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.

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.

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.

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.

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.

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.

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.

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.

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.

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.