The effects of different nitrogen forms on the growth, rhizosphere soil nutrients and soil enzyme activities of cassava variety Huanan 9 (SC9) were studied to provide theoretical basis for the scientific fertilization of cassava in Hunan Province. CK (no nitrogen fertilizer), T₁ (amide nitrogen-urea), T₂ (ammonium nitrogen-ammonium sulfate) and T₃ (nitrate nitrogen-calcium nitrate) were set in the study. The level of soil fertility was the same, and the application rate of nitrogen fertilizer was 180 kg/hm². Effects of different nitrogen forms on plant height, stem diameter, soil nutrients, soil enzyme activity, yield and quality of cassava were studied. Compared with CK, different nitrogen treatments improved plant height, stem diameter, yield and quality of cassava. T₂ had the highest plant height, stem diameter, yield, dry matter rate and starch content, which was significantly higher than that of CK by 13.51%, 32.24%, 61.72%, 6.44%, 19.86%. Nitrogen application changed the nutrient content of rhizosphere soil, and T₂ had the best effect on the nutrient content of cassava rhizosphere soil. The contents of soil organic matter and alkali-hydrolyzable nitrogen in T₂ were higher than those in the other treatments. The content of available potassium in T₂ was higher than that in other treatments at root formation stage and root expansion stage. Compared with CK, nitrogen application increased soil enzyme activity in cassava rhizosphere. With the passage of the growth period, urease activity increased gradually, sucrase activity decreased at first and then increased, catalase and nitrate reductase activity increased at first and then decreased. Among them, the soil sucrase activity in T₂ was the highest. Comprehensive analysis, in Hunan, the effects of different nitrogen forms on cassava growth and soil environment were different. Compared with CK, nitrogen application improved soil fertility, and then improved the growth of aboveground parts of cassava, thus improving the yield and quality of cassava. Among them, the application of ammonium nitrogen fertilizer is more beneficial to the growth and yield of cassava SC9.

Screening new sugarcane varieties with high light efficiency could guarantee the high-quality development and sugar safety. Chlorophyll fluorescence parameters were measured and calculated from Lake-model for 3 commercial varieties and 10 new varieties to investigate the sugarcane photosynthetic potential under cloudy and sunny day through the mechanism model of photosynthetic electron flux (J) response to light. The results showed that light energy balanced between photosynthetic election transport and regulated energy dissipation (Φ_NPQ) under low and high light, the appearance of increased non-regulated energy dissipation (Φ_NO) under middle light resulted from the different transition mode among each sugarcane varieties according to increasing photo active radiation (PAR) other than photo-damage. Compared with in sunny day, the initial light utilization rate (α_e) of all sugarcane varieties was significantly higher in cloudy day, but J showed sharp decrease at the same PAR level. RG16117 and RG 1997 exhibited the highest photo-quantum efficiency (Φ_II) in cloudy and sunny day respectively, which showed no significantly difference between RG16239 and RG1997 under high light. Φ_II of RG16239 was lower than ROC22 and RG1997 under low and middle light with the lowest Φ_NO, but the saturate PAR and maximum J were relatively high under high light. The photosynthetic electron transport capacity index (J_PT) based on the weight ratio of cloudy and sunny days in recent 5 years exposed as RG1997 (21.93)>ROC22 (21.43)>ROC16 (20.62)>RG16239 (20.27)>GL05136 (19.43)>RG11713 (19.30)>RG1462 (19.29)>RG14291 (19.03)>RG16117 (18.94)>RG1339 (18.93)>RG1876 (18.08)>RG1 (17.41)>RG11559 (16.84), which made RG1997 and RG16239 high light efficiency varieties.

In this study, 75% ethanol solution was used to prepare the total extracts of arecanut nut (ANE). Then different fractions of the extracts were prepared by fractionating with petroleum ether (PE-ANE), ethyl acetate (EAC-ANE), n-butanol (BU-ANE) and water (W-ANE) in turn. The inhibition of hypertension from ANE was determined by angiotensin converting enzyme (ACE) activity inhibition assay in vitro. The inhibitory was evaluated with the fraction displayingthe best ACE inhibitory activity by the enzyme kinetic method. In addition, the contents of total polyphenols, total sugar and total protein in each fraction of ANE were determined. The correlation between the contents of the compositions and ACE inhibitory activities was analyzed. Finally, phenoliccomponents in the four fractions were analyzed. The results showed that all the fractions of ANE at different polar parts exhibited ACE inhibitory activity, and EAC-ANE displayed the best. Enzyme kinetics tests showed that the inhibitory effect of EAC-ANE from tender areca on ACE was a mixed type of competitive inhibition and non-competitive inhibition. The correlation analysis showed that the IC₅₀ value of the ACE inhibitory activity of each polar part of ANE was significantly negatively correlated with the content of polyphenols and total sugar. And the absolute value of the correlation coefficient between the IC₅₀ value of ACE inhibitory activity and the polyphenol content reached a very strong correlation (r=-0.912). And a variety of polyphenol components such as catechin, L-epicatechin, procyanidin B₂, protocatechuic acid, and quercetin were identified in the four different polar parts, and the content of polyphenol components in EAC-ANE was the highest. In conclusion, ANE has a certain blood pressure lowering potential, and the ethyl acetate extraction site is the best, and the polyphenol content has a strong correlation with the ACE inhibitory activity of each extract. It can be preliminarily inferred that polyphenols may be the main substances that inhibit the activity of ACE in ANE.

In 2022, a stiff fruit disease was found on seedless litchi in Hainan, which was obviously different from the common litchi diseases in Hainan, such as anthracnose and acid rot. It mainly damaged young fruits. There was no significant change in the appearance of young fruits when the disease occurred. When the fruit was broad bean, the outer peel of the diseased fruit became darker, and the inner peel became irregularly brown after dissection. The fruit no longer expanded, forming fleshless stiff fruit, which was easy to cause serious economic losses. In this study, the pathogen of the disease was isolated, identified, invasion way and rapid detection techniques were studied. The pathogen was identified as Fusarium pernambucanum by morphological identification, ITS, RPB2 and TEF1 gene sequence analysis. The pericarp of seedless litchi fruit at young fruit stage was susceptible to pathogen invasion after being damaged by farming operations, wind, piercing-sucking insects, while the fruit surface was not diseased without wounds. The main invasion period of the pathogen was 3.2-4.8 mm in the longitudinal direction of the fruit. After the fruit was bigger than 9.8 mm, the probability of pathogen invasion gradually decreased. Based on the TUB gene sequence, the specific primers for rapid detection of F. pernambucanum were obtained, and a rapid and efficient molecular detection method based on ordinary PCR was constructed. The detection method is sensitive and efficient, and would provide support for early diagnosis and prevention of seedless litchi stiff fruit disease.

The volatile aroma composition is one of the important indexes for cocoa quality evaluation, and fermentation is the key process that affects the volatile aroma composition of cocoa. To reveal the pattern and differences of the volatile aroma components during cocoa bean fermentation with different genotypes, three types of cocoa (ZYP11-9, STS16, and ZYP6-11) were used as the test materials, and the headspace solid-phase micro-extraction gas chromatography-mass spectrometry (HS-SPME-GC/MS) was used to determine the volatile aroma components during 0-7 days fermentation of cocoa beans, and the relative contents of each component were calculated by peak area normalization. The results showed that a total of 32 volatile aroma compounds were identified during the fermentation of cocoa beans from the three genotypes, among which 9 consensus aroma compounds, including 2,3-butanediol, 2-heptanol, 2-pentanol, 3-methyl-1-butanol, phenylethyl alcohol, linalool, acetic acid, 3-hydroxy-2-butanone, and 2,3,5-trimethylpyrazine, showed significant differences in the relative contents during the fermentation of cocoa beans from different genotypes; PCA analysis showed that there was some correlation between the main aroma components and the aroma characteristics of the fermentation stage, in which 2,3-butanediol, acetic acid, linalool, 3-hydroxy-2-butanone were positively correlated with the aroma characteristics of cocoa beans fermentation stage, and the aroma substances such as 3-methyl-1-butanol, butanolactone, and acetophenone were negatively correlated with the aroma characteristics of the fermentation stage. Therefore, there are differences in the aroma composition and content changes during cocoa fermentation with different genotypes, and there is a correlation between the main aroma components and the fermentation stage, which would provide a reference basis for the breeding and application of high-quality cocoa new cultivars.

Banana is a tropical fruit rich in nutrients and has important economic value. It is also one of the four major fruits in South China. Banana is a typical climacteric fruit. The release of ethylene in banana after harvest could accelerate the ripening and senescence of banana during postharvest storage, which would affect the storage freshness and economic value of banana. Therefore, it is necessary to explore the technology of improving banana postharvest storage quality, thus providing theoretical basis for practical application. In this study, postharvest bananas were treated by UV-C irradiation, citric acid immersion and the combination treatment, respectively. The bananas were stored in the dark for 12 days at a temperature of (20±2)℃ and a humidity of 60%-70%, and randomly sampled on the 1st, 6th, 9th and 12th day for each treatment during the storage period. The effects of the three methods on postharvest banana storage quality were studied by measuring physiological and quality indexes, such as hardness, weight loss rate, titratable acid content, and soluble solid content. The results indicated that the treatment with UV-C irradiation at the dose of 3.96×10^–2KJ/m² and combined treatment (3.96×10^–2KJ/m² UV-C irradiation together with 2.0% citric acid soak) resulted in better freshness effects than that of citric acid treatment, showing that the decrease of fruit hardness was significantly inhibited, the increase of weight loss rate was delayed, the increase of soluble solid content and the decrease of titratable acidity content were inhibited, and the sugar-acid ratio were maintained. At the end of storage, UV-C irradiation and combined treatment increased the hardness of bananas by 9.09% and 13.63%, reduced weight loss by 22.00% and 11.43%, and decreased sugar-acid ratio by 40.00% and 42.30%, respectively, compared with the control group. In addition, UV-C irradiation and combined treatment effectively inhibited the decrease of flavonoids, phenols and vitamin C contents, and improved the DPPH free radical scavenging rate and antioxidant capacity. At the end of storage, UV-C irradiation and combined treatment increased the vitamin C contents of bananas by 0.82% and 1.27%, the total polyphenol contents by 25.92% and 41.65%, the total flavonoids contents by about 30.00%, and DPPH radical scavenging rate by 13.98% and 36.59%, respectively, compared with the control group. In conclusion, both UV-C irradiation and combined treatment can improve storage quality and prolong shelf life of postharvest bananas. Therefore, these two methods can be used as green, safe and effective post-harvest preservation technologies for bananas.

Five uninhabited islands in Lianjiang was researched in detail to plant resources by the methods of surveying typical sampling plots and transect lines. According to field investigation data and literature review, statistical analysis of the species composition of seed plants, distribution area types and ecological types by using floristic geography principle, then compared with the similarity coefficients of genura and geographic composition of the genura of seed plants in different regions, and explored the similarity of vascular plant species among the five uninhabited islands and the relationship with island spatial characteristics. The wild seed plants represented by 190 species, belonging to 165 genera in 64 families. The dominant families were Compositae and Poaceae. It was obvious that the plurimotypic families and larger families in terms of the numbers of genura and species in a dominant position, meanwhile in terms of the numbers of families, dominated by oligotypic families and monotypic families. Herbaceous (55.94%) and shrubs (23.27%) preponderated in the life form, trees and vines were at a disadvantage in terms of number, only accounted for 13.86% and 6.93% respectively. The floristic composition was intricate and varied, and in terms of tropical distribution type, with a high proportion of the family and genus levels, accounted for 90.24% and 68.03% respectively, among them the pan-tropical species accounted for 75.62% and 36.05% respectively, the temperate component only accounted for 9.76% and 31.97% respectively, the R/T values of tropical to temperate family was 9.25 while of genus was 2.13, showing that seed plant flora in the five uninhabited islands were of tropical and sub-tropical types, consistent with the subtropical geography of the islands, transitional from tropical to subtropical. In terms of geographical relationship, compared with the seed flora of four regions from south to north in China, the flora was closely related to six uninhabited islands in Pingtan with similar latitudes, the similarity coefficients of genura was 71.32%. The R/T value of five uninhabited islands in Lianjiang was 2.13, which was lower than that of the uninhabited islands in the nearshore Xiamen (4.23) and the six uninhabited islands in Pingtan (2.58), and higher than that of the five nonresidential coastal islands in Zhejiang (1.11) and the nine uninhabited islands in the Bohai Sea area (0.66). With the increase of latitude, there was a growing tendency on the temperate component at genus-level, while the tropical component was contrary to the former, and the larger the R/T value, the stronger the tropical nature. In terms of flora similarity, the similarities of species between each of the five uninhabited islands in Lianjiang were low, correlation analysis showed that similarity of vascular plant species among different islands was influenced by island edge and habitat diversity. As a whole, the plant species of the seed flora were diverse with a tropical and subtropical transitional nature, ancient plants were abundant, it was consistent with its geographic characteristics of the transition zone between the pan-arctic and palaeotropial flora.

Hainan is the southernmost litchi production area in China, but the problems of excessive nutrient input and soil degradation are serious, and the reasonable nutrient input standard is lacking. The study analyzed the current situation of litchi yield, nutrient management and soil fertility in the main producing areas of Hainan, based on the principle of nutrient balance, by quantifying the crop nutrient demand law and the reasonable nitrogen surplus level under the conditions, specifying the upper limit of litchi nutrient usage, proposing the reduction target of nitrogen, phosphorus and potassium nutrient inputs for litchi in Hainan, and analyzing the differences in nutrient management levels of different types of farmers and the impact on soil fertility. The upper limit of nitrogen, phosphorus and potassium dosage of litchi at different yield levels in Qiongshan region was 200 kg/hm², 100 kg/hm², and 260 kg/hm² (<10 t/hm²), 273 kg/hm², 136 kg/hm², 355 kg/hm² (10-20 t/hm²), 439 kg/hm², 220 kg/hm², 571 kg/hm² (20-42 t/hm²), respectively. The phenomenon of excessive fertilizer input of farmers was prominent, and the excess nutrient input was aggravated with the increase of management scale. 60%, 97% and 131% of small farmers, medium operators and large-scale operators were higher than the upper limit of nitrogen fertilizer input. Phosphorus input was 204%, 236%, 258% higher than the upper limit of input; potassium content was 70%, 101% and 119% higher than the upper limit. The fertilization intensity was also significantly higher than the national NPK fertilization level of 70.8%, 189.9%, 123.4%. The surplus of nitrogen, phosphorus and potassium in Hainan litchi orchard was 365 kg/hm², 377 kg/hm² and 542 kg/hm², respectively, and the nutrient use efficiency (NUE) was 34%, 21% and 27%, respectively. A lot of phosphorus was fixed and lost in the soil. There were significant differences in the nutrient management among different types of farmers. Only 1.2% of small farmers were in the range of high N output and low N surplus, while the middle and high operators were all in the range of high N surplus. Soil phosphorus accumulation and soil acidification were prominent problems in the litchi orchards, and 46% of the orchards had soil phosphorus content over 0.96 g/kg, which was at a relatively rich level. 94% of the orchards were acidic soil (pH 4.5-5.5), and 77% of the orchards had low soil quality index (IFI) comprehensive rating. For the current Hainan litchi nutrient inputs unreasonable and soil degradation, the quota system should be adopted and promoted as soon as possible, and the use efficiency of organic and chemical fertilizer should be greatly improved, so as to realize the sustainable development of litchi fruit industry.

In this paper, the seedlings of 27 inbred lines of bitter gourd with four leaves and one heart were used as materials. After pre-cultivated one day, the seedlings were subjected to 39 ℃ temperature stress. And the 27 germplasm resources were divided into three types: high heat resistance, medium heat resistance and heat sensitivity screened by the heat damage index (TDG) after 72 hours of high temperature stress. Among them, six inbred lines with different heat tolerance were selected to measure 12 morphological and physiological indexes subjected to 39 ℃ stress for 0 h and 48 h, respectively, including plant height (PH), stem diameter (SD), plant fresh matter (SFW) and dry matter (SDW) and leaf relative chlorophyll content (SPAD), electrical conductivity (REL), peroxidase activity (POD), catalase activity (CAT), superoxide dismutase activity (SOD), malondialdehyde content (MDA)), proline content (Pro) and soluble sugar content (SS). The comprehensive evaluation values were obtained by the principal component analysis of heat resistance coefficients (α) of 12 morphological and physiological indexes to evaluate heat resistance of the seedlings. The mathematical model of heat resistanc evaluation was established by the stepwise regression analysis to obtain the heat resistance evaluation index system of bitter gourd. According to TDG, among the 27 bitter gourd inbred lines, three were heat-resistant, 18 were medium-heat-resistant and six were heat-sensitive. A mathematical evaluation model of heat tolerance of bitter gourd was established using the stepwise regression equation, which is Y=–0.426+0.049X₁–0.011X₂–0.009X₃–0.018X₄. The established optimal regression equation was used to predict the heat resistance of the tested materials, and the predictive values were basically consistent with the comprehensive heat tolerance value. Therefore, the heat resistance coefficients of SFW (X₁), POD activity (X₂), CAT activity (X₃) and SS content (X₄) could rapidly and accurately estimate bitter gourd heat resistance and were suggested to be used as evaluation indexes for heat resistance of bitter gourd. In order to provide a basis for the breeding of new heat-resistant bitter gourd varieties in Hainan in summer season, the heat-resistant bitter gourd germplams were screened and a heat-resistant evaluation system was constructed.

Camellia oleifera is a unique oil plant of Theaceae, which has important ornamental value and economic value. With the intensive planting of Camellia, many diseases and pests occur. In addition, the delayed breeding of improved varieties seriously restricts the development of the Camellia industry. INDETERMINATE DOMAIN (IDD) family is a kind of conservative transcription factors in higher plants, which regulate the basic immune response of plants by mediating plant endogenous hormones. In order to identify the members of IDD gene family in C. oleifera, 29 members of CoIDD gene family were identified through the conserved domain of IDD gene family with reference to the whole genome information of C. oleifera, and further clarified the structure, physical and chemical properties, phylogenetic relationship, and sub cell localization of each gene. The CoIDD4 gene homologous to AtIDD4/5/6 was cloned by RT-PCR, and its physicochemical properties, expression mode and nuclear localization signal were clarified. At the same time, the types of cis acting elements in its promoter region were analyzed. The results showed that 29 CoIDD gene family members were divided into 4 subgroups, with average hydrophilicity coefficients less than 0, belonging to hydrophilic proteins, and subcellular localization was located in the nucleus; The full-length ORF frame cloned into CoIDD4 gene contained 1620 bp base and encoded 539 amino acids, which were mainly expressed in leaf and flower organs; The cis acting elements in the promoter region of the gene were mainly involved in light response and plant hormone response elements. In conclusion, this study identified 29 IDD gene family members in C. oleifera, among which CoIDD4 gene was closely related to AtIDD4/5/6. It is speculated that CoIDD4 gene may be involved in the process of hormone signal transduction and basic immune response regulation of C. oleifera, which would provide a theoretical basis for the functional analysis of IDD transcription factors in C. oleifera and provide a reference basis for the selection and molecular breeding of superior resistant varieties of C. oleifera.