Mango (Mangifera indica L.) is one of the major cash crops in the tropics and a typical respiratory leap fruit, whose ripening senescence is associated with ethylenee. AP2/ERF transcription factors are widely present in plants, and it is found that the transcription factors are involved in the signal transduction of endogenous ethylene synthesis in fruits, and are key genes in the ethylene signaling pathway, playing an important role in plant growth and development, response to adversity stress and storage and transportation. To investigate the effect of AP2/ERF transcription factor on post-harvest mango ripening and senescence, a MiERF2 gene of 915 bp in length, encoding 305 amino acids, was cloned by PCR using Guifei mango as the target of this study. The molecular formula of MiERF2 protein was C₁₄₄₉H₂₂₅₉N₄₃₃O₄₇₀S_11. The molecular weight was 33 618.16 Da, the total atomic number was 4622. The theoretical isoelectric point was 7.66, with 30 positively charged residues and 29 negatively charged residues. The protein was hydrophilic and structurally unstable. MiERF2 didn’t contain a signal peptide, didn’t contain a transmembrane region, and phosphorylation modification was mainly threonine. MiERF2 contained a conserved structural domain of AP2, the secondary structure was dominated by 66.12% of random curl, also contained 24.67% of α-helix, 1.32% of β-fold, 7.89% of the extended chain. Its three-dimensional structure model contained three β-fold and one α-helix, consistent with the characteristics of the AP2 structural domain. The results of motif analysis and multiple sequence matching indicated that MiERF2 protein belonged to the ERF subfamily. Phylogenetic analysis showed that the closest relative to MiERF2 was the pistachio PvERF109-like, which is also a member of the Lacertidae family. Onion subcellular localization results showed that MiERF2 was localized in the nucleus. Quantitative real-time fluorescence analysis showed that the expression of MiERF2 differed after 400 μg/mL ethephon treatment at different harvest maturity. In 60% maturity mango, the expression of MiERF2 in the treatment group peaked at 9 d and then was significantly lower than that in the control group. In 80% maturity mango, the expression of MiERF2 in the control group was significantly higher than that in the treatment group during storage, except for 18 d. It is suspected that this gene would play a negative regulatory role in ethylene regulation of fruit ripening. This study would provide a theoretical basis for revealing the regulatory role of ERF transcription factors in postharvest ripening and senescence of mango.

The hyperosmotic Ca²⁺ channel protein OSCA is crucial for controlling hyperosmotic stressors in plants. To understand the role of the OSCA gene family in tea plant response to drought stress, this study was conducted to identify the OSCA gene family based on the whole genome data of tea plant and analyze the gene and protein structures and promoter cis-acting element, and analyze the expression patterns of CsOSCAs in different tissues of tea plant, among different drought-resistant varieties and under drought stress. The results showed that the tea plants genome contained 12 members of the OSCA gene family, named CsOSCA1-CsOSCA12. The amino acid sequences encoded by the CsOSCAs were 667-831 bp in length, with protein molecular weight ranging from 76 630.55 kDa to 93 563.99 kDa and isoelectric points ranging from 6.15 to 9.33, containing 9-12 transmembrane structural domains, all containing the characteristic conserved structural domain DUF221, which could be divided into four subfamilies based on phylogenetic relationships. Ten CsOSCAs were localized to seven chromosomes of Camellia sinensis and two CsOSCAs were localized to the contig of unanchored chromosomes. The secondary structure of the CsOSCAs contained 32%-38% transmembrane structure and 60%-68% α-helix. The CsOSCAs were tissue expression specific, and CsOSCA2, CsOSCA3, CsOSCA11, and CsOSCA12 were significantly higher in the drought-sensitive variety CN98 than those in the other two drought-tolerant varieties. Nine genes were responded to PEG stress, among which CsOSCA2, CsOSCA3, CSOSCA5, CsOSCA8, CsOSCA10, and CsOSCA12 were strongly induced by drought stress. Six genes included drought-inducible response elements, and 11 genes contained abscisic acid response elements, according to further examination of the promoter cis-acting elements. It is hypothesized that the OSCA gene family of tea plants play an important role in the response to drought stress, and this study would provide a reference for the functional analysis and stress resistance of OSCA gene in tea plant.

The alkaloid content of different samples in different seasons and different developmental stages of MHLC of two tea varieties, Nongdao Yecha (MHLC) and Yunkang 10 (YK10) was determined by HPLC. Caffeine synthase 1 gene (TCS1) was cloned from the cDNA of tea plant by RT-PCR in different samples, and its expression level was analyzed. The results showed that MHLC was a natural tea germplasm resource with low caffeine and high theobromine. Theobromine content of MHLC in different seasons was greater than 23.00 mg/g, while the caffeine content was less than 4.00 mg/g. In addition, the accumulation of caffeine and theobromine in MHLC shoots was the highest, and the leaves at the same stage had higher caffeine and theobromine than stems, and the caffeine and theobromine in leaves and stems gradually decreased with the increase of maturity. Through gene cloning and quantitative analysis, it was found that MHLC had two TCS1 allelic variants: TCS1b (with only theobromine synthase activity) and TCS1d (with both theobromine and caffeine synthase activities). Among them, the high expression of TCS1b and the extremely low expression of TCS1d are likely to be the key reasons for MHLC high theobromine and low caffeine. This research would provide material for low-caffeine tea breeding and molecular basis for the efficient utilization of MHLC.

Virus disease is one of the most serious diseases in tomato production in Hainan, China. The small RNA deep sequencing data of tomato virome in Hainan revealed the presence of Southern tomato virus (STV) in samples from several regions, and a single STV infected sample was found. RT-PCR screening of 987 field samples with virus-like symptoms collected from 2015 to 2021, was carried out to determine the distribution of STV in Hainan province. Results indicated that STV was detected in 142 samples from nine regions, STV had existed in Hainan tomatoes as early as 2015, STV detection rate increased from 8.82% in 2015 to 22.45% in 2021, showing an upward trend year by year. The complete genome length of four isolates amplified using RT-PCR and RACE was identical, each consisting of 3446 nt. Two partially overlapping open reading frames (ORFs) presented in the positive-sense RNA strand, the 5′-proximal ORF (position 147-1280 nt) encoded a 377 amino acid (aa) peptide representing a potential coat protein (p42), the second ORF (position 1048-3336 nt) contained typical motifs for an RNA-dependent RNA polymerase (762 aa). The length of 5′ untranslated region (UTR) and 3′ UTR was 146 nt and 110 nt respectively. Paired comparison showed that the nucleotide similarity among four STV isolates was 99.86%-100.00%, the nucleotide similarities with other STV isolates available in GenBank were 98.45%-99.94%. In phylogenetic trees based on the complete genome of STV, eighty STV isolates were obviously divided into two groups (Group Ⅰ and Group Ⅱ). Group Ⅰ included Asian, American, European and African isolates. In group Ⅱ, except for one Asian isolate, the others were European isolates, and four Hainan isolates were divided into group Ⅰ. The grouping of STV isolates was related to geographical location, may not be related to the host. The regions with high genomic sequence variability between Hainan isolates and group Ⅰ isolates were 881-1061 nt and 1521-1721 nt, and the regions with high genomic sequence variability between Hainan isolate and group Ⅱ isolate were 2041-2241 nt and 2761-2921 nt. No recombination events were found between STV isolates. This is the first report of STV in Hainan Province. The findings of this study would provide an important basis for understanding the distribution and occurrence trends of STV in Hainan province and for the development of effective surveillance and control measure.

There are about 69 species of Mangifera in the world, and 8 species are mainly distributed in China. The long history of mango cultivation in China has resulted in many natural hybrids with local characteristics. In the process of continuous coordinated development with the environment, the appearance of mango, such as branches, leaves and fruits, has changed to some extent, but its pollen has formed unique morphological characteristics while maintaining genetic conservatism and stability. In order to further study the taxonomic significance of the pollen morphology of mango plants and clarify the phylogenetic relationship between mango natural hybrids, this study carried out palynological research and genetic relationship analysis on mango germplasm based on the microscopic characteristics of pollen, and observed the pollen morphology and pollen exine ornamentation of 32 mango materials from two species of mango using scanning electron microscopy. On this basis, cluster analysis was carried out on six quantitative characters of pollen. The results showed that the pollen of 32 the mango germplasms belonged to N3P4C5 type. The polar view was 3-split triangle, and the red view was nearly elliptical. There were three germination grooves, which almost reached both ends; There were differences in the shape and size of pollen, the width of germination ridge, pollen ornamentation, the density and size of pollen outer wall mesh among the materials. Stripes or reticular ornamentation and pits were all over the surface of pollen grains. Most mango pollen belongs to reticular ornamentation. Mesh shapes were diverse, mainly circular and long, with rough ridges. Mesh distribution density varied among different materials. According to the cluster analysis of quantitative characters such as pollen grain size, pollen morphology, germination ridge width, mesh size and mesh density, the 32 mango germplasms could be divided into three groups when the similarity distance was 15. Mango resources from Southeast Asia, such as Machesu M. indica, Siam Mango M. indica, Ren He Carabao M. indica, were clustered into one group in the pedigree map, showing certain regional characteristics; Yun Nan Tu Mango M. indica, Bruce Mango M. indica and Amemwins No.26 M. indica with narrow germination ridge were divided into one type; M. persiciformis, collected M. persiciformis and common domestic M. indica. cultivation species were grouped into one group. The original wild species, Bai Hua M. indica, was grouped with No.1 M. persiciformis, No.2 M. persiciformis, No.3 M. persiciformis, and No.4 M. persiciformis. The resource had the characteristics of primitive and wild types. This study would provide palynological basis for the classification, genetic relationship and evolution of mango pollen morphology.

Scientific evaluation of sugarcane germplasm resources can provide high quality parental materials for sugarcane cross breeding. In this study, seven phenotypic traits of 141 excellent sugarcane germplasm were evaluated for diversity using methods such as principal component analysis and cluster analysis. The variation coefficients of smut rate, cane yield, millable stalks, stalk weight and sucrose content were all greater than 10%, with the variation coefficients of smut rate being the largest at 67.21%. Correlation analysis showed that the cane yield was highly significantly positively correlated with plant height, stalk diameter, millable stalks and stalk weight, and the stalk diameter was highly significantly negatively correlated with millable stalks, and the sucrose content was highly significantly negatively correlated with smut rate. The results of principal component analysis showed that the cumulative contribution rate of 3 principal component factors was 74.725%, among which the first principal component was related to yield traits, the second principal component was related to stems and quality traits, the third principal component was related to disease traits and quality traits. Based on cluster analysis, the 141 sugarcane germplasm resources could be divided into 3 groups, among which group Ⅰ had the taller plants, highest yield and highest sucrose content, highest disease resistance, strong persisrence, and had excellent performance for all traits. Group Ⅱ had the smaller plants, lowest yield and lowest sucrose content, lowest disease resistance, poor persisrence, and had poor performance for all traits. Group Ⅲ had average performance for all traits. 60 germplasm resources were selected with excellent overall performance by principal compoment analysis results and cluster analysis results, among which ZZ153303, ZZ150505, ZZ165201 and ZZ151106 could be used as high sugar content parents, ZZ15710, ZZ160913, ZZ162026, ZZ112819, ZZ1415219, ZZ1510055, ZZ140802 and ZZ151106 could be used as highly resistant smut parents, ZZ134007, ZZ118607, ZZ167010, ZZ144101 and ZZ156615 could be used as high yield parents.

With the development of the aerospace industry, the method of combining traditional breeding technology with aerospace mutagenesis technology to achieve breeding goals has been widely recognized by breeding experts. The problems faced by the scale of the banana industry in Fujian make the breeding of new banana varieties an important issue. In the early stage of this study, Brazil banana was used as the female parent. On the basis of space mutation, through continuous cultivation, screening and observation, two materials with obvious differences in biological and morphological characteristics were selected. In order to identify the genetic specificity of the two independently bred aerospace banana materials, the ISSR molecular marker technology was used in this study to screen out two primers with good polymorphism from 30 primers to analyze the two aerospace banana materials and 18 existing banana varieties. A total of 17 clear DNA bands were amplified by the two primers screened, of which 13 were polymorphic bands, accounting for 76.47% of the total bands, showing a high polymorphism at the DNA molecular level of banana materials. Electrophoresis showed that, combined with ISSR primers UBC881 and UBC847, the two aerospace banana materials had specific amplification bands, which could be distinguished from the other 18 banana varieties. Cluster analysis results showed that the genetic similarity coefficients between the 20 banana germplasm materials ranged from 0.545 to 1.000, with an average of 0.905; when the genetic similarity coefficient was 0.960, there were obvious genetic differences between the two bred aerospace banana materials, and the two bred aerospace banana materials with the female parent, and with other 17 banana germplasms. The results of this study would provide a strong basis for the breeding and identification of new varieties of aerospace bananas.

This study was conducted to explore the cumulative demand of nitrogen, phosphorus and potassium in disease-free sugarcane original seedlings, and provide reference for the nutrient management in the process of field propagation of disease-free sugarcane original seedlings. The growth of the disease-free sugarcane original seedlings of Zhongtang No. 1 in 2020 and 2021 was investigated, and the biomass and contents of nitrogen, phosphorus and potassium in roots, stems and leaves at various growth stages were determined for further analysis of the accumulation, phase absorption and daily absorption rate of nitrogen, phosphorus and potassium. It took 6 to 7 months for disease-free sugarcane original seedlings to reach 15 stem nodes from temporary planting of seedlings to the best harvest of seed canes. From July, August to late September (stem 1 to 2), the growth of sugarcane stems was the fastest. The cumulative increase of dry matter was the fastest in stem 4 (late October to late November), and this is the key stage of biomass accumulation. During the whole growth period of the disease-free sugarcane original seedlings, the content and accumulation of each element from high to low were potassium > nitrogen > phosphorus. Among the organs of roots, stems and leaves, leaves and stems always had higher nitrogen, phosphorus and potassium contents. The accumulation of nitrogen, phosphorus and potassium was mainly stored in the leaves before the stem elongation stage 1, and then mainly stored in the stems. The nutrient uptake rates of nitrogen, phosphorus and potassium at the seedling stage and tillering stage was 24.84%, 26.18% and 27.74%, respectively, and it was 55.54%, 58.61% and 52.30% at the stem 1 to 3 (late July to late October), while 19.62%, 15.20% and 19.96% during stem 4 and 5 (late October to late December). Reasonable fertilization can be carried out according to the phase absorption of each element, thereby improving the quality and economic benefits of disease-free sugarcane seedlings production. The demands of nitrogen, phosphorus and potassium in the breeding process of disease-free sugarcane original seedlings were clarified, which would provide a reference for the scientific and reasonable fertilization in large-scale field propagation of disease-free sugarcane original seedlings in the future, and improving the efficiency of the propagation and nutrient utilization of disease-free original seedlings.

Field experiments were conducted to study the relationship between nitrogen source, nitrogen application rate and the interaction on the source-sink development during the whole growth period of sweetpotato Mingmenjinshi and its relationship with yield and quality. The results showed that nitrogen application increased the chlorophyll content and net-photosynthetic rate of sweetpotato at 70 to 110 days after planting, the number of storage root per plant, average storage root weight and yield, the content of soluble sugar, sucrose, soluble protein, polyphenols and vitamin C, and significantly decreased the content of starch. Under the same nitrogen source, at 30 to 120 days after planting, the fresh weight of stems and leaves increased significantly with the increase of nitrogen application; the average number of storage root per plant, the average weight of storage root and the average weight of storage root per plant increased first and decreased then with nitrogen application, and were the highest when the nitrogen application rate was 120 kg/hm²; T/R first decreased and then increased with the increase of nitrogen application rate, and was the lowest when the nitrogen application rate was 120 kg/hm²; and the number of storage root per plant and yield was the highest with nitrogen application of 120 kg/hm². Under the high-yield nitrogen application rate of 120 kg/hm², compared with amide nitrogen and nitrate nitrogen, ammonium nitrogen significantly increased chlorophyll content and net-photosynthetic rate at 70 to 110 days after planting; significantly increased the fresh weight of leaves and stems at 30 days after planting; significantly increased the number of storage root per plant at 30 to 120 days after planting; significantly increased the weight of storage root per plant at 60 to 120 days after planting. At harvest, ammonium nitrogen significantly increased the yield of commercial storage root by significantly increasing the number of storage root per plant, also significantly increased the content of soluble sugar, sucrose, soluble protein and vitamin C, and improved flavor quality.

Considering that the serious shortage of available silicon content in typical paddy soil of Hainan Island, it is urgent to make reasonable application of silicon fertilizer. In this study, paddy soils developed from five typical parent materials (basalt, marine sediments, fluvial alluvium, sand shale, and granite) in Hainan Island were selected to investigate the effect of silicon fertilizer application on rice in a field plot experiment. Rice yield, quality and the related physiological, biochemical and agronomic indicators under different silicon fertilizer treatments were analyzed. Results showed that compared with the blank control, the silicon fertilizer application in both T₂ and T₃ treatments significantly increased the rice yield and its related indicators such as the number of stem tillers and effective heads, seed rates, 1000-grain weight, root activity, chlorophyll and crude cellulose content relative to the control. Rice quality such as milled rice, chalkiness and amylose content also reached a good level. It is generally recommended that the optimal amounts of Si fertilizer application are 750-950 kg/hm² (available SiO₂: 187-238 kg/hm²) for basalt-developed paddy soil and 625-935 kg/hm² (available SiO₂: 156-234 kg/hm²) for granite-developed paddy soil, respectively. Meanwhile, compared with the control, the amount of silicon fertilizer application in T₂ and T₃ treatments significantly increased the number of tillers, root activity, chlorophyll and crude cellulose content in paddy soil developed from marine sediments, river alluvial and sand shale. Rice yield reached the highest and rice quality reached a good level in T₂ treatment, but rice yield and its related agronomic indicators did not increase significantly with the increasing of silicon fertilizer application (T₃), and even some indicators exhibited a downward trend. It is recommended that the optimal amounts of Si fertilizer application are 560 kg/hm² (140 kg/hm² of available SiO₂) for paddy soil developed from marine sediments and river alluvial sediments, and 750 kg/hm² of silicon fertilizer (187 kg/hm² of available SiO₂) for paddy soil developed from sandy shale, respectively. Thus, this study revealed the effect of silicon fertilizer application in typical paddy soil of Hainan Island, providing a scientific basis for formulating the standard of silicon fertilizer application as well as demonstrating and popularizing high efficiency silicon application technology and of rice in Hainan province.

The study was aimed to screen out the excellent tobacco germplasm resources which could be used in the field of scientific research, production and breeding. Conventional chemical composition and major alkaloids were tested, compared and clustered for 141 flue-cured tobacco, 18 burly tobacco and 6 cigar germplasm resources from China and abroad. Total sugar and reducing sugar contents were high in flue-cured tobacco germplasms, while total nitrogen, nicotine and potassium oxide were high in burley tobacco germplasms. Total alkaloid and nicotine content were the highest in flue-cured tobacco germplasm Zilaihuang 2243, and the content of cigar germplasm Dutch (ohio) was the lowest. The nicotine and nicotine conversion rates were the highest in the tobacco germplasm Pingbanliu, and those for tobacco germplasm Erxingzi and Burley11B was the lowest. The 165 accessions were divided into 4 groups for clustering analysis. Flue-cured tobacco germplasms were mainly concentrated in Group 1 and 4, characterized by high total and reducing sugar content and low nicotinic conversion rate. Group 2 was low in total and reducing sugars, and high in total nitrogen, total alkaloids and potassium oxide. Group 3 had low nicotinoids and total alkaloids, high nicotinic reduction, and high nicotinic conversion rate. The chemical composition and alkaloids of different germplasm resources have significant difference. The selected germplasms with different gradients could provide useful material for further study of nicotine.

In order to clarify the salt tolerance range of Morinda citrifolia seedlings and the effect of salt stress on the growth of M. citrifolia seedlings, the M. citrifolia seedlings cultured in water for 180 days were used as materials, and the basic medium was 1/8 MS liquid medium, in which NaCl with mass fractions of 0, 0.2%, 0.4%, 0.6%, 0.8% and 1.0% were added respectively for stress treatment. The results showed that with the increase of NaCl stress concentration and stress time, the relative water content (RWC) and biomass of M. citrifolia leaves gradually decreased, and the contents of soluble protein (SP), malondialdehyde (MDA) and the activities of superoxide dismutase (SOD), catalase (CAT), ascorbic acid peroxidase (APX) and peroxidase (POD) gradually increased first and then decreased. The protective enzyme activity of M. citrifolia seedlings changes significantly with the increase of NaCl stress concentration and the passage of stress time. In the range of NaCl concentration below 0.8%, M. citrifolia can reduce damage and ensure growth by regulating osmotic substances and antioxidant enzymes. When NaCl concentration is in the range of 0.8% or above, the protective enzyme system and cell membrane are seriously damaged, which affects the growth of M. citrifolia. Therefore, the seedlings of M. citrifolia can be tested in the area with NaCl concentration below 0.8%.

Nymphaea hybrid is a large tropical water lily in the genus Nymphaea. Different from the common water lily at present, N. hybrid has a long flowering period, beautiful flower shape, rich flower color, pleasant fragrance and rich biological active substances, which has attracted more and more attention. The flower color of different N. hybrid varies with the change of flowering stage, but the change rule of flower color is not clear yet. In this study, the outer petals of four different colors of N. hybrid flowers at different flowering stages were used as the test materials. The chroma value, anthocyanin, flavonoids, pH value of cell fluid, contents of soluble sugar (SS) and soluble protein (SP), and activities of phenylalanineammonialyase (PAL) and chalconeisomerase (CHI) enzymes were measured during the flowering process. The epidermal cells of most petals of the N. hybrid flower showed irregular folds and protrusions. The pigment of purple, pink and yellow N. hybrid flowers was mainly distributed in the upper and lower epidermal cells, while the pigment distribution was almost absent in white N. hybrid flower. With the progress of flowering period, the total anthocyanin (TA) content, PAL and CHI activity decreased, cell pH value increased gradually. The contents of total flavonoids (TF), soluble sugar and soluble protein increased first and then decreased, while petals lightness L^* increased, and there were significant differences among parameters at different flowering stages. Total anthocyanin in petals was negatively correlated with L^* and pH of cell fluid, but positively correlated with PAL and CHI enzyme activities. This study shows that the changes of flower color of N. hybrid are affected by multiple factors, and the presentation of flower color is related to the shape of petals and the position of anthocyanin distribution. The content of anthocyanin and flavonoids in petals directly affect the depth of flower color. The activities of PAL and CHI enzymes promote the formation of flower color of N. hybrid to a certain extent. Meanwhile, pH, soluble sugar, and soluble protein affect the formation and stability of the flower color of N. hybrid by participating in physiological metabolism during the flowering process, and then affect the change of flower color tone of N. hybrid.

The aim of the study is to estimate the effects of different mulching treatments on the photosynthetic characteristics of leaves, soil physical properties and yield of Amorphophallus muelleri intercropped in rubber plantations. Seven treatments (silver film, black film, white film, straw mat, thickened black film, microporous black film and no mulch (CK) were set up in this experiment. Photosynthetic characteristics of A. muelleri leaves at the three stages of head changing, corm and maturity were measured and analyzed. Net photosynthetic rate (P_n), stomatal conductance (G_s), transpiration rate (T_r), intercellular CO₂ concentration (C_i), electron transfer rate (ETR), physiological characteristics parameters including soluble protein (SP) content, soluble sugar (SS) content, chlorophyll (Chl) content, chlorophyll a/b (Chl a/b). soil in situ physical properties including soil moisture comtent (SMC), soil conductivity (SC), soil temperature (ST), and underground corm yield of A. muelleri were assayed. The photosynthetic parameters (P_n, G_s, T_r and ETR) of A. muelleri leaves increased by different plastic film mulching treatments at the same period. P_n, G_s and T_r of straw mat treatment at the head changing stage and expansion stage were significantly higher than those of the other treatments (P<0.05), the amplitude of the other treatments fluctuated irregularly and there were significant differences among them. At the mature stage, SP and Chl of A. muelleri leaves under different treatments were significantly higher than those under the control in the same period, and there was no significant difference among all treatments. In the same period, the SS and Chl a/b of A. muelleri leaves under different treatments were slightly different. The SS of each treatment at the maturity stage was significantly higher than that of the control, and the SS of the control at the three stages was the lowest, while the Chl a/b of e plastic film treatment at the maturity stage was not significantly different from that of the control. In the same period, SMC and SC by different plastic films were higher than those of the control. The water retention effect of thickened black film treatment was the best, the SC of microporous black film treatment in the expansion stage and straw mat treatment in the maturity stage were significantly the highest, but there was no significant difference in SMC and SC among other treatments. P_n, G_s, T_r, ETR, SP, and Chl of the same mulch treatment at different stages were all in the following order: head changing stage>expansion stage>maturity stage, while the SS and Chl a/b of each treatment were in the following order: maturity stage>expansion stage>head changing stage. According to the results of correlation analysis between all indexes and yield, except ST and yield were negatively correlated, other indexes were positively correlated with yield. Compared with the control, different plastic film mulches increased the yield of A. muelleri. Black mulching, straw mat and thickened black mulching treatments significantly increased the yield, while white mulching and microporous black mulching treatments did not significantly increased the yield. Therefore, silver plastic film, black plastic film, straw mat and thickened black plastic film are suitable choices for A. muelleri to increase the production and efficiency in practical production.

Natural rubber latex (NRL) is susceptible to spoilage, and current high ammonia preservation systems have serious contamination problems. In this study, NRL was preserved by thione derivative LS, and the preservation effect on NRL was investigated. The volatile fatty acid value (VFA No.) and viscosity value of LS-preserved fresh latex were relatively low, and the preservation effect of LS at 0.1% was better than that of 0.25% ammonia. LS-ammonia composite preservation was used to prepare low-ammonia concentrated natural rubber latex (CNRL), and CNRL could be preserved stably for 180 days by the dosage at 0.01%~0.05%. The preserved low-ammonia CNRL had low VFA No. and good stability, and all the indexes met the requirements of production. The stability of the preserved low ammonia CNRL was outstanding, and all the indexes met the current production application requirements. The LS-ammonia composite preserved low ammonia CNRL also had excellent physicochemical and film-forming properties, and the tensile strength and tear strength of the vulcanized film were generally better than those of the current high ammonia preserved CNRL vulcanized film. By infrared absorption spectroscopy, the structure of the preservative LS-ammonia composite preserved low ammonia CNRLvulcanized film did not change significantly; thermal analysis showed that the thermal stability of the vulcanized film was basically the same as that of the high ammonia CNRL film. In addition, the safety analysis showed that the LS-ammonia composite preserved low ammonia CNRL dry rubber film did not have potential toxic effects. There was no skin irritation reaction, and the safety was better. The preservative LS has excellent preservation effect on NRL, and the composite preservation preparation of low ammonia CNRL has good performance, which can be used in the production of a variety of pure rubber products, and at the same time, the low cost has a broad application prospect.

Rubber particles are important components in latex, and have important effects on latex stability, rubber biosynthesis and processing properties. However, the difference of rubber particle size and distribution among different germplasms and the annual changes have not been systematically studied. In this study, 486 wild and cultivated Hevea germplasm planted in National Rubber Germplasm Respository were selected, and the latex were collected monthly during the tapping period from 2020 to 2021. The average diameter (Da), intermediate diameter (Di), intermediate diameter/average diameter (Di/Da), particle size≤0.259 μm frequency and particle size≤0.197 μm frequency of rubber particles were analyzed and studied. Da varied from 0.313 μm to 0.439 μm, and the coefficient of variation (CV) was 0.008-0.206. Di varied 0.209-0.366 μm, and the CV was 0.009-0.235. Di/Da varied 58.3%-84.9%, and the CV was 0.015-0.123. particle size≤0.259 μm frequency varied 31.1%-61.8%, and the CV was 0.013-0.322; particle size≤0.197 μm frequency varied 17.6%-46.4%, and the CV was 0.018-0.588. The five indexes showed significant differences among germplasm, which were suitable to be latex characteristic index. The correlation analysis of the five indexes showed that the correlation coefficient of Di and Da was 0.781; The correlation coefficient of particle size≤0.259 μm frequency and particle size≤0.197 μm frequency was 0.976; The correlation between Di and Di/Da was higher than that of Da, and the correlation coefficient reached 0.814. Di was also more correlated with particle size≤0.259 μm frequency and particle size≤0.197 μm frequency than Da, and the correlation coefficient reached 0.520 and 0.632, indicating that Di had a stronger statistical significance. Annual changes of Da, Di and Di/Da showed some difference. Da in June, July, August, October and December was not significant, and September and November were lower than other months. Di was not significantly different in June, July, August, September, November and December, and just a little lower in October. Di/Da had no significant difference in June, August and September, increased in November and December, but declined obviously in July and October. Da, Di, Di/Da, ≤0.259 μm frequency, ≤0.197 μm frequency in each month were all significantly correlated with the annual average. However, correlation coefficient were higher between alternate monthly measurements (June, August, October; July, September, November; August, October, December) and the annual average, reaching more than 0.850. That can be used for future rubber particle size testing.

Guifei mango has bright color and sweet taste, which is deeply loved by consumers. However, the yield and economic benefits of this mango had been seriously affected due to a high fruit abortion rate. Forchlorfenuron (CPPU) is a swelling agent used in the mango industry of Hainan which can improve fruit setting rate, promote fruit enlargement and induce parthenocarpy. But, the abuse of CPPU resulted in a higher percentage of abnormal fruit, the decline of quality, stay-green after harvest and flavor change. To find a appropriate dosage, we compared the effects of CPPU spraying with different concentrations on the yield, quality, postharvest storage characteristics and incidence of disease in mango fruit. The experiment was carried out in a demonstration park of mango standardization production, Chinese Academy of Tropical Agricultural Sciences, Dongfang City, Hainan Province. The Guifei mango trees with healthy, consistent size and vigor were selected as the test material. The age of trees is about 12 years. And CPPU aqueous solutions of 10 mg/L, 20 mg/L and 60 mg/L were sprayed on 15, 25 and 35 days after full bloom, respectively. Distilled water was used as a blank treatment. Six trees were selected for each treatment (3 repetitions). The fruits were harvested at 78 days after flowering, then put into corrugated boxes to avoid damage. All the fruits were brought back to the laboratory and stored in a cold storage at (25±1)℃ and 80%-90% relative humidity (RH). Fruit color parameters (L^* value, a^* value, b^* value) and pericarp pigments (contents of total chlorophylls, anthocyanins and carotenoids) were measured during harvest and storage to evaluate the effect of CPPU on the fruit color. Fruit firmness and contents of soluble solid content (TSS), titratable acid (TA), vitamin C were measured to evaluate the effect of CPPU on inner quality, postharvest storage characteristics and fruit ripening of mango fruit. In addition, the effects of CPPU on yield, single fruit weight of parthenocarpic fruit/pollinated and fruit-shape index were also studied. Spraying 10 mg/L CPPU solution could significantly improve the average yield (45.73 kg), 34.03% higher than the control (34.12 kg). Spraying a CPPU solution of higher concentration (20 mg/L, 60 mg/L) had no obvious effect on yield increase, or even reduced the yield. Spraying 10 mg/L CPPU solution had little effect on the number of fruits per tree. But if spraying CPPU solution of 20 mg/L and 60 mg/L could significantly reduce the number of fruits per tree by 46.08% and 60.19% compared with the control. Spraying 60 mg/L CPPU solution had the most obvious effect, the single fruit weight of pollinated and parthenocarpic fruit increased by 28.48% and 117.25% respectively. Spraying CPPU solution could increase the fruit-shape index of mango, but there was no significant difference compared with the control. Spraying CPPU had a significant effect on the contents of chlorophyll, carotenoid and anthocyanin during maturation and ripening of mango. That fruits treated with CPPU had higher chlorophyll and carotenoid content, lower anthocyanin content, and showed a greener color. The chlorophyll content in a mango peel treated with 10 mg/L, 20 mg/L, 60 mg/L CPPU increased by 5.12%, 8.67%, 9.83% and 21.23%, 36.63%, 48.07% respectively during maturation and ripening compared with the control. And the increase of carotenoid content was more obvious treated with 60 mg/L CPPU than that treated with 10 mg/L and 20 mg/L, the carotenoid content increased 22.56% and 18.81% respectively during maturation and ripening compared with the control. Different from chlorophyll and carotenoids, the content of anthocyanins decreased gradually with the increase of CPPU concentration. The content of anthocyanins decreased by 8.94%, 13.62%, 18.30% and 13.83%, 16.19% and 17.58% respectively treated with 10 mg/L, 20 mg/L, 60 mg/L CPPU during maturation and ripening compared with the control. The process of mango fruits from green to yellow was delayed by CPPU spraying during storage. Spraying CPPU solution could increase fruit firmness and titratable acidity (TA) content, reduce soluble solids content (TSS) content and delay fruit ripening. The incidence rate of anthracnose and stem-end rot decreased after CPPU treated. But in all processing, only the fruits treated with CPPU in doses of 10 mg/L were normal during fruits coloring. In addition, spraying CPPU could prolong the storage time of mango fruits, 60 mg/L CPPU treatment could delay the ripening for 4 days. Spraying 10 mg/L CPPU on 15, 25 and 35 days after full bloom stage could increase fruit-shape index, promote fruit enlargement and increase the mango yield. At the same time, the postharvest fruit treated with 10 mg/L CPPU could delay fruit softening and ripening during storage, reduce the occurrence of postharvest diseases, prolong storage time. Nevertheless, the nutritional quality of fruit was also decreased during ripening with the fruit hardness increased and the TSS content decreased. Spraying higher concentration of CPPU solution (20 mg/L, 60mg/L) had no obvious effect on yield increase, or even reduced the yield. Therefore, we suggest that spraying 10 mg/L CPPU solution in mango production, which could improve the yield, prolong the storage time and ensure the postharvest fruit quality.

Biomass-derived porous carbon has drawn extensive attention in the microwave absorbing materials (MAMs) due to the advantages of extensive sources, low-cost, sustainability and tailorable structure. Aimtolight-weight biomass-derived MAMs with high attenuation capacity over wide frequency range, longan shell-based porous carbon material (LSPC) was prepared by activated carbonization by using different activators, namely phosphoric acid (H₃PO₄), potassium hydroxide (KOH) and zinc chloride (ZnCl₂). Influence of activation on the microstructure, morphology and microwave absorbing performance of resulted porous carbon materials were systematically investigated by applying X-ray diffraction, Raman spectroscopy, scanning electron microscopyvector network analyzer. Results indicate that activation induced more amorphous regions and defects, thus forming more heterogeneous interface and polarization centers conducing to the dielectric loss. Compared with LSPC with thick and smooth skeletons, activated LSPC materials showed hierarchical structures with different scale pores. While LSPC-H₃PO₄ exhibited thinner wall of pores and LSPC-ZnCl₂ showed smaller pores on the skeleton, LSPC-KOH depicted vertebra-like hierarchical structure. Activation improved the microwave absorbing performance, and LSPC-KOH showed the best microwave capacity, with minimum reflection loss of -43.57 dB, which was 2.03 times and 3.02 times higher than that of LSPC-H3PO4 and LSPC-ZnCl2, respectively. Moreover, activation broadened the effective absorption bandwidth of LSPC to varying degrees. Analysis of structure-associated electromagnetic loss behavior implies that hierarchical structure, dipolar/interfacial polarization and multiple reflection greatly contribute to the balanced impedance matching and attenuation capacity, thus improving the microwave absorption performance of activated LSPC materials.

A time-saving, efficient and environmentally friendly method for the preparation of soluble dietary fiber (SDF) from coffee peel with ultrasound-assisted low eutectic solvents (UAE-DESs) was established for the first time, and its process parameters were optimized by single-factor test and response surface test to further explore a new green method for the preparation of soluble dietary fiber from coffee peel. Eight choline chloride-based deep eutectic solvents were prepared as extraction solvents by the heating method and compared with the conventional water extraction method. The results showed that the deep eutectic solvent system with a 1∶2 molar ratio of choline chloride to urea prepared the highest yield of soluble dietary fiber from coffee peel at 10.10%±0.11%, which was significantly higher than that of the conventional water extraction method at 6.50%±0.22%. The effects of DES composition (molar ratio, water content, liquid-to-solid ratio) and ultrasonic treatment (ultrasonic power, ultrasonic time) on the yield of soluble dietary fiber from coffee peel were investigated by single-factor experiments. The response surface methodology (RSM) combined with Box-Behnken design (BBD) was used to optimize the soluble dietary fiber yield and investigate the effects of deep eutectic solvent water content, liquid-solid ratio, ultrasonic power and ultrasonic time on the yield of soluble dietary fiber. Based on the optimization results of RSM, the optimal preparation conditions were determined as follows: water content of deep eutectic solvent 39.91%, liquid-solid ratio 32.37 mL/g, ultrasonic power 305.20 W, and ultrasonic time 33.80 min. Under this condition, the maximum soluble dietary fiber yield of coffee peel was 10.74%±0.14%, which was close to the predicted soluble dietary fiber value of 10.80%. Therefore, as an efficient and non-polluting green solvent, deep eutectic solvent can be used for the preparation of soluble dietary fiber from coffee peel. The results of this study would provide new ideas and theoretical references for the preparation of soluble dietary fiber from coffee peel, and have potential applications in the value-added utilization of coffee by-products, the production of new high value-added products and the development of natural functional foods.

To further explore the molecular characteristics and pathogenicity of Sri Lankan cassava mosaic virus (SLCMV) isolates in China. Mosaic cassava leaves were detected, and the domestic SLCMV isolates full-length genomes of DNA-A and DNA-B were obtained by PCR amplification. It`s nucleic acid and amino acid sequence characteristics were analyzed by bioinformatics software. The infectious clones of strong and weak pathogenic isolates (SLCMV-Colombo and SLCMV-DG1922) were constructed. The DNA-A and DNA-B components of the two virulence isolates were recombined, and the pathogenicity differences of the two isolates were compared by tobacco (Nicotiana tabacum) inoculation. The results showed that SLCMV isolates belong to “Old World begomoviruses” encoding 8 open reading frames (ORFs) including the AV2 gene. It has a typical common region (CR), repeat sequence, TATA Box and TAATATT↓AC stem-loop structure of Geminiviruses, and 7-amino-acid are missing at the carboxyl terminal of Rep protein. Domestic SLCMV genome, coding and non-coding region sequences were 97.0%-100.0% similar to the isolates from Cambodia, Thailand and Vietnam, and 86.5%-98.6% similar to the early isolates from India and Sri Lanka. Coding region of DNA-B were 95.0%-97.6% similar to Indian cassava mosaic virus strain (ICMV), were less than 80.0% to the other 9 African cassava mosaic virus strains. Infection clone inoculation showed that the DNA-A (ColA) component of the strong virulent isolate SLCMV-Col played an important role in the typical mosaic symptoms of N. tabacum leaves, while the DNA-B (DG1922-B) of the domestic isolate could cooperate with Col-A to produce strong pathogenicity to tobacco plants. This study analyzed the whole genome structure of SLCMV in China, the infectious clone and its technology provide an important research basis for further pathogenesis research of SLCMV.

As an important tropical crop, Manihot esculenta Crantz is one of the top six global food crops and provides a staple food for nearly 700 million people worldwide. However, diseases caused by virus infection are a serious threat to the development of the cassava industry worldwide. Cassava mosaic disease (CMD) is one of the most threatening diseases, causing serious economic losses. Sri Lankan cassava mosaic virus (SLCMV) is one of the pathogens causing cassava mosaic disease. SLCMV is a typical two-component geminiviruses, and its genome consists of two circular components, DNA-A and DNA-B. Nonsense-mediated mRNA decay (NMD) is one of the major pathways of mRNA degradation in eukaryotic cells and a prevalent antiviral defense mechanism in eukaryotes. More and more studies have shown that NMD is not only an important mechanism for regulating mRNA quantity and quality in eukaryotes, but also degrades viral RNA as well as post transcriptional gene silencing (PTGS), which is a prevalent antiviral defense mechanism in eukaryotes. The mRNA decay process of NMD includes four processes: recognition of PTC, deadenylation, decapitation and final exonuclease degradation, and UPF1, PARN, DCP2 and XRN4 are the key proteins in these four processes, respectively. Viruses are specialized parasitic organisms that must escape or be resistant to degradation by host cells in order to successfully infect. Poly(A)-specific ribonuclease (PARN) is a key factor in the NMD signaling pathway. At present, the molecular mechanism of SLCMV resistance to host NMD is unclear. In this study, we will demonstrate that the silent suppressor AC4 encoded by SLCMV interacts with Arabidopsis PARN using yeast two-hybrid system and bimolecular fluorescence complementation (BiFC) experiments. It is hypothesized that the SLCMV AC4 protein may help the virus evade or tolerate degradation by the host cell by inhibiting the viral defense function of the host NMD through interaction with AtPARN. The results lay the foundation for elucidating the molecular mechanism by which cassava mosaic virus regulates the antiviral defense function of host NMD.

Sisal zebra disease is an infectious disease caused by Phytophthora nicotianae, causing symptoms such as leaf spot, stem rot and shaft rot in sisal, and it has a serious impact on the yield and quality of sisal fibre. At present, the integrated control strategy of sisal zebra disease is mainly based on agricultural control, and combining disease resistance breeding and chemical control. However, agricultural prevention and control measures have the shortcomings of high labor cost and uneven operation skills of workers, disease-resistance breeding technology is difficult and its cycle is long, and chemical control is affected by the waxy layer on sisal leaf surface, which makes it difficult for the liquid to adsorb, a large amount of drug application can also lead to the increase of pathogen resistance and environmental pollution easily. Therefore, it is particularly important to develop biocontrol bacteria resources for the prevention and control of sisal zebra disease, and enrich comprehensive prevention and control methods. In this study, P. nicotianae was used as the target pathogen bacteria. Two antagonistic bacteria, PpHyHNCJ2 and PpHyHNCJ5 were obtained by the five-point confrontation method and the mycelial growth inhibition rate was 85.92% and 83.10%. By observing the microscopic structure of P. nicotiana mycelia, it was found that strains PpHyHNCJ2 and PpHyHNCJ5 inhibited the growth of P. nicotiana mycelia, and it showed the phenomenon of mycelium enlargement and thickening, branching deformity and entangling. Based on cell morphology, physiological and biochemical reactions, and the alignment of 16S rDNA gene sequences, it was concluded that strains PpHyHNCJ2 and PpHyHNCJ5 were identified as Paenibacillus polymyxa. Further studies showed that both strains PpHyHNCJ2 and PpHyHNCJ5 had broad spectrum antagonism, and they could effectively inhibit the growth of 11 kinds of pathogens such as P. capsica, P. sojae, P. melonis, P. palmivora, P. vignae, Fusarium oxysporum, Aspergillus niger, Colletotrichum siamense and so on. In addition, strains PpHyHNCJ2 and PpHyHNCJ5 had the ability to dissolve organic phosphorus, inorganic phosphorus, potassium, nitrogen fixation and iron production, which could provide conditions for the good growth of crops. The results showed that the two biocontrol bacteria had big potential for sisal zebra disease control, and it could lay a foundation for the biological control of sisal zebra disease.

Camellia nitidissima belongs to the genus Camellia of theaceae and belongs to the first-level national protection plant, with high ornamental value and medicinal value. However, at present, there are few wild resources of C. nitidissima. It is necessary to find efficient artificial cultivation methods, rapidly propagate excellent C. nitidissima seedlings, and then greatly improve the yield of large-scale cultivation of C. nitidissima. Arbuscular mycorrhizal (AM) fungi can significantly promote plant growth and development, increase crop yield, and enhance plant stress and disease resistance. Inoculation of AM fungi into C. nitidissima has a positive effect on the cultivation of C. nitidissima. Since almost all AM fungal inoculation test involves the growth of mycorrhizal observation and infection rate determination, and AM infection situation observation methods available are not efficient. An efficient dyeing of AM fungi C. nitidissima was reported. In this study, the effects of five dyes (Sudan red Ⅳ, acid fuchsin, trypan blue, aniline blue and acetic acid ink) on AM fungi of healthy plant roots of C. nitidissima were investigated. The results showed that 5% acetic acid ink staining solution had the best staining effect. Mycelia, vesicles, spores and other structures of AM fungi in root cortex cells were clearly visible, and AM fungi could be clearly distinguished from other unknown fungi, and the root staining effect could be preserved for a long time. The mycelia and vesicles of AM fungi stained with Sudan red Ⅳ and acid fuchsin were not in obvious contrast with the background, and the preservation time of acid fuchsin staining was short, which was not conducive to observation. The dyeing effect of aniline blue and trypan blue was slightly inferior to acetic acid ink, and the price was expensive and the experimental cost was high. The last four dyes are suspected of causing cancer, and the long-term use has great potential safety risks to the health of operators. Acetic acid ink dyeing is simple, low toxicity, low cost and excellent dyeing effect. It is suitable for the staining and section observation of AM fungi in the roots of C. nitidissima. The results would provide new ideas for the future application of C. nitidissima mycorrhizal seedlings.