The study was aimed to clarify the changes in moisture content, fiber microstructure, and metabolites during the hot air drying process of areca nut, and to precisely regulate the drying time. This study focuses on areca nut and five models were used to fit the hot air drying curves of areca nut at different temperatures, and a betel nut drying kinetics model was established. At the same time, scanning electron microscopy, LC-MS were used to explore the changes in the microstructure and metabolites of areca nut during the drying process. The results showed that the drying curve of betel nut showed an exponential decrease, and the drying rate curve was divided into two stages: acceleration and deceleration. Temperature had a significant impact on the drying rate. The Page model fit the hot air drying curve of areca nut well, with a coefficient of determination R² above 0.98 and a RMSE in the range of 0.02-0.06. The difference between the predicted and true values of the model was not significant, and it could better reflect the water changes during the areca nut drying process. Microstructure analysis shows that the fiber layer of areca nut became dense and compact with increasing drying time, and the whitening treatment caused the fiber structure of areca nut to become loose. The texture results indicated that with the increase of drying time, the hardness and chewiness of areca nut increased, while the elasticity decreased. The differential metabolite results showed that the drying process affected organic acids, lipids, and lipid molecules by affecting the metabolism of amino acid, linoleic acid, central carbon, flavonoid biosynthesis, and phenylpropanoid biosynthesis. This study would enrich the basic research on areca nut processing and provide a theoretical basis for the selection of hot air drying time for areca nut.

Based on the panel data of 18 cities (counties) in Hainan, China from 2012 to 2022, combining the non-expected output super efficiency SBM model and Tobit regression mode, this paper analyzed the spatial and temporal evolution characteristics of agricultural eco-efficiency and influencing factors of agricultural ecological efficiency in cities (counties) of Hainan. From 2012 to 2022, the average agricultural eco-efficiency in Hainan showed obvious grading characteristics of central region>western region>eastern region. The agricultural eco-efficiency at the county scale of Hainan improved significantly year by year. The average agricultural eco-efficiency was 0.541, and the number of cities (counties) above the average value was 7. In terms of spatial change, the overall distribution characteristics of agricultural eco-efficiency were “spreading from the middle to the east and west”, and the distribution characteristics of full efficiency and high efficiency were block and chain. The cities (counties) with medium efficiency were distributed around the cities and counties with full efficiency and high efficiency. The trend lines in the north-south direction and the east-west direction showed the characteristics of inverted U-shape. The temporal and spatial evolution of agricultural eco-efficiency in Hainan at the provincial scale was influenced by several key factors, including the level of farmers’ income, intensity of agricultural mechanization, use of agricultural chemicals, and urbanization rate. At different regional scales, farmers’ income level was the main factor affecting agricultural eco-efficiency in the eastern region, while urbanization rate, intensity of agricultural chemical input use and farmland irrigation rate were the main factors affecting agricultural eco-efficiency in the central region. Urbanization rate, farmers’ income level, agricultural industrial structure, intensity of use of agricultural chemical inputs and farmland irrigation rate were the main factors affecting agricultural eco-efficiency in the western region. On the whole, the agricultural eco-efficiency of all cities (counties) in Hainan showed an upward trend, and there were some differences in the agricultural eco-efficiency among different regions. In the future, we should explore the priorities of agricultural development in different regions according to local conditions to effectively improve agricultural eco-efficiency.

Grapefruit of Guipuyou No. 1 planted in Guangxi has high and stable yield, and the flesh is juicy, suitably acidic and sweet. The widely targeted metabolisms of flesh was determined, the differential metabolites were screened and the metabolic pathway was analyzed to understand the difference of flesh composition at different maturity stages. A total of 529 metabolites were detected from grapefruit of Guipuyou No. 1, including 159 flavonoids, 64 Phenolic acids,64 amino acids and derivatives, 53 others (saccharides and alcohols, vitamin, others), 51 lipids, 40 lignans and coumarins,34 nucleotides and derivatives, 29 alkaloids, 28 organic acids, 5 terpenoids and 2 tannins. The differential metabolites at different maturity stages mainly included flavonoids, phenolic acids, amino acids and their derivatives, lipids, lignans and coumarins, and most of them were down-regulated. The down-regulated types of phenolic acids, amino acids and their derivatives, lipids and other types increased, and most of them showed a continuous downward trend with the increase of fruit ripeness. Most of the down-regulated flavonoids showed a sharp decline in the early stage of fruit ripening, and then increased in the late stage of fruit ripening. The types of down-regulated flavonoids first increased and then decreased, with the most in the middle stage of fruit ripening. The relative contents of synephrine, spermidine, betaine, shikimic acid were consistently decreasing. The relative content of limonin increased in the early stage of fruit ripening, and decreased significantly in the middle and late stage of fruit ripening. The most significant enrichment pathway of differential metabolites was flavonoid biosynthesis in the early stage of fruit ripening, but it was phenylpropanoid biosynthesis during the whole ripening process. The fruit of G₂ had the best taste, with soluble solids of 12% and solid-acid ratio of 23.24, which was suitable for fresh eating. However, phenolic acids such as caffeic acid and ferulic acid, flavonoids such as isoquercitrin and hyperoside decreased significantly during this period. There were many kinds of metabolites in the pulp of grapefruit of Guipuyou No. 1, which was rich in nutritional and functional components. The best picking time for fresh food is from late October to middle November. Fruits used for health care or medicinal purposes should be picked in advance according to the efficacy requirements. This study would provide a theoretical basis for the study on the nutritional and functional components of grapefruit of Guipuyou No.1, and provide a reference for the best harvest maturity of its different uses.

Plant peroxidase (POD) plays a role in plant development, hormone signaling, and stress response, but there are few research reports on the POD gene in mango. This study used mango genome data as a reference and employed bioinformatics methods to identify members of the POD gene family from multiple aspects, including protein characteristics, phylogenetic relationships, gene structure, promoter cis acting elements, and gene expression patterns. The expression patterns of POD gene family members under enhanced UV-B irradiation through transcriptome and quantitative real-time PCR (qPCR) experiments were analyzed. The mango POD (MiPOD) gene family had a total of 77 family members, and the genes were then mapped to 17 chromosomes and 2 scaffolds, encoding amino acids with a number of 206~500 aa, Stable proteins were accountted for the majority, most of them were hydrophilic proteins. Most MiPOD were predicted to localize in subcellular within chloroplasts, and classified into seven subgroups using phylogenetic analysis. The gene structure among members of the subgroup were similar. The results of collinearity analysis indicated that the proportion of MiPOD genes involved in segmental duplication was relatively high. It was speculated that it may be related to the expansion of the MiPOD family. The selection pressure analysis indicated that the K_a/K_s values of collinear genes were far less than 1, indicating that MiPODs may be mainly subjected to purifying selection during the evolutionary process. The MiPODs promoter region contained a large number of light responsive, hormone responsive, and stress responsive elements. MiPOD had different expression patterns, which may be related to its different protein functions. MiPOD exhibited different expression patterns during fruit growth and development under enhanced UV-B irradiation, with only MiPOD7 showing significant differences in expression levels among the highly expressed members. MiPOD7 expression levels were significantly higher than those of the control under UV-B stress, suggesting that it may play an important role in the response of mango fruit to UV-B stress. In summary, members of the MiPOD gene family may have evolved through segmental duplication and intron reduction patterns, and perform different functions by sensing different types of signals, thus forming different expression patterns. This research would lay the foundation for further studying the response mechanism of mango POD genes to different signals.

Lysophosphatidyl acyltransferase (LPAT), a key enzyme which controls the production of lysophosphatidic into phosphatidic, plays an important role in phospholipid biosynthesis in plants. Hevea brasiliensis is an important source for the production of natural rubber, which has an irreplaceable role in the fields of national defense, medical treatment, high-end products, and has high social and economic value. Cloning and analysis of HbLPAT2 in H. brasiliensis would provide scientific basis for further exploration of its phospholipid biosynthesis function and the effect of phospholipid on nature rubber. In this study HbLPAT2 was cloned from the latex of the H. brasiliensis by molecular biology techniques, and the bioinformatics analysis, expression analysis and subcellular localization analysis were performed. In this study, two key genes responsible for phospholipid biosynthesis in the HbLPAT gene family were successfully cloned from the latex of the H. brasiliensis, named HbLPAT2a and HbLPAT2b, the full length coding sequence of HbLPAT2a and HbLPAT2b genes was 1161 bp and 939 bp, encoding 386 and 312 amino acids. Both HbLPAT2a and HbLPAT2b contained a PLN02380 lysopyatidyl acyltransferase functional domain and contained a highly conserved NH(X)₄D motif; HbLPAT2a protein had 3 transmembrane domains, and HbLPAT2b protein had 1 transmembrane domain, both of which had no signal peptide, were hydrophilic proteins, and contained multiple phosphorylation sites. The subcellular localization analysis showed that both HbLPAT2a and HbLPAT2b proteins were located in the endoplasmic reticulum. In different organs, the highest expression level of HbLPAT2a and HbLPAT2b was found in seeds, suggesting that they have a lipid biosynthesis function. However, in the latex of H. brasiliensis, the first and second expression level of whole HbLPAT gene family were HbLPAT2a and HbLPA2b. The result is helpful to understanding that HbLPAT2a and HbLPAT2b play an important role in the phospholipid biosynthetic pathway in latex of H. brasiliensis and to providing a scientific basis for genetic improvement of latex quality of H. brasiliensis.

Vacuolar invertase (VIN), degrading sucrose to produce glucose and fructose irreversibly, is a key enzyme in soluble sugar metabolism, and involved in plant growth and development, yield and quality formation, and stress resistance. To investigate the physiological functions of VIN genes in soluble sugar metabolism of red pitaya (Hylocereus polyrhizus), HpVIN1 gene was cloned from the fruit, and sequence comparison, phylogenetic relationship, gene expression, subcellular localization, yeast growth complementation and sucrose degradation activity were analyzed. Based on RT-PCR (reverse transcription-polymerase chain reaction) amplification, the ORF (open reading frame) of HpVIN1 gene with a length of 1935 bp was isolated, which encoded 644 amino acids. Sequence analysis showed that HpVIN1 contained key domains related to sucrose degradation activity of invertase, as well as vacuole localization sequences in the N terminal. Phylogenetic analysis suggested that HpVIN1 was closely related to VIN genes from kiwifruit, loquat, apple and grape. Real time fluorescence quantitative PCR detection revealed that HpVIN1 was highly expressed in stems and fruits during the veraison stage (20~25 days after flowering), and weakly expressed in ripen fruits (30 days after flowering). The transient expression of HpVIN1 fused by green fluorescent protein in Arabidopsis thaliana mesophyll protoplasts demonstrated that HpVIN1 protein was localized in the tonoplast and vacuole. By over-expressing in the yeast strain with sucrose utilization defects, HpVIN1 could restore the yeast growth using sucrose as the sole carbon source, which proved that HpVIN1 had the sucrose degradation activity. In vitro catalytic experiment using the yeast total protein suggested that HpVIN1 could degrade sucrose into glucose and fructose. The sucrose degradation activity was the highest at pH 4.0, and rapidly decreased as pH value increasing. The results show that HpVIN1 that locates in the vacuole, has the enzyme activity of degrading sucrose to produce glucose and fructose, and participates in sucrose catabolism of stems and fruits during the veraison stage.

Papaya ringspot virus (PRSV) is one of the most serious diseases in papaya production, with high incidence rate, rapid transmission and serious harm. To detect papaya plants infected with PRSV in a timely manner, this study established methods for detecting papaya plants infected with PRSV using enzyme-linked immunosorbent assay (ELISA) and fluorescence quantitative reverse transcription PCR (qRT-PCR). The two methods were used to detect the PRSV content of multiple transgenic and non transgenic papaya plants, and the results were compared. The results showed that the standard curve established using PRSV peptide antigen as the standard and antibodies prepared from it had good fitting, and could be used for ELISA detection of PRSV; The reference gene Cpa03g018830 selected in qRT-PCR method was stably expressed at different growth stages of papaya and could be used as a reference gene for PRSV content determination; The detection results of PRSV content in multiple transgenic and non transgenic papaya plants using ELISA and qRT-PCR methods were basically consistent, indicating that both methods can be used for the detection of PRSV content in papaya plants. By using thee two detection methods, papaya plants infected with PRSV can be detected and eradicated in a timely manner, effectively preventing and controlling the spread of PRSV.

Phosphorus is one of the essential nutrients for plant growth, and plays a crucial role in determining crop yield and quality. Due to the combined pressure of decreased arable land quality and soil phosphorus deficiency or low bioavailability, the improvement of soil phosphorus availability has become a global concern. The rotation of two or more crops has positive effects on soil improvement, crop production efficiency and the restoration of agricultural ecosystem function. This study reviews the research progress on the effects of crop rotation on soil physiochemical properties, soil phosphorus transformation, and soil micro-food web. Firstly, the relationship between soil properties and phosphorus transformation is analyzed to assess the impact of crop rotation on phosphorus availability. Secondly, from the perspective of soil micro-food web and gene regulation, the transformation and biogeochemistry cycle of soil phosphorus was analyzed at the molecular level. It is summarized that crop rotation can affect soil phosphorus transformation through altering soil physiochemical properties and micro-food network structure, which can improve soil phosphorus availability, and ultimately promote crop yield and quality. We indicate that crop rotation is an important agricultural management measure for improving soil phosphorus availability. It is suggested to strengthen the related research and explore the combination model of crop rotation in the future. It would provide powerful support for food security and crop quality, and is of great significance in social economy and ecological environment.

Using the robusta coffee Reyan 1 as the scion and liberica coffee Chali 5 as the rootstock, grafting was carried out using the inarching method to investigate the effect of interspecies grafting on the growth of coffee grafted seedlings. Two sets of inarching methods were set up (cutting off the top of the rootstock first and then grafting, and grafting first and then cut off the top of the rootstock after surviving), and then transplanted into three types of soil (clay, loam, and sandy soil) and four different coffee continuous cropping years (0, 5, 10, 20 a) soil, and the robusta coffee self grafted seedlings were used as CK to study the effect of interspecific inarching on the survival rate, growth index, chlorophyll content, and growth and degradation of grafted seedlings in the different soil types and in the different coffee continuous cropping years soil. Results showed that grafting at the same stage of scion, the survival rate of F₂ treatment (grafted seedlings with preserved aboveground parts of the rootstock) was significantly higher than that of F₁ treatment (grafted seedlings without preserved aboveground parts of the rootstock). Using the same method, grafting at the “Butterfly” stage of the scion, the survival rate of grafting seeding was significantly reduced compared to grafting at the “soldier” stage. Different grafting methods could significantly affect the survival rate of coffee grafted seedlings, and the younger age of the scion seedlings was beneficial for improving the survival rate of grafted seedlings. The treatment of F₁ increased the root system, root to shoot ratio, and promoted the increase of aboveground biomass, resulting in faster plant growth. In the early stage of F₂ treatment, the biomass of the aboveground part was high, which promoted the growth of the underground part. Cutting off the top of the rootstock after surviving relatively reduced the biomass of the aboveground part, inhibited the growth of the root system, which reduced the biomass of the root system. Different soil types had a significant impact on the growth of the root system of grafted seedlings. In clay, the root system of robusta coffee seedlings was more developed than that of liberica coffee seedlings, while in sandy soil, the root system of liberica coffee seedlings was more developed than that of robusta coffee seedlings. As the grafted seedlings grew, if the root system of robusta coffee seeds was not cut off in time after grafting and surviving, the root system of liberica coffee seedings would slowly deteriorate with growth. In soils with different coffee continuous cropping years, the survival rate of interspecific inarching seedlings was 100%, significantly improving the survival rate, effectively alleviating continuous cropping obstacles, improving survival rate, and restoring aboveground growth. On the 2–3 days after grafting, the parenchyma cell in the cortex began to coalescent. On the 4th day, callus tissue could be seen between the rootstock and scion. On the 6–8 days, 2/3 of the stem segments between the rootstock and scion had already healed, and healing was evident on the 8–10 days. Using liberica coffee as rootstocks and robusta coffee as scions, the method of cutting off the top of liberica coffee seeding first and then inarching during the “soldier stage” of the scion can obtain vigorous interspecific grafting seedlings, which can effectively alleviate soil continuous cropping obstacles and improve coffee growth.

As an imported crop, date palm lacks planting management experience in China. It is imperative for the development of Chinese date palm industry to select suitable nutrients, construct the date palm rooting system quickly and efficiently, ensure the full absorption of nutrients by the roots during the field planting period, and shorten the growth cycle of date palm. In order to study the effects of different microalgae fertilizer on the growth of date palm seedlings of “Mabroom” and “Sillege” varieties, fresh microalgae (M₁), fermented microalgae solution (M₂), microalgae nutrient solution (M₃) and microalgae circulation solution (M₄) were selected to treat the seedlings. The growth and physiological indexes (leaf length, relative permeability of cell membrane, malondialdehyde MDA, peroxidase POD, catalase CAT, glutathione reductase GR) of date palm seedlings were measured. The results showed that the leaf length of “Mabroom” seedlings was significantly higher than that of the control group after treatment with microalgae nutrient solution (M₃) and microalgae circulation solution (M₄), and the microalgae nutrient solution (M₃) and microalgae circulation solution (M₄) could promote the growth of “Mabroom” seedlings. The osmotic regulation ability of leaf cells was strong. The contents of catalase, peroxidase and malondialdehyde were lower than those of the control. After treatment with fresh microalgae (M₁) and fermented microalgae solution (M₂), the leaf elongation length of “Sillege” seedlings was significantly higher than that of the control, and fresh microalgae (M₁) and fermented microalgae solution (M₂) were more suitable for the growth of “Sillege” seedlings, with fresh microalgae (M₁)>fermented microalgae solution (M₂). The osmotic regulation ability of leaf cells was higher than that of the control. The change of catalase content was lower than that of the control. This study showed that during the cultivation of microalgae, the microalgae nutrient solution (M₃) and microalgae circulation solution (M₄) could synthesize related active substances to produce primary metabolites. Such bioactive substances were absorbed by seedling roots and promoted the elongation and growth of date palm leaves. The “Mabroom” seedlings were more suitable to apply the secondary metabolites of microalgae as fertilizer. “Sillege” date palm seedlings are more suitable for fresh and fermented microalgae.