<0.01), but had no significant effect on the budding survival rate and stem diameter (except ‘GT1’). The best topping method was bending first and then breaking, which was the same in all three clone varieties.

To explore the effect of grafting on the volatile compounds in red cherry tomato fruit, the volatile compounds and relative contents of grafted and non-grafted fruit of three red cherry tomato varieties were analyzed by headspace solid phase micro-extraction (HS-SPME) with gas chromatography-mass spectrometry (GC-MS). The results showed that there were 57 volatile compounds in CT18013S, including 5 unique compounds, of which heptanal was the main flavor compound. There were 69 volatile compounds in CT18013J, including 17 unique compounds, of which butyl acetate and guaiacol were the main flavor compounds. Fenxing S contained 52 volatile compounds, including 3 unique compounds. Fenxing J contained 60 volatile compounds, including 11 unique compounds, of which 1-nitro-2- phenylethane was the main flavor compound. Hongxing S contained 57 volatile compounds, including 6 unique compounds. Hongxing J contained 64 volatile compounds, including 13 unique compounds, of which heptanal, benzyl cyanide, 1-nitro-2-phenylethane and E,E-2,4-decadienal were the main flavor compounds. The comprehensive comparison results showed that the number of volatile flavor compounds were more in grafted fruit than non-grafted fruit in the three red cherry tomato varieties. Compared with non-grafted plants, grafting increased the contents of benzeneethanol, E-2-heptenal, benzeneacetaldehyde and nonanal in the grafted fruits of three red cherry tomato varieties. This study could provide scientific basis for further analysis of tomato flavor regulation.

This study aims to evaluate the pathogenicity of commercially available entomopathogenic nematodes against Aethina tumida larvae and pupa, thus develop a new agricultural method to control A. tumida beetle. The pathogenicity of 5 strains of entomopathogenic nematodes (EPNs) against wandering larvae and pupae of A. tumida were determined by the dipping and sand bioassays in the laboratory, respectively. In addition, the influence of different application time and dosage on the virulence of Steinernema carpocapsae All to A. tumida larvae was tested by sand bioassays under laboratory condition. The dipping bioassay results showed that the pathogenicity of 5 EPNs strains against A. tumida larvae was different under laboratory condition. The infection incubation of S. carpocapsae All against A. tumida larvae was the highest. The corrected mortality rate of A. tumida larvae infected by S. carpocapsae All were 67.50%±0.05% and 2.36%±3.14% after 4 d and 12 d, respectively, which was higher than that of other EPNs. The sand bioassay result demonstrated a significant treatment effect on A. tumida mortality when compared to the control. The S. carpocapsae All provided excellent control with 100% mortality of A. tumida larvae being obtained, which showed significantly higher mortality than A. tumida larvae exposed to any other nematode strains. Sequential applications of the nematodes following larvae entering sand also provided excellent control before 14 d application. The optimal control effect would be achieved when the ratio of S. carpocapsae All to A. tumida was more than 213∶1. So entomopathogenic nematodes S. carpocapsae All has a potential to control A. tumida larvae and pupae, it could be recommended for use in apiary where A. tumida occurred.

To effectively solve the problem of high incidence of Tapping Panel Dryness (TPD) in ‘93-114’ and further verify the prevention and control effect of rubber trees rehabilitation combination preparation, TPD was prevented and controlled by rubber trees TPD rehabilitation combination preparation. Field tests were carried out in 2015—2016 and 2016—2017 respectively. The tapping cut symptoms, the index of TPD and latex yield of TPD plants were observed before and after treatment. The mean recovery rate of TPD was 79.84%, which was 45.20% higher than that of the control. The reduction value of TPD length was 68.36, the control effect could reach 71.41%, and the average value of the two repeated tests was 59.34%. The latex yield of TPD plants increased significantly. The latex yield of the two repeated tests per plant per tapping was 204 g and 144 g respectively. Compared with the control, the latex yield of treated plants increased 1.68 times and 6.2 times. The TPD rehabilitation combination preparation and its matching application technology can significantly improve the tapping cutting symptoms of clone ‘93-114’ TPD plants, increase the yield of latex, and the prevention and control effect is significant. It is a relatively ideal rubber tree TPD control technology at present.

The occurrence of citrus tatter leaf disease and citrus leaf spot disease were investigated in the main planting areas of citrus in Nanning, Chongzuo, Liuzhou, Guilin, Yulin, Hechi, Hezhou, and Fangchenggang of Guangxi. RT-PCR detection, viral genome sequencing and genetic diversity analysis were carried out for the pathogenic viruses, including Citrus tatter leaf virus (CTLV), Apple stem grooving virus (ASGV), and Citrus leaf blotch virus (CLBV). The results showed that the detection rates of CTLV, ASGV, and CLBV in suspected viral samples collected from the citrus-producing areas in Nanning, Guilin, and Yulin was 21.2%, 28.6%, and 7.6%, respectively. Additionally, the mixed infection of multiple viruses was detected. Among the samples tested, the detection rate of CTLV was the highest (7.3%), followed by CLBV (5.5%), and ASGV (3.0%). The genetic diversity analysis and phylogenetic analysis were carried out by comparing the sequences of the three virus isolates cloned in this study with those of several representative viruses reported. The results demonstrated that both ASGV and CTLV isolates in China presented host correlation in the evolutionary relationship, while ASGV isolates in Japan showed a stronger association with geographical location. Still, the strains in South Korea and India did not show significant host or geographical location correlation. The isolates of ASGV and CTLV on citrus and apple presented a relationship with geographic location, while their isolates on pear showed no association with geographic location or host. Moreover, all strains of CLBV showed a distinct relationship with the host. It is the first time to report the occurrence of citrus tatter leaf disease and citrus leaf spot disease in Guangxi and the genetic diversity of their pathogenic viruses, which would provide a reference for the diagnosis and control of citrus virus diseases.

Root rot of avocado is one of the destructive diseases. The disease infects the root system of plants, causing serious black rot of roots, leading to the death of plants. The strain was isolated and purified from the roots of typical symptoms and identified by the pathogenicity test, morphological characteristics, and multi-loci (ITS, LSU, and COXⅡ) phylogenetic analyses methods. The result showed the root rot of avocado from Hainan was caused by Phytophthora cinnamomi. To clarify the biological characteristics and sensitivity to ten fungicides, the effects of different culture condition on the hypha growth of P. cinnamomi were determined, and the inhibitory activities of ten fungicides on P. cinnamomi were also studied. The results exhibited that PDA medium was the appropriate medium for hypha growth, the optimum temperature was 28 ℃, the suitable pH was 8, and continuous darkness condition was beneficial to hypha growth. The toxicity test showed that dimethomoph had the best inhibitory activity with EC₅₀ of 0.0929 μg/mL among the fungicides. The result could provide a theoretical basis for the field control of avocado root rot disease.

To explore the functional gene information in flowering Chinese cabbage (Brassica campestris L. ssp. Chinensis (L.) var. utilis Tsen et Lee) inoculated by soft rot disease, the transcriptome of flowering Chinese cabbage was sequenced by BGISEQ-500 high-throughput sequencing technology. The results showed that average obtained 47.27 M clean reads and the Q20 base was more than 95%. A total of 36 760 Unigene transcripts were detected, of which 35 327 were known and 1 433 were predicted. A total of 19 549 new transcripts were detected, the length of which was mainly between 300 and 2000 nt. Functional annotation results showed that 32 047 Unigene were annotated in NR database, among which Unigenes were annotated most on Brassica rapa ssp. Pekinensis. GO function was annotated with 12 588 Unigene. Kegg database was annotated with 18 583 Unigene, involving 137 metabolic pathways. A total of 21 776 differential expression genes (DEGs) were obtained, including 15 007 DEGs, 6 137 up-regulated genes and 8 870 down- regulated genes between the control and premorbid groups. There were 13 118 DEGs, 10 278 up-regulated genes and 2840 down-regulated genes between pre-onset and mid-onset. There were 11 293 DEGs, 1 790 up-regulated genes and 9503 down-regulated genes. Analysis of the DEGs Ven map showed that 5 110 genes were different in each group. Functional analysis of DEGs showed that the differentially expressed genes were involved in various life activities, such as ubiquitin degradation pathway, peroxisome pathway, photosynthetic carbon fixation pathway, glycolytic process pathway and so on. The results of this study would lay a foundation for further studies on the genome and molecular biology of resistance to soft rot of flowering Chinese cabbage.

Microalga Desmodesmus sp. QL96 was originally isolated from Tibet, China. Previous studies have shown that it is rich in protein. In this work, the primary cell compositions were determined, and proteins were extracted by the improved TCA-acetone method. The amino acid composition, antioxidant and antibacterial activity of the extracted proteins were analyzed. The results suggested that the mean protein content of the microalga was (56.65±3.76)%. The raw proteins were tested to contain 17 amino acids, including 7 essential amino acids which accounted for 26.86% of the total amino acids. The extracted proteins showed scavenging ability against free radical, with the half scavenging concentration (IC₅₀) of •OH and DPPH• being 0.18 and 7.88 mg/mL, respectively. Also, an inhibition against bacteria was demonstrated by the raw protein, with the minimum inhibitory concentration against Streptococcus pyogenes, Escherichia coli and Salmonella typhimurium being 1.56, 3.13, 1.56 mg/mL, respectively. This study could provide a basis and reference for the further development of functional proteins of Desmodesmus sp. QL96.

The method for the determination of pydiflumetofen and difenoconazole residues in banana fruit and flesh was established. The upervised residue trial was carried out in Yunnan. The residual digestion behavior and dietary intake risk in banana were analyzed. Average recoveries of pydiflumetofen and difenoconazole in banana fruit and flesh were found in the range of 75%-115% and 78%-106% at the three spiking levels from 0.01 to 1 mg/kg with relative standard deviations of 1.0%-5.0% and 1.0%-5.3%. The limit of quantification (LOQ) of instrument for pydiflumetofen and difenoconazole was 0.01 mg/kg. The results demonstrated that the half-life of pydiflumetofen and difenoconazole for banana was 16.9 d and 20.4 d in Yunnan, respectively. The residue of pydiflumetofen was <0.01 mg/kg and the maximum residue of difenoconazole in banana was 0.048 mg/kg sprayed after 21, 28, 35 d. Risk assessments indicated that the long-term dietary intake risk of pydiflumetofen and difenoconazole in banana was low and at a safe level. The method shows high accuracy, high sensitivity and good linearity. The experiments would provide scientific basis for evaluating the safety and rationality of using pydiflumetofen and difenoconazole in banana.

Areca seed and areca shell polyphenols were extracted using the ultrasonic assisted method with 75% ethanol as extraction solvent and purified by S-8 macropore resin. The inhibitory effect of polyphenol extracts from areca nut on α-glucosidase activity before and after purification was studied. The inhibitory type on α-glucosidase activity was determined by kinetic experiments, and the fluorescence spectrum and synchronous fluorescence spectrum of α-glucosidase with different concentrations of areca nut polyphenol extracts were analyzed. The results showed that the IC₅₀ of areca seed polyphenol extracts before and after purification was (0.34±0.12) and (0.33±0.10)μg/mL, respectively, and the IC₅₀ of areca shell polyphenol extracts before and after purification was (1.73±0.31) and (0.14±0.09)mg/mL, respectively, indicating that the inhibition on α-glucosidase activity was enhanced after purification of areca shell polyphenol extracts. Kinetic experiments showed that the inhibition of areca nut polyphenol extracts on α-glucosidase activity belonged to the mixed type of competition and non-competition. The fluorescence spectrum and synchronous fluorescence spectrum analysis showed that areca nut polyphenol extracts had quenching effect on the endogenous fluorescence of α-glucosidase, but had no effect on the conformation of α-glucosidase. In conclusion, areca seed and areca shell polyphenol extracts have good inhibitory effect on α-glucosidase activity, which could provide reference for the development of natural inhibitors of α-glucosidase.

To enhance the added value of jackfruit and enrich the varieties of fruit vinegar in the market, the fermentation process of jackfruit vinegar was optimized, and the aroma components in the finished products were analyzed. The effects of inoculation volume, fermentation temperature, ethanol concentration, and pH on the acetic acid production in jackfruit vinegar were firstly studied through single factor tests, and the optimal fermentation process was obtained by the response surface methodology with four factors and three levels. The results showed that the optimum fermentation parameters were determined as acetic acid bacteria inoculation volume of 11%, fermentation temperature of 32 ℃, ethanol concentration 5%, and initial pH 3.3. Under the conditions, the acetic acid content in the vinegar reached (44.20±0.41)g/L. The aroma components of jackfruit vinegar were determined by head space solid-phase microextraction (HS-SPME) combined with gas chromatography-mass spectrometry (GC-MS). A total of 67 aroma substances were identified from the jackfruit vinegar. The major aroma compounds were acetic acid (26.15%), isoamyl acetate (12.78%), isoamylol (11.01%), ethyl 2-phenylacetate (10.99%), phenylethyl alcohol (4.72%), decanoic acid (3.61%), benzaldehyde (3.34%), phenethyl acetate (3.12%), octanoic acid (3.08%), 3-methylbutanoic acid (1.31%), ethyl laurate (1.07%). Through the optimization of the fermentation process of jackfruit vinegar and the analysis of aroma components, a new type of fruit vinegar which conforms to the relevant national and industrial standards was prepared, and the aroma components in fruit vinegar were preliminarily identified.

To clarify the variation characteristics of aroma quality in postharvest passion fruit, headspace-solid phase microextraction (HS-SPME) combined with gas chromatography-mass spectrometry (GC-MS) was used to determine the main components and the contents in the fruit volatiles during storage at ambient temperature (25 ℃) and low tem-perature (6 ℃). The present study further analyzed the activity variation rule of key enzymes in ester metabolism pathway, such as lipoxygenase (LOX), alcohol acyltransferase (AAT), alcohol dehydrogenase (ADH) and hydroperoxide lyase (HPL). The results showed that the main aroma components in passion fruit juice were esters during storage at ambient and low temperatures, and their relative contents accounted for 40.00%-60.32% and 54.95%-69.27%, followed by alcohols and ketones. Furthermore, the main ester components with high relative contents were identified as ethyl butanoate, ethyl n-hexanoate, hexyl butyrate, ethyl acetate and hexyl hexanoate. During storage at ambient temperature, the relative content of esters in passion fruit peaked on 4^th day (60.32%) and decreased to 40.00% on 12^th day. However, this relative content peak appeared on 20^th day (69.27%) and remained 54.62%-69.27% within the whole storage period at low temperature. Above results indicated that high relative content of esters could be maintained by low temperature storage. The analyses on key enzymatic activities in ester metabolism pathway showed that little variation of LOX, AAT and HPL activities appeared in passion fruit juice during early storage period (0-10 d) at low temperature. The enzymes were active during late storage period. The activity peaks appeared later than those at ambient temperature storage, indicating that low temperature could effectively inhibit the activities of key enzymes in ester metabolism pathway. In addition, the relative contents of ester components were strongly correlated with the activities of LOX, AAT, ADH and HPL. This study would provide reference for quality maintenance and postharvest preservation of passion fruit.

To improve the utilization of coconut processing byproduct, peptides were obtained from coconut globulin using limited enzymatic hydrolysis technology and purified by Sephadex G-25 chromatography in this study. Then the selected coconut globulin peptides were reacted with ferrous to prepare peptides-ferrous chelate. The effects of hydrolysis degree, pH, time, ferrous ion concentration and temperature on the chelating ability of coconut globulin peptides were studied. Moreover, the chelating conditions were optimized using an orthogonal test. Results showed that both hydrolysis degree (14.71%) and ferrous chelating ratio (24.66%) were the highest when coconut globulin was hydrolyzed by alcalase and flavourzyme. There were three peptides peaks through Sephadex G-25 chromatography, of which the fraction C showed the highest chelating ability (28.67%). The result of the orthogonal test demonstrated that the optimum preparation conditions were peptide concentration 1.0 mg/mL, 40 ℃, 0.5 h, pH 7.0 and ferrous ion concentration 0.5 mg/mL, then the chelating ratio of coconut globulin peptides was 30.67%. The results of fluorescence spectroscopy and infrared spectroscopy indicated that coconut globulin peptide could chelate iron with amino groups, carboxyl groups and methylene groups. The results showed that it is feasible to prepare peptide-iron chelate using coconut globulin. Moreover, the coconut globulin peptide-iron chelate could be used as functional food ingredient to improve iron deficiency status.

By sampling the sediments in the upper, middle and lower reaches of the Meishe River wetland in Haikou City in April and September 2018, the temporal and spatial distribution characteristics of the chemical properties of the sediments were studied, and the heavy metal pollution was evaluated to provide scientific basis for the management and maintenance of wetland functions of Meishe River Wetland Park. The sediment of Meishe River was generally acidic with pH value of 6.58. The pH value of the downstream in April was significantly higher than that in the midstream, upstream I and upstream II, but there was no significant difference among sampling sections in September. The pH of the upstreamⅡin September was significantly higher than that in April, with an increase of 13.0%, while that of the downstream in September was significantly lower than that in April, with a decrease of 16.6%. In April, the content of organic carbon (SOC) in the downstream was significantly higher than that in other sampling sites. In September, the SOC of the upstream I and downstream was significantly higher than that of the upstream II and midstream. At the same time, there was a significant difference in the upstream I between the two sampling time, with a significant increase of 65.4% in September compared with April. The contents of total nitrogen (TN), total phosphorus (TP) and heavy metals copper (Cu), plumbum (Pb) and zinc (Zn) increased from the upstream to downstream. The content of TP in the midstream increased by 76.9% and the Cu contents decreased in the downstream by 13.0% in September compared with April. Correlation analysis showed that there was a significant positive correlation between pH and Cu and Zn contents, and SOC, TN and TP contents were significantly positively correlated with heavy metal contents (P<0.01). A comprehensive analysis of the pollution coefficient and potential risks of sediments revealed that Meishe River sediments are clean and have low potential risks. In summary, the Meishe River is lighter in eutrophication, generally not subject to major pollution, has a relatively high-quality environment, and has a silt composite agricultural standard. In addition, it is necessary to strengthen upstream water pollution control.

The flora and community species diversity of vascular plants of Castanopsis hystrix forest in Luhe were studied based on field work. A total of 122 vascular species, blonging to 58 families and 88 genera, were recorded. At the genera level and species level, the tropical elements were dominant. There were 40 species in the arbor layer, 76 species in the shrub layer and 48 species in the herb layer, accounting for 32.79%, 62.30% and 25.93% of the total sequencely. The species richness pattern of every layers of the community displayed: whole community>shrub layer>herb layer> arbor layer, the Shannon-Wiener index and Pielou index displayed : arbor layer>shrub layer. The community updated naturally well. The communities presented a succession trend of steady growth. The species diversity index of C. hystrix community in Luhe was lower than that in Rongxian of Guangxi, higher than that in Hua’an of Fujian and the artificial C. hystrix forest in Yulin of Guangxi, and most similar to that in Rongxian, which was also a secondary community.