At present, the difficulty and pain point that sugarcane mechanical harvesting cannot be widely promoted is that mechanical rolling has a negative effect on sugarcane growth. In order to explore the effects of mechanical harvesting on the main agronomic traits and important physiological indexes of GT47 and GT31 at seedling stage, and provide theoretical reference for the evaluation of physiological adaptability of sugarcane mechanical harvesting and selection of suitable mechanical harvesting varieties, a randomized block design was used to compare and analyze the differences of plant growth rate, tiller rate, main components of leaves, root activity and related enzymes between mechanical and artificial harvesting treatments. The results showed that mechanical harvesting had a great effect on the rate of plant initiation and tillering of GT31, but not on the rate of plant initiation of GT47. There was a significant difference in nitrogen content between the two varieties during artificial harvesting, and the two harvesting methods had no obvious effect on the nitrogen content of GT47. The difference of total P content between GT47 and GT31 was extremely significant in artificial harvest, while there was no significant difference in total P content between the two varieties in mechanical harvest. Potassium content was greatly affected by different fertilization methods and different sugarcane varieties, and there was a significant difference in total potassium content between GT47 and GT31 regardless of mechanical or artificial harvesting. The root activity of GT47 and GT31 was 0.53 mg/(g·h) and 0.82 mg/(g·h) respectively in mechanical harvesting, but there was no significant difference in the root activity of the two varieties in artificial harvesting. After mechanical milling, the MDA content of GT31 root was significantly higher than that of artificial harvesting, while the MDA content of GT47 root showed no significant difference between the two harvesting methods. The CAT activity in root system of GT47 was 688.07 nmol/(min·g), which was significantly higher than that of GT31. There was no significant difference in Pro content and POD activity in roots among different varieties and different harvesting methods of the same variety. The adaptability of different sugarcane varieties in different harvest way differed. GT47 responded more quickly in tillering and other agronomic traits, and leaf nutrition, root activity, root art related enzymes after mechanical compaction. GT47 is more suitable for mechanical harvest.

Centromea pubescens is an important tropical leguminous forage. It is of great significance to study the salt tolerance mechanism of the plant for breeding excellent varieties and improving forage yield. In order to study the difference of salt tolerance of different seeds of C. pubescens in the germination period, the salt tolerance of 75 germplasms was identified in the germination period. NaCl with 150 mmol/L, and 14 indexes such as germination rate, germination potential, root length, bud length and fresh weight were measured, and membership function, principal component analysis, correlation analysis and cluster analysis were carried out to comprehensively evaluate the salt tolerance of germplasm resources of pteromea and to screening salt tolerant germplasm. Under salt stress concentration of 150 mmol/L, the coefficient of variation of relative root shoot ratio was the highest (67.75%), which could be used as one of the evaluation indicators of salt tolerance. The correlation analysis showed that there was a very significant (P<0.01) relationship between any two germination indicators of the germination rate and germination potential, and the other indicators were related to each other to a certain extent. Four principal component as the main component analysis of the direction of the cumulative contribution rate of 83.17% could replace most of the information of all indicators, comprehensively reflecting the germination characteristics during germination under salt stress, and determine the germination index, relative root shoot ratio, relative germination rate and root shoot ratio as the evaluation indicators of salt tolerance through the load matrix. The average membership function and comprehensive score were comprehensively evaluated for salt tolerance, and the 75 germplasm resources were divided into four categories by clustering based on the comprehensive score value of salt tolerance (Z), including 1 highly salt tolerant germplasm (Centrosema 050321057), 17 salt tolerant germplasm, 7 low salt tolerant germplasm and 50 salt sensitive germplasm. In this study, the salt tolerance evaluation system and material evaluation and screening methods were established, which could provide a basis for the study of salt tolerance and salt tolerance gene screening of the genus.

Morinda officinalis How is a plant of the Rubiaceae, whose dried roots are used as medicine It can strengthen bones and muscles, nourish kidney-yang and remove wind and moisture. It is mainly distributed in Guangdong, Guangxi, Fujian and Hainan provinces. It is one of the four major southern medicines in China. In the main production areas of China, it is mainly propagated by cuttings. In the process of variety breeding, it is often disturbed by plant viruses. The viruses are transmitted and accumulated in plants through asexual propagation of plants, resulting in the inhibition of plant growth and the decline of yield and quality. Therefore, for the purpose of tissue culture detoxification of M. officinalis, the tissue culture detoxification research of M. officinalis was carried out. Thereby improving the yield and quality of M. officinalis, which is beneficial to the protection of M. officinalis species. It is of great practical significance to provide technical support for quality resources and the factory-based seedlings of M. officinalis. Using the stem segments as the explants, an efficient and stable M. officinalis tissue rapid propagation system was established, and suitable plant regeneration methods were screened out. Using 1/2MS as the basic medium, M. officinalis stem axillary buds were used to induce clustered buds to obtain the virus-free seedlings and successfully domesticated and transplanted, the virus detection of M. officinalis tissue culture seedlings and transplanted seedlings were carried out by PCR technology. The semi-lignified stem segments as the explants were suitable to induce axillary buds, the most suitable medium was 1/2MS+6-BA 0.2 mg/L, and the axillary bud induction rate was 70%. Taking the axillary buds to induce fascicled bud, the most suitable medium was 1/2MS+6-BA 0.2 mg/L, and the fascicled bud induction rate was 86.36%. The suitable medium for rooting was 1/2MS+IBA 0.5 mg/L, with a root rate of 100%. The tissue culture seedlings were transplanted in the 1∶1 peat soil-perlite matrix for 8 days with the highest survival rate, reaching 93.3%. The reverse transcript PCR was used to determine the Cucumber mosaic virus isolate M. officinalis How (CMVMO) in the tissue cultured seedlings and transplanted seedlings, the plantlets of M. officinalis How detoxified was obtained. In this study, virus-free seedlings of M. officinalis were successfully cultivated through direct organogenesis, and an in vitro rapid propagation and regeneration system of M. officinalis was established, which would not only improve the yield and quality of M. officinalis, but also provide a reference for virus-free rapid propagation and commercial production and seedling raising of M. officinalis.

Hippeastrum is a new kind of flower introduced in large scale from abroad in recent years, but its seedlings are expensive, regular scale cuttage propagation speed is slow and needs a large number of mother bulbs. Cross breeding, a common method for its new varieties, however, has poor orientation. This aim of this study was to establish an efficient callus regeneration system for rapid propagation and factory production of seedlings, which can also be used for the orientation breeding of Hippeastrum. The effects about different plant growth regulators on callus induction and plantlet regeneration were studied with the leaves of Hippeastrum 'Bankkok Rose' plantlet in vitro. The highest induction rate of callus (39.67%) was observed when the basal leaves of the buds in vitro were cultured on MS+2,4-D 2.00 mg/L+TDZ 0.50 mg/L medium for 45 days. The optimal medium for callus proliferation was MS+6-BA 2.00 mg/L, and the average proliferation was 4.01 times every 20 days. The optimal medium for callus differentiation was MS+ KT 0.50 mg/L. After 60 days, the adventitious bud differentiation coefficient reached 10.59, and the seedling formation coefficient was 5.67. The rooting rate reached 100% after 30 days in MS+IBA 0.50 mg/L. After 30 days of root culture, the small plants were transplanted to the coir: peat soil: vermiculite =1 : 1 : 1 substrate, and the survival rate reached 93.33% after 30 days. This study could provide technical support for industrial propagation of Hippeastrum seedlings, and also provide excellent receptor materials for subsequent molecular breeding.

The southern ecological type of Chinese yam variety Guihuai5 was used to investigate the mutagenic effect of ⁶⁰Co-γ radiation. In a certain dose range, ⁶⁰Co-γ radiation had highly significant inhibitory effect on the germination and seedling growth of Chinese yam bulbils. The linear regression equation between the radiation dose and germination rate was y =-0.8776x+103.37. According to this, the half-lethal-dose and 40%-lethal-dose was 60.8 Gy and 72.2 Gy respectively. 40 Gy radiation treatment had no inhibitory effect on the germination, growth and development of the M₁ generation population of the bulbils. On the contrary, it showed a promoting effect in some extent. Radiation treatment induced increased tuber length, diameter and weight in the off spring plants of M₁ generation. The radiation treatment induced fascicular branching in some individual tubers in the M₁ generation, which resulted in the tuber change from long-column-shaped shape to irregular-block-shaped shape, and the weight of single tuber increased greatly. This occurred particularly in 90% of the plants harvested in the 100 Gy treatment. ⁶⁰Co- γ treatment induced mutations with twin tubers in the M₁ generation of the treated bulbils. The occurrence probability of the twin mutation was the highest in the 60 Gy treatment, accounting for 8% of the plants harvested. From the M₁ generation, 18 mutants with twin tubers, 11 mutants with large tubers and 1 mutant with female flowers were obtained. The results of this experiment indicate a bright prospect for radiation induction breeding of Chinese yam, and would provide basic materials for the further breeding of new Chinese yam varieties and lines.

To effectively monitor the occurrence and damage of dangerous pests in Zhaoshu Island, a systematic survey and risk assessment on all the pests of 90 plants in Zhaoshu Island was conducted. The results showed that there were 19 insects and mintes of 8 wild halophytes including 5 alien invasive pests and 7 world dangerous pests occurred and harmed seriously; 24 insects and mintes of 29 landscape plants including 9 alien invasive pests and 6 world dangerous pests occurred and harmed seriously; 36 insects and mintes of 31 salt-tolerant fruits and vegetables including 7 alien invasive pests and 6 world dangerous pests occurred and harmed seriously; 16 insects and mintes of 22 sand-bander plants including 5 alien invasive pests and 2 world dangerous pests occurred and harmed seriously. The results of risk assessment showed that Brontispa longissima, Paracoccus marginatus, Phenacoccus solenopsis and Opisina arenosella were all high-risk pests in Zhaoshu Island with R value 2.12, 2.12, 2.09 and 2.02, while Dysmicoccu neobrevipes, Diaspis boisduvalii, Tetranychus urticae, Thrips palmi, Bemisia tabaci, Liriomyza sativae and Bactrocera cucuribita were all moderate risk pests in Zhaoshu Island with R value 1.92, 1.89, 1.82, 1.79, 1.79, 1.74 and 1.61, respectively. The results were the first report on the occurrence and damage of plant pests in Zhaoshu Islan, which would provide an important basic information support for the effective protection of the biosafety in Zhaoshu Island.

C. camphora (L.) Presl is the most effective plant for extracting natural borneol in China. In order to help determine its proper habitat, this research plans to select branches and leaves of C. camphora (L.) Presl from eight habitats in China according to its habits, natural borneol of the leaves and branches of C. camphora (L.) Presl were extracted by steam distillation. The relative content of the chemical components in the extract was determined by GC-MS. The bacteriostatic circle diameter of Escherichia coli, Salmonella typhi and Salmonella enteritidis subsp was measured by the paper method, the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were determined by 96 micro well plates. Chemical composition determination showed that the content of natural borneol extracted from the branches and leaves from different habitats was different, among them, d-borneol, camphor, d-limonene, eucalyptol, d-α-pinene, camphene, α-humulene and terpinen-4-ol were the common components, and the content of d-borneol was the highest, then camphor. The highest content of d-borneol was found from Yuan'an, Hubei, China (82.47%), and the lowest content was found from Ruyuan, Guangdong, China (41.63%). The natural borneol extracted from various habitats showed bacteriostatic effect on the three tested strains, and the diameter range of bacteriostatic ring was 14.60 to 27.95 mm, the minimum inhibitory concentration (MIC) ranged from 250 to 1250 μg/mL, the minimum bactericidal concentration (MBC) ranged from 0 to 1000 μg/mL. The natural borneol from Yuan'an and Jishui, Jiangxi had the best bacteriostatic effect, while that from Guangdong had the worst on the whole. In conclusion, the bacteriostatic activity of the extracts from the branches and leaves of C. camphora (L.) Presl is correlated with the content of its main components, and the habitat with the highest content of d-bornol has the best bacteriostatic effect, while the other has poor bacteriostatic effect. The data obtained in this research are accurate and reliable, and would provide a basis for the quality evaluation of the extracts of C. camphora (L.) Presl branches and leaves and the development of natural borneol resources.

Paurocephala sauteri, characterized by small individuals, rapid reproduction and overlapped generations, is the most damaging pest of mulberry trees in tropical and subtropical areas. It happens in seedling period, leading to yield loss over 40%, or even out of harvest, and is very difficult to control. In order to accurately predict and efficiently control the pest, and to improve the yield and quality of mulberry leaves, the internal reproductive system of the male and female adults of the pest in different developmental periods was dissected and observed to clarify the morphological characteristics and changes of the internal reproductive system of male and female adults of the pest before and after mating. Except for 2 pairs of lateral oviducts the composition of the internal reproductive system of the female adults is similar to Trioza erytreae (Del guercio), and male adults is highly similar to Diaphorina citri (Kuwayama). Compared with the pre-mating period, the length of spermatheca in mating and post-mating periods reached nearly 1.63 times and 1.85 times, and the width increased by about 1.74 times and 1.84 times respectively, with significant differences in each period (P<0.05), the length and width of eggs increased rapidly, to mating period increased by nearly 2 times (P<0.05). At the same time, several large vesicles appeared inside the egg in mating period and disappeared in post-mating period, them should be trophoblasts, providing nutrition for oocytes. Compared with the pre-mating period, the testes of the male increased to the maximum in the mating period and shrank to the minimum in the post-mating period. There were significant differences in the three periods (P<0.05), while the length and width of the seminal vesicle both significantly increased to about twice (P<0.05) in mating and post-mating periods. This study has practical significance to precisely judge and determine the appropriate period of prevention and control, to clone reproductive-related genes, to develop new gene targeting agents, and to formulate efficient prevention and control measures of P. sauteri.

In the agroforestry system, the spatial distribution of the root system of each component determines its competitive ability to the resources in the system, which is an important basis for the design of an agroforestry system. In this paper, the root density and spatial distribution of Areca catechu and elephant grass in the compound system were studied by the zonal layered mining method, and the underground competition index of A. catechu and elephant grass was calculated by the niche overlap formula proposed by Levins. The biomass density of betel nut root (1343.88 g/m³) was 2.41 times that of elephant grass (558.53 g/m³). In the horizontal direction, the biomass density, root length density and competition index of fine roots (0-2 mm), middle roots (2-5 mm) and thick roots (> 5mm) of A. catechu decreased with the increase of the distance between roots and the base of A. catechu trunk. The root biomass density, root length density and competition index of elephant grass increased with the increase of distance, and the distribution was relatively uniform. In the horizontal direction, the root biomass density of A. catechu in 80cm from the trunk of A. catechu was significantly higher than that of elephant grass, and the root biomass density of elephant grass in 120-140 cm was significantly higher than that of A. catechu, but there was no significant difference between them in other distances. The root length density of A. catechu in 20-40 cm was higher than that of elephant grass, but the difference is not significant. The root length density of elephant grass in other horizontal distances was significantly higher than that of A. catechu. Except 20-60 cm from the trunk, the competition index of elephant grass in other areas was higher than that of betel nut. In the vertical direction, the biomass density, root length density and competition index of fine root, middle root, thick root and elephant grass root in 0-20 cm soil layer were significantly higher than those in 20-40 cm soil layer. In the two soil layers, the root length density of A. catechu root system was smaller than that of elephant grass, while the biomass density and competition index of A. catechu root system were larger than that of elephant grass. The results show that although the root distribution of A. catechu and elephant grass overlaps in space, they have their own advantages in a certain area, and neither can form an absolute competitive advantage over the other, thus both can grow healthily in the competition. Therefore, in order to effectively reduce the competition between betel nut and elephant grass, give full play to their respective advantages, and maximize their yield and benefit, we should appropriately increase the planting distance between elephant grass and betel nut trees, and appropriately strengthen the water and fertilizer input in the upper soil in the intercropping area.

In order to explore the effects of different rainfall and stand types in the same area on vegetation diversity, three regions with large annual rainfall differences in Hainan were selected to conduct vegetation diversity control experiments with different stand types. The results showed that 61 species, 58 genera, 45 families were present in the natural forests, 39 species, 37 genera, 26 families were present in the Eucalyptus plantations, and the vegetation diversity of Mangifera indica plantations, Acacia mangium plantations and Hevea brasiliensis plantations was relatively low due to frequent artificial management. The effects of rainfall on species diversity index of natural forest were significant (P<0.05), but no significant difference was found in Eucalyptus plantation (P>0.05). The species richness index (R) of natural forest and Eucalyptus plantation increased gradually with the increase of rainfall. The Shannon-Wiener diversity index (H), Simpson diversity index (D) and Pielou evenness index (J_sw) of tree layer and shrub layer of natural forest decreased with the increase of rainfall, while the herbaceous layer did the opposite. Shannon-Wiener diversity index, Simpson diversity index and Pielou evenness index of shrub layer and herb layer of Eucalyptus plantation increased with the increase of rainfall. The fluctuation of species diversity index was mainly in shrub layer and herb layer of natural forest and Eucalyptus plantation, and the change of tree layer was relatively stable. The rainfall and canopy shaded effect were the important reason for the differences in regional species diversity, compared with natural forest of Eucalyptus plantation tree layer the lack of ecological niche of the vegetation diversity was the main reason for the low and had nothing to do with the tree itself, specific provisions of other economic forest caused by frequent grass fertilizer management was relatively single species diversity. Therefore, the key to improve species diversity of the plantation is to establish a mixed or different-age forest to transform the existing pure forest to promote the release of the niche of the tree layer and change the management mode of other economic stands at the same time.