Abundant germplasm resources are the basis for mango variety breeding and industrial development. For better protection and utilization of mango germplasm resources, the TP-M13-SSR marker developed by our team previously were used to analyze the genetic diversity and construct molecular ID of 145 mango germplasms containing local cultivars, bred varieties and wild relative species, which stored in the nursery of Guangxi Innovation Base of mango germplasm resources conservation. The results showed that the average number of observed alleles for the 12 primer pairs was 3.2838, the average observed heterozygosity (H_o) was 0.5858, the average expected heterozygosity (H_e) was 0.6725, the average Shannon index (I) was 1.3383, and the average Nei's gene diversity index (N_a) was 0.6702. The polymorphism information content (PIC) of the 12 primer pairs ranged from 0.5036 to 0.7827, with an average value of 0.6396. All the primers were highly polymorphic sites. The result suggested that TP-M13-SSR primer could provide data support for genetic diversity analysis of mango. The genetic similarity coefficient of 145 materrials varied from 0.5676 to 1.000, with an average of 0.7417. The genetic similarity coefficient between Irwin and Indian No. 1 was 1.000. The minimum genetic similarity coefficient was 0.5676, between M. persiciformis 20-2 and Dadouxiang mango, M. persiciformis 20-2 and Shuoshuai mango, Jinhuang mango and Guire 10-1 mango. All the 145 mango germplasms were divided into two groups when the genetic similarity coefficient was 0.7060. Group I contained 108 mango species and 20 M. persiciformis species, accounting for 88.90% of the total number of germplasms. Group Ⅱ contained 17 specimens, all of which were M. persiciformis species. Group I could be further divided into five subgroups when the genetic similarity coefficient was 0.7330, among which subgroups I-1 and I-3 were the most abundant, accounting for 91.92% of all mango germplasms. The results of UPGMA clustering analysis showed that M. persiciformis were not clustered strictly according to the species relationship, and the overall clustering result of mango germplasms was basically consistent with its geographical origin. All the 145 materials were amplified by 12 pairs of SSR fluorescent primers to obtain the fingerprint map, and the molecular ID was obtained by the assignment of numbers and letters combination. Each pair of primers could distinguish 12.4 germplasms on average, and the identification rate was significantly higher than that of previous studies, indicating that TP-M13-SSR had more advantageous than denaturing polyacrylamide gel electrophoresis in mango germplasm identification. This study would provide scientific basis for the collection and utilization of germplasm resources and variety breeding of mango. It is also proposed for molecular identification of bred varieties, which is of great significance to the development of mango industry for providing methods for molecular identification and intellectual property of bred varieties.

In order to deepen the understanding of the tolerance of Excoecaria cochinchinensis, Nerium oleander and Fagraea ceilanica to intermittent flooding and high concentration of ammonia nitrogen, an intermittent flooding cultivation experiment was conducted with six aqueous solutions of ammonia nitrogen concentration (0, 0.5, 7.5, 14.5, 21.5, 28.5 mg/L). After 90 days of continuous test, the morphological and physiological indexes of the three plants were determined, aimed to provide theoretical references for the application of the three plants in rain garden, subsurface flow wetland, intermittent flooded green space and other environments. The results showed that: (1) Compared with the soil culture control, under intermittent flooding, all three plants showed adaptive changes in enhancing oxygen delivery to the roots, such as enlarged stem base lenticels and adventitious root formation, and significantly promoted the height growth of N. oleander. However, the growth rate of E. cochinchinensis and F. ceilanica was slowed down due to the influence of flooding; (2) Under the interaction of intermittent flooding and ammonia nitrogen, the plant height of N. oleander increased with the increase of ammonia nitrogen concentration, while the plant height growth of E. cochinchinensis and F. ceilanica was significantly inhibited after the ammonia nitrogen reaching 14.5 mg/L, and when the ammonia nitrogen was 21.5 mg/L, the leaves of E. cochinchinensis appeared symptoms such as reduced leaf area and green loss; (3) Intermittent flooding had no significant effect on the activities of antioxidant enzymes and the contents of chlorophyll, malondialdehyde (MDA), free proline (Pro) and soluble protein (SP) of the three plants. On the 60th days, the activities of antioxidant enzymes, free proline and soluble protein of the three plants fluctuated to some extent, but on the 90th day, each index had little difference compared with soil culture; (4) Under the interaction of intermittent flooding and ammonia nitrogen, on the 90th day, N. oleander could recover to the normal level even when the ammonia nitrogen was 28.5 mg/L. After the ammonia nitrogen was 14.5 mg/L, E. cochinchinensis and F. ceilanica tended to produce more antioxidant enzymes, MDA and free proline, less soluble protein, with obvious physiological disorders. It could be seen that N. oleander showed active morphological adaptation and strong resistance in the aqueous solution with ammonia nitrogen concentration of 0-28.5 mg/L, and could grow in a certain length of time and intermittent flooding environment. Although E. cochinchinensis and F. ceilanica also showed strong adaptability, the tolerance to ammonia nitrogen was weaker than that of N. oleander, and they only grew well in the range of 0-14.5 mg/L ammonia nitrogen concentration aqueous solution. Therefore, the three plants could be used in the intermittent flooded green space, and N. oleander has strong adaptability to high concentration ammonia nitrogen water environment.

The flavonoid quercetin is one of the main active ingredients in Chinese medicinal herb, Euphorbia maculata. At present, there are few reports on quercetin biosynthesis gene, and real-time quantitative PCR (RT-qPCR) is one of the common methods in gene research. But it is a prerequisite for relative quantitative RT-qPCR to have suitable reference genes. In order to obtain a suitable reference gene, this experiment was based on the results of transcriptome sequencing, EmSE, EmUBC, EmGDI1, EmLSM12, EmGBP, EmSYP22, EmTRI1, EmRSZ21, EmRPL7 and EmUBQ obtained by our research group in the early stage were selected as candidate reference genes. RT-qPCR was used to detect the expression of the candidate reference genes in roots, stems, leaves and fruits of E. maculata during vegetative and reproduction stages. The expression stability of the candidate genes was analyzed using geNorm, NormFinder and BestKeeper software. The results of different software were integrated and ranked by the geometric mean method. The ranking was in the order EmGDI1>EmUBQ>EmSE>EmUBC>EmLSM12=EmGBP>EmTRI1>EmSYP22>EmRSZ21=EmRPL7. EmC4H, a key enzyme gene in quercetin biosynthesis, was analyzed using EmGDI1 as the reference gene. The difference of EmC4H expression in different tissues at different stages was consistent with the trend of transcriptome sequencing. The reference gene EmGDI1 developed in this study could be used as a suitable reference gene for tissue-specific expression studies of different stages of E. maculata.

The present study revealed the effects of chemical fertilizer reduction patterns on growth, cane yield and fertilizer utilization rate of sugarcane, in order to provide a theoretical basis for the application of mulched drip fertigation and find out the best pattern to reduce fertilizer in sugarcane. Seven different treatments were conducted: no fertilization (CK₀), conventional fertilization (CK₁), mulched drip irrigation + conventional fertilization (CK₂), mulched drip fertigation T₁₀₀ (fertilizer amount equated with CK₁) and T₈₀, T₇₀, T₆₀ (20%, 30% and 40% reduction of fertilizer amount of T₁₀₀). Main agronomic characters, cane yield, sucrose content, sugar yield, economic benefit and nutrient utilization rate of sugarcane were measured in the seven different treatments. The results showed that compared with CK₁, the millable stalk number in CK₂ increased significantly, the tillering rate, plant height, millable stalk number and stalk formation rate in T₁₀₀ were all improved significantly, the effective stalk number and stalk formation rate in T₈₀ and T₇₀ were improved significantly. Compared with CK₁, the cane yield in CK₂, T₁₀₀, T₈₀ and T₇₀ increased significantly by 13.64%, 32.20%, 27.00% and 20.18%, respectively. In the different drip fertigation treatments, there was no significant differences for cane yield between T₁₀₀ and T₈₀, but the cane yield for T₇₀ and T₆₀ decreased significantly in contrast to T₁₀₀. There was no significant difference in sugar content among the different drip fertigation treatments. The change trend of sugar yield and cane yield among the treatments was consistent. Sugar yield in T₁₀₀ and T₈₀ was higher than that in other treatments, and there was no significant difference between that in T₁₀₀ and T₈₀. Compared with CK₁, the net benefit in T₁₀₀ and T₈₀ increased significantly by 4534.4 yuan/hm² and 3953.8 yuan/hm², respectively. The net benefit in T₇₀ and T₆₀ decreased significantly compared with T₁₀₀, and the net benefit in T₆₀ was even 2350 yuan/hm² lower than that in CK₁. The fertilizer utilization rate of all drip fertigation treatments was significantly higher than that of CK₁, and the average utilization rates of nitrogen, phosphorus and potassium fertilizers in T₈₀ were the highest in all the treatments, reached 48.36%, 27.70% and 68.95%, respectively, which was 28.42, 17.95 and 30.71 percentage points higher than that of CK₁, respectively. Overall, in the middle fertility of laterite soil, the application of mulched drip fertigation pattern for T₈₀ could obtain ideal cane yield and benefit.

To lay a foundation for the scientific evaluation of the ornamental traits of Primulina, 40 species of the Primulina were used as the experimental materials. The analytical hierarchy process was applied and four first-level indicators including foliage traits, flower traits, plant characteristics and cultivation performance to construct the constraint hierarchy were selected, then 14 secondary indexes including leaf shape, leaf pattern, leaf color, flower color and pattern, corolla size, flower quantity, flowering period, leaf arrangement, plant type compactness, peduncle shape, cultivation difficulty, pest and disease were selected to construct a comprehensive evaluation system for the ornamental traits of Primulina. The results showed that among the four first-level indexes, the weight of cultivation performance was 34.0%, which is the highest, followed by plant characteristics (26.6%), flower traits (24.0%), and foliag traits (15.4%). Among the 14 second-level indexes, the weight of cultivation difficulty, peduncle shape, leaf pattern and leaf arrangement on the ornamental value of Primulina all exceeded 10.0%. The weight of cultivation difficulty was 17.2%, which is a key indicator affecting the ornamental value of Primulina. According to the established scoring criteria, 40 species of Primulina were assigned, combined with the weight to calculate the scores, and divided into three grades: Grade Ⅰ (score over 3.5), 10 species with high ornamental value; Grade Ⅱ (score 3.0-3.5), 20 species with medium ornamental value; Grade Ⅲ (score below 3.0), 10 species with low ornamental value. Among them, the species rated as high ornamental value (Grade Ⅰ) are: P. Cleopatra, P. Snow Angel, P. guizhongensis, P. Stardust, P. qintangensis, P. Blue Mood, P. liujiangensis, P. hochiensis var. rosulata, P. Flying Wings and P. macrorhiza, these 10 species of Primulina are easy to cultivate and have outstanding performance in flower viewing, foliage and plant types, which can be used as excellent hybrid parents to participate in breeding, and can also be directly promoted to the market; the species classified as low ornamental value (Grade Ⅲ) are often difficult to cultivate, with poor stress resistance, and peduncle shape are poor, lack of characteristic flower color and pattern. The 40 species of Primulina are divided into 5 categories according to their ornamental values by cluster analysis, and the species with complementary traits can be selected as parents to produce better hybrid varieties.

Rubber tree is the most important cultivated rubber-producing plant, and the tapping of trunk is the only way to obtain natural rubber from the laticifer in the bark currently. The characteristics of latex flow after tapping determine the latex yield, but the mechanism of latex flow is not yet completely clear. The turgor pressure of bark is the main initial driving force for latex flow, and the content of lignin, as the main component of cell wall, is closely related to the turgor pressure. At present, the study on the lignin content in bark of rubber tree is deficiency, among which the analysis of lignin content by morphological structure is lack. Using the bark of RY8-79 and PR107 mature tree as the research materials, paraffin sections were prepared, and the lignin in the bark was stained and localized by Wiesner reaction, Mäule reaction, and safranin staining combined with fluorescence, respectively. The results showed that both Wiesner reaction and Mäule reaction could stain the lignin component of the parenchyma cell wall, but difficult to distinguish different strains and tissues for the light color. The light purplish red of lignin in the parenchyma cell could be observed after safranin staining, but it was also difficult to distinguish different tissues and strains. The obvious red fluorescence of lignin tissue could be observed after safranin staining combined with 546 nm green light excitation, and there was significant difference among different cell types and strains. The lignin fluorescence of parenchyma cell in RY8-79 was significantly weaker than that in PR107, indicating that the content of lignin in RY8-79 was lower than that in PR107. Iodine-bromine staining showed that the distribution of secondary laticifer was consistent with the distribution of lignin with strong fluorescence, indicating that the lignin content of secondary laticifer and its surrounding parenchyma cells increased significantly, especially in PR107. In addition, Wiesner and Mäule reaction needed dangerous chemical reagents such as phloroglucinol, hydrochloric acid and potassium permanganate (KMnO₄), respectively, and the reaction time was not easy to control for slices falling off from slides and cell wall damage. By comparison, the reagents used for safranin staining combined with fluorescence observation were safe and non-toxic, and the structure of cell in bark could maintain intact easily. According to the comprehensive analysis of different methods, for the excellent clarity of lignin as well as safety and simplicity of operation, safranin staining combined with fluorescence observation is the most suitable method for lignin location in parenchyma cell of rubber tree bark.

To explore the effect of the extract from Camellia oleifera cake on the postharvest disease resistance of pitaya, pitaya Zihonglong was sprayed with different concentrations of C. oleifera cake extract before harvest. The fruits were stored at (10±0.5)℃ and 90%-95% RH after harvest. The changes of physical and chemical properties, nutritional components, reactive oxygen species (ROS) metabolism and defense-related enzyme activities of pitaya fruits after harvest were analyzed, and the correlation between each index and comprehensively scores were analyzed. The results indicated that the preharvest spraying extract from C. oleifera cake could effectively reduce the decay index (DI) of pitaya fruit. The respiratory rate (RR) and ethylene release rate (ERR) of pitaya fruit were effectively inhibited by C. oleifera cake extract at the later storage period. Pitaya fruit treated with C. oleifera cake extract effectively delayed the decrease of ascorbic acid (AsA) content, and increased the activities of catalase (CAT), superoxide dismutase (SOD) and other antioxidant enzymes, effectively promoted the metabolism of hydrogen peroxide (H₂O₂) in fruit, reduced the H₂O₂ content, and effectively removed the ROS accumulation during the fruit physiological metabolism. Meanwhile, the C. oleifera cake extract effectively increased the activities of defense-related enzymes such as phenylalanine ammonialyase (PAL), peroxidase (POD), polyphenol oxidase (PPO), β-1,3-glucanase (GLU) and chitinase (CHI) in pitaya fruit, thus improving its disease resistance. Correlation analysis founded that pitaya fruit DI was closely related to the ROS accumulation and membrane lipid peroxidation. Decreasing oxidative stress and maintaining the integrity of cell membrane were the basis for improving the disease resistance of pitaya fruit, and enhancing the disease resistance of pitaya fruit was helpful to reduce decay. Comprehensive evaluation showed that the comprehensive score of pitaya fruit preharvest spraying with 1.00% C. oleifera cake extract was the highest, indicating that its treatment effect was the best. In conclusion, preharvest spraying with 1.00% C. oleifera cake extract could maintain quality of pitaya fruit by improving the antioxidant and disease resistance. The results provide a theoretical reference for the application of C. oleifera cake extract in the postharvest storage and preservation of pitaya.

Information management of germplasm resources is the only way to improve the efficiency of germplasm resource management, sharing is an important means to activate the utilization value of preserved germplasm resources and realize the multiplier effect of seed industry, benefit distribution in sharing activities is the original incentive to promote germplasm resource sharing, and benefit ownership certificate is the key basis for benefit distribution. At present, the management of tropical crop germplasm resources is faced with the following problems: decentralized management of resource flow business chain; distortion of information data of resources and business chain; lack of evidence chain of credible benefit distribution of resources. To solve these problems, based on block chain technology, we put forward a kind of block chain system for tropical crop germplasm resources management to solve the problem of information asymmetry, by using decentralization, tamper-resistant, marks keeping in whole process, traceability, collective maintenance, and transparency, so as to realize the many relevant institutions of tropical crop germplasm resources and link collaboration trust and consistent action, effectively address the above issues and challenges. The system can keep marks processed and trace back to source, in full life cycle of tropical germplasm resources, laid the foundation for the combination of agriculture and computer agriculture, and resource traceability issues research. It is of great significance to the efficient management of tropical crop germplasm resources and the mining of potential value.

The purpose of the paper is to investigate the physiological and biochemical mechanism of drought and low temperature stress in Sophora davidii seedlings. S. davidii seedlings were used as the experimental materials to evaluate the changes of anti-oxidant protective enzyme activities, membrane injury indexes, osmotic adjustment substances in leaves under increasingly severe drought in natural conditions, and late artificial low temperature treated, with pot experiments. The results showed that the relative water content of leaves decreased significantly with the increase of drought time, and the growth could be restored 2 days after rehydration. Moderate drought was beneficial to the accumulation of photosynthetic pigments, but the content of synchromes decreased in severe drought. Superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) activities first increased and then decreased with prolonged drought stress. The peak activity of SOD and POD was 458.85 U/g and 5.30 U/g, respectively on the 8th day, which was 142.53% and 68.25% more than CK respectively. Malondialdehyde (MDA) showed a slow increase with the prolonged drought stress, the peak value was 6.20 mmol/g FW on the 15th day, which was 108.75% higher than that of CK. Osmotic adjustment substances such as proline increased first and then decreased with prolonged drought stress, the peak value was 459.67 mg/g on the 10th day, which was 226.45% higher than that that of CK. Under drought stress and low temperature, photosynthetic pigment content of S. davidii leaves decreased significantly, and the changes of three protective enzymes activities (SOD, POD and CAT) increased first and then decreased, which were similar to those under drought stress. Malondialdehyde (MDA) and proline (Pro) showed increase gradually when cold stress continued. Three protective enzymes could play inter-coordinating roles at different stress stages for drought resistance and cold tolerance of S. davidii. The study revealed that S. davidii positively responded to stress through improved antioxidant enzyme activity and the accumulation of osmotic adjustment substances as proline, which could help to reduce reactive oxygen to the membrane damage. Drought stress could improve the adaptability to low temperature, which may be related to the enhancement of protective enzyme system and osmotic regulation ability.

In order to provide theoretical and practical basis for the effective molybdenum deficiency control measures and rational application of molybdenum fertilizer, field investigation, morphological diagnosis, leaf nutrients content determination and spraying test of ammonium molybdate were carried out in navel orange (Citrus sinensis Osbeck). Further, navel orange leaves with different degrees of chlorisis were collected to measure photosynthetic pigment concentration, photosynthesis rate, chlorophyll fluorescence parameters and photosynthetic product concentration. For normal, slight chlorisis and severe chlorisis leaves, the concentration of nitrogen, potassium, magnesium and born were all in optimum range, zinc and calcium content were no significant difference. The molybdenum content of slight chlorisis and severe chlorisis leaves were lower than that of the threshold value of molybdenum deficiency (0.10 mg/kg), and decreased significantly than the normal leaves. Spraying 0.05% ammonium molybdate significantly reduced the symptoms of chlorisis, indicating that the yellowing leaves of navel oranges in the test orchard was caused by molybdenum deficiency. Molybdenum deficiency symptoms of navel orange were with nearly round and bright yellow waterlogged spots or patches on the new leaves, and the leaves were distorted with the edge leaf rolled up or inward. Photosynthetic pigment concentration, activity of RUBP carboxylase, potential activity (F_v/F_o), maximum photochemical efficiency (F_v/F_m), electron transfer efficiency (ETo/RC) and quantum yield (ETo/CSm) of PSⅡ reaction center decreased significantly with molybdenum deficiency, while the heat dissipation coefficient (DIo/RC) increased significantly. Molybdenum deficiency significantly decreased the photosynthetic rate (P_n), soluble sugar and sucrose contents, indicating molybdenum deficiency will decrease the photosynthesis of navel orange.