To identify magnesium transporter (MGT) gene in tobacco genome and explore the mechanism of magnesium ion transport by MGT in tobacco plant, seven NtMGTs with conservative Gly-Met-Asn tripeptide motifs were identified from tobacco genome by homologous sequence alignment using the magnesium transporter family genes in rice and Arabidopsis genomes as reference sequences. The results showed that the expression of NtMGTs was tissue-specific and light-induced under different magnesium supply levels and light intensities. The expression of NtMGT1 in roots and NtMGT2, NtMGT4 and NtMGT5 in leaves of tobacco plants increased under strong light intensity. With the increase of magnesium supply, the expression of NtMGT1 gene in the root system increased, which was consistent with the change trend of magnesium content in the root system, suggesting that NtMGT1 gene mainly mediated the absorption of magnesium in the root system of tobacco plant. The expression levels of NtMGT2, NtMGT4 and NtMGT5 genes in leaves increased first and then decreased, indicating that the three genes belonged to a high affinity magnesium ion transport system. These results implied that under the stress of high temperature and strong light intensity, appropriate magnesium supply could increase the expression of NtMGT1 in the root part of tobacco plants, promote the absorption of magnesium ion by the root system, enhance the gene expression of NtMGT2, NtMGT4 and NtMGT5 in shoot part of tobacco plants, promote the transport of magnesium ion, and ensure the normal growth and development of tobacco plants. The results of this study can provide theoretical guidance for reasonable application of magnesium in tobacco production.

Tobacco growth information is an important basis for tobacco production management. Through a comprehensive understanding of the application of remote sensing technology in tobacco growth monitoring and yield estimation, the study aims to provide a scientific reference for the use of remote sensing technology in refined tobacco field management. Based on reviewing relevant literatures, the application of remote sensing technology in tobacco growth monitoring and yield estimation was systematically summarized from three scales of ground spectrum, UAV(unmanned aerial vehicle) remote sensing, and satellite remote sensing, and the prospect of further research was also discussed. (1)Based on the ground spectrum, the physiological and biochemical parameters (nitrogen, phosphorus, potassium, biomass, leaf area index, chlorophyll, etc.) of tobacco were estimated by reflectance spectrum and its different transformation forms, spectral index and spectral position variables, providing a basis for the diagnosis of tobacco growth, health status and maturity. Tobacco growth monitoring, yield estimation and quality evaluation could be realized. (2) UAV remote sensing technology could be used to extract tobacco areas on a small scale, monitor and estimate yield, but it could not monitor the subtle changes of tobacco due to the influence of the resolution, terrain and self stability of the camera. (3) With optical remote sensing data such as LandSat, SPOT, MODIS HJ-1, etc., as well as SAR data, by remote sensing image fusion, classification and other technologies, large-area tobacco field disease, growth monitoring and yield estimation could be achieved. The future research will focus on quantitatively studying the tobacco parameters by combining with multi-source and multi-platform remote sensing data, and conducting the dynamic monitoring of tobacco growth process on large scale by assimilation technology, thus to explore the optimal harvest time of tobacco.

Tobacco black shank, caused by Phytophthora parasitica var. nicotianae, is an important destructive disease of tobacco, which seriously threatens the sustainable development of tobacco industry. In recent years, great progress on biological control of tobacco black shank has been made. To provide reference basis for biological control of tobacco black shank in the future, the authors reviewed the advances in the studies of biological control microorganisms (bacterium, fungi, actinomycetes) as well as botanical fungicides against the Phytophthora parasitica var. nicotianae, and introduced the biological control mechanisms. In addition, the authors also analyzed new problems in biological control of tobacco black shank under global warming and made an outlook on future research.

Although overall level is not high, tobacco seedling has basically realized intensive and standardization in China. The cost of seedling is expensive, the links of technology are complex, cutting leaves and disinfection need much time and labor, has limited the sustainable development of production of tobacco further. The existing intensive seedling ideas and technology system has been difficult to adapt to the new situation of development. For reducing the cost of seedling improving the quality of seedling, the paper has stated the concept of intensive simplified and labor saving seedling of tobacco, summarized the advantage and disadvantage of the tobacco seedling in current situation, formed simplified and labor saving seedling technology including the way of simplified and labor saving seedling, ecological seedling substance, mechanical and digital technology, and looked intensive simplified and labor saving seedling of tobacco into future.

In order to provide the scientific basics for quality assessment of organic fertilizer commonly used In tobacco as well as rational use of organic fertilizers, this article analyzed the main components of organic fertilizer commonly used in tobacco, classify as well as evaluate the quality of the organic fertilizer, the main components of these organic fertilize were carbon, nitrogen and phosphorus factor. Five types of the organic fertilizer was divided into four quality levels: the first level was cake that contains of high phosphorus, nitrogen, organic matter and nutrients; the second level was ryegrass and sweet potato vine that contains of medium nitrogen, high organic matter and organic nutrients; the third level was pig manure and chicken manure, the feature of this level was high content of nitrogen and phosphorus but low organic nutrients; the last level was cow dung, wheat straw, corn stalks and so on, the feature of this level was poor content of nitrogen, phosphorus, organic matter and organic nutrients. We should take rational application of various types of organic fertilizer based on the actual soil conditions.

In order to find an effective way to extract RNA in tobacco leaves and provide theoretical basis for tobacco molecular biology research, tobacco leaves were used as material, 3 methods including RNA isolation kit, Trizol method and RNAiso method were used to extract RNA, then RNA were detected by gel electrophoresis and spectrometer. The results indicated that the operation of RNA isolation kit was very easy, but the extraction was the least; Trizol method was convenient and efficient, but there were proteins and a little degradation in RNA; in contrast, the concentration of RNA extracted by RNAiso method was very high and ranged from 100 to 500 ng/μL, A₂₆₀/A₂₈₀ was from 1.8 to 2.0, RNA bands were clear and bright without degradation, and the brightness of 28S band was about twice that of 18S band; RT-PCR result showed that 2500 bp target gene consistent with the reference sequence was obtained, and it could be used in functional verification. Hence, RNAiso method was the best way to extract total RNA in tobacco leaves and had been used in many laboratories.

For the method of rapid diagnosis of Ralstonia solanacearum contain in tobacco fields, this paper based on the comparison result of the five whole-genome of the published genomes of Ralstonia solanacearum, designed nine pairs of specific primers of Ralstonia solanacearum, and has achieved three pairs of primers for specific amplification of Pseudomonas solanacearum by screening and verification. The application of the screened primers could be used as an effective method to do specific detection of tobacco Ralstonia solanacearum in the soil. As a preliminary conclusion, the lowest detection rate of Ralstonia solanacearum in the soil was 2×106/g. Thus, it’s a rapid and accurate new way for detection of tobacco Ralstonia solanacearum in the soil.

To screen effective drugs for controlling tobacco Bemisia tabaci, toxicity test and field efficacy of 3 biological insecticides to B.tabaci were used on tobacco. The toxicity test results showed that the virulence of B.tabaci presented as 0.5% ivermectin EC > 0.5% veratridine Solution > 6% rotenone microemulsion, and the LC50 values of them were 1.396 mg/L, 5.083 mg/L, 12.287 mg/L respectively, which was significantly better than the CK cyhalothrin (LC50 = 30.67 mg/L). Results of field efficacy showed that the adjusted efficiency of 3,7,14 days after treatment of 2000 times of dilution of 6% rotenone microemulsion, 0.5% ivermectin EC, 0.5% veratridine solution were over 70%. Therefore, the 3biological insecticides have no harmful effects on the tobacco field, and the tobacco plants are safe to grow and can be further promoted and applied in production.

The aim was to investigate the effect of salt stress on the seed germination and physiological characteristics of tobacco. The relative germination potential, relative germination rate, root length, chlorophy ll content, cell membrane permeability, MDA content and proline content were measured. With the increase of NaCl concentration, the relative germination potential, relative germination rate, root length, chlorophy ll content kept decreasing; Cell membrane permeability and proline content kept increasing; the malondiadehyde content increased at first, and then decreased with the increase of NaCl concentration. When the concentration of NaCl was up to 1.2% , the tobacco leaf chlorophy ll content declined to the maximum extent and the malondiadehyde content reached maximum value which provided a reliable basis for the study of tobacco salt tolerance mechanism.

To find new resistance genes and study perilipin gene 8-3 related to Sclerotinia sclerotiorum, a couple of primers containing restriction enzyme sites of Xba I and BamH I were designed to clone the 8-3 from cloning vector pMD19-T-8-3, and the product was digested and lignased with plant expression vector pBI121. The pBI121-8-3 was transformed into LBA4404 and the 8-3 gene was transformed into Nicotiana tabacum 89 mediated by Agrobacterium tumefaciens. 35 resistant lines were obtained, 21 of which were identified as transgenic plants by PCR and sequencing. The further identification of RT-PCR was confirmed that the 8-3 was expressed in the transgenic plants. The transgenic tobacco infected with Sclerotinia sclerotiorum and oxalic acid showed that 8-3 could improve the plants' tolerance level to oxalic acid and enhance the resistance to Sclerotinia sclerotiorum to a certain extent, which laid the foundation for the study of 8-3 gene and plant resistance to Sclerotinia sclerotiorum.

This paper expounds the physiological function and the mechanism of absorption and distribution of chlorine. Recent researches on the relationship between chlorine and tobacco quality, the main factors influencing chlorine content and the genetic analysis of chlorine in tobacco were also reviewed. The distribution of chlorine content in domestic tobaccos exists imbalanced phenomenon, mainly manifested as south-low and north- high. The problem of high chlorine in the northern area, especially Huanghuai Tobacco Region remains the influence factor limiting tobacco industrial availability. This article presents that precision agriculture in the direction of the development of tobacco chlorine nutrition, and points out the research of chlorine nutrition in tobacco molecular genetic level were still few studies. Correlation analysis technology was an important means of macro and micro combination on the modern research of chlorine nutrition in tobacco. These conclusions and prospects were to provide reference for the cultivation of tobacco science and the improvement of the quality of tobacco leaf.

Sodium percarbonate, a new disinfectant, has been widely used in the sterilization and cleaning of objects, but has not been reported in the surface sterilization of plant seeds and explants. In this study, tobacco seeds were used to study the effects of three sterilizing agents, including sodium percarbonate, sodium hypochlorite and mercuric chloride, on the seed surface sterility and their effects on seed germination and plant growth. Tobacco seeds were treated with 4.0% aqueous solution of sodium percarbonate (active oxygen content ≥0.54%) for 20-40 min and then inoculated directly onto MS medium for germination and growth. While the other two groups were sterilized separately with 33.3% sodium hypochlorite solution (active chlorine content ≥1.65%) for 10 min and 0.1% aqueous solution of mercury for 4 min, then cleaned for 5 times with sterile water and inoculated on the same medium. The results showed that 90% of seeds germinated and no plantlet was contaminated, indicating that the three methods were effectively. The seeds germinated fast and the plantlets grew well by sodium percarbonate and sodium hypochlorite treatments, and the group of sodium percarbonate treatment was slightly better than that of sodium hypochlorite. However, mercury delayed seed germination and inhibited plant growth. In addition, sodium percarbonate eliminates the need for cleaning after sterilization, exhibiting a great advantage. This study established a new method for tobacco seed surface sterilization, which provides a reference for the sterilization of other plants seeds and explants, showing very practical value.

To explore the mechanism of tobacco male sterility and search for the key causes, this paper concludes the present research status of male sterility in tobacco based on phenotype, cytology, physiology & biochemistry, molecular mechanism and so on. Firstly, we summarized that the distinguish characteristics of tobacco sterile lines and their maintainer lines in tapetum and flower organs. Secondly, we analyzed that the effects of free proline, active oxygen, enzyme and endogenous hormones on the tobacco fertility. Finally, we described in detail that the research and analysis of the association of nuclear genes, mitochondrial genes and chloroplast genes with tobacco fertility. Furthermore, it is presented that the follow-up studies combined with the high-throughput data effectively will be benefit for the systematical research of male sterility on tobacco.

Some plants could accumulate glycine betaine by self synthesis so as to alleviate the injury caused by drought, low temperature and salt stress. Meanwhile it could promote the accumulation amount of glycine betaine by genetic engineering or exogenous application for plants which could not make by themselves. This article summarized main research progress on discovery, biosynthetic pathway and applications of glycine betaine in plants, meanwhile evaluated research status, existing problems and application prospect of glycine betaine in tobacco. At last, we concluded that glycine betaine had the popularization and application potential in paddy yield of tobacco for its low cost, little dosage and strong stress resistence.

Skimmed milk and trisodium phosphate, which have a significant passivation effect on tobacco mosaic virus (TMV), were selected as the research objects. The passivation effect of the combination of skimmed milk and trisodium phosphate (called Yiduling) on TMV-contaminated substrate and leaf-cutting device during floating seedling cultivation was determined by the dead spot method. The effects of Yiduling on viral granules were observed by transmission electron microscopy. At the same time, real-time qPCR was used to quantitatively detect the content of TMV and the relative expression of host defense protein. The results showed that the passivation effect of Yiduling diluent on TMV was time and concentration dependent, and the inhibition rate was significantly different between different treatments. Yiduling mixed with TMV inoculum for 3 minutes completely inhibited the infection of TMV on leaves. The best inhibitory effect was obtained when 500 times Yiduling was used for disinfection for more than 1 min. The passivation effect on TMV was up to 100% when the leaf-cutting device was soaked with Yiduling diluted 500 times for no less than 5 minutes. Different concentrations of Yiduling diluent significantly inactivated the TMV in the substrate and inhibited the infection and morbidity of tobacco seedlings by TMV, and the content of TMV in the substrate decreased by 74.09%-90.26% and the relative control effect reached 54.83%-85.45%. In addition, the tobacco seedling leaves in all treatments with Yiduling were normal and no phytotoxicity occurred. The study of the mechanism of inactivating virus found that the virions after co-incubation with Yiduling diluent were broken into tiny fragments, the coat protein was severely damaged, and the helical structure and columnar shape were basically lost. At the same time, Yiduling increased the enzyme activity of defense enzymes PPO and PAL, and significantly induced the expression of defense genes NPR1, PAL, PR1b and PR1a. In summary, Yiduling can have antiviral effects by directly acting on virion and inducing host resistance.

Nitrogen is the necessary nutrient for the growth and development of tobacco. It has a certain influence on the chemical process of tobacco, such as chemical synthesis, energy conversion and signal transmission. Ammonium nitrogen and nitrate nitrogen are the main nitrogen forms of tobacco absorption, which have different effects on different parts of tobacco and different parts. The reasonable ratio of nitrogen is beneficial to the uptake of nitrogen and the improvement of tobacco leaf quality. In this paper, the effects of different nitrogen forms on the growth and development, growth, element absorption, photosynthetic characteristics and carbon and nitrogen metabolism of tobacco were reviewed. The effects of different nitrogen forms on the growth and development of tobacco were studied. Influence the relevant research to provide the basis.

Abstract：The N gene, cloned from wild tobacco（Nicotiana glutinosa）, is a type member of the Toll-IL-1 receptor homology region (TIR)-nucleotide binding site (NBS)-leucinerich repeat region (LRR) class of R genes and confers resistance to tobacco mosaic virus (TMV). The N gene was isolated by insertional mutagenesis using the Activator (Ac) transposon of maize，and N-TMV interaction is one of the earliest and most studied models of plant-pathogen interaction. In this article, the research progress of N gene in structure, expression, action mechanism were reviewed from the transcription products, expression characteristics, temperature sensitivity, corresponding avirulence gene and other aspects; The efficient using and achievements of N gene in TMV resistance breeding were summarized; And the prospect of efficient using of N gene was gave from three aspects, which is the mechanism research of resistant to TMV, identification and utilization of germplasm resources.

The achievements about analysis of organic acids in tobacco at home and abroad over past years were reviewed comprehensively, and analyzed the properties and effects of various organic acids, such as volatile, semi-volatile and nonvolatile acids. Pretreatments of samples included solvent extraction, solid phase extraction, stream distillation, etc. Finally, this paper comprehensively introduced analysis of organic acids in tobacco about gas chromatography-mass spectrometry, high performance liquid chromatography (HPLC), ion chromatography (IC) and other methods. It was considered that it was possible to get a good understanding of various elements in smoke as the application and development of this modern separation technology and analysis equipment. And it provided factual basis for perfuming in tobacco industry.

In order to figure out the effects of tobacco stubble returning on rice growth and yield, pot experiments were conducted to test the dynamic change of rice tillering, plant height and roots, and the accumulation of dry matter, nitrogen, phosphorus and potassium, and the effects on rice yield by simulating different tobacco stubble returning. The results show that tobacco stubble returning could promote rice tillering, plant height and root development, the accumulation of dry matter, nitrogen, phosphorus and potassium, and rice yield. The tobacco stubble total returning and the tobacco root returning could increase the yield by 17.35% and 8.60%, respectively. Tobacco stubble total returning is beneficial to the growth and yield of rice, and it can be popularized in tobacco rice multiple cropping area.

Bio-organic fertilizer has the advantages of improving soil fertility, regulating soil micro-ecological environment, raising fertilizer utilization rate, accelerating plant growth, improving tobacco yield and quality, enhancing disease resistance and so on, and the application of bio-organic fertilizer meets the requirement of sustainable development of tobacco production. The authors introduced the development process of bio-organic fertilizer in China, elaborated the production and application status of bio-organic fertilizer, and discussed the effect and mechanism of bio-organic fertilizer application to tobacco production. At the same time, the authors put forward the future study direction of bio-organic fertilizer, thus to provide references for tobacco production and soil improvement.

To catalogue and preserve 23 tobacco germplasm resources collected from Hainan Province, agronomic characters and genetic diversity of these tobacco germplasm resources were investigated, and the fingerprints were constructed. The results showed that the agronomic traits and qualitative traits of tested germplasms varied greatly. The coefficient of variation ranged from 20.69% to 29.41% in different agronomic traits. These collected tobacco germplasms were divided into 3 groups by clustering analysis. The germplasms from the second group were the tallest with the largest leaf, which could be used for high-yield breeding. In addition, 12 pairs of primers with specific amplification were screened from 2000 pairs of SSR primers, and 46 polymorphic bands were obtained. An average of 3.83 alleles was observed for each primer pair with the average heterozygosity (Ho) of 0.5301, and the average expected heterozygosity (He) of 0.4700. Shannon’s index was 0.8930, Nei’s index was 0.4593. The genetic diversity of the 23 tobacco germplasm resources was relatively abundant. These varieties were clustered into two groups at the genetic similarly coefficient of 0.206 by UPGMA cluster analysis. At the same time, 12 pairs of primers were used to construct the fingerprints of the 23 tobacco germplasm resources, which laid a theoretical foundation for the research on the identification system of sun-cured tobacco varieties. The study can provide reference for identification and utilization of sun-cured tobacco germplasm resources and selection of parent materials for cigar breeding.

To explore the effects of different proportions of slow-release fertilizers applied with tobacco specific compound fertilizers on tobacco-growing soil fertility and flue-cured tobacco yield and quality, a field test of five fertilizer combinations and CK were set up in the tobacco growing area of Reshui Town in Xuanwei City, and the soil and flue-cured tobacco leaves were sampled and analyzed. The results showed that the integrated fertility index (IFI) of the soil increased by 12.50%-23.21% under the five proportions of slow-release fertilizer combined with the special compound fertilizer for tobacco, compared with that of CK (single application of special compound fertilizers for tobacco), and IFI of soil was the best by replacing the compound fertilizer with 60%-100% of slow-release fertilizer (T3, T4 and T5 treatment). From the perspective of comprehensive quality of flue-cured tobacco, the average score of comprehensive quality of flue-cured tobacco increased by 0.19%-6.64% compared with that of CK by using different proportions of slow-release fertilizer instead of tobacco specific compound fertilizer. Among them, T4 treatment of 80% slow-release fertilizer replacement for compound fertilizer showed the best performance. T4 treatment had the best economic benefit, and the output value reached 59995.80 yuan/hm², which was higher than that of the control and other treatments. In conclusion, the ratio of slow-release fertilizer and compound fertilizer of 80%:20% could better improve the comprehensive quality of tobacco leaves, obtain good economic benefits of flue-cured tobacco leaves and improve the soil nutrient structure to a certain extent.

In view of the single green control bactericide for tobacco angular leaf spot disease, it is urgent to screen out high-efficiency and low-toxicity bactericides for tobacco green control practice. Twelve bactericides with different nature were tested by plate counting method. Six bactericideswith good laboratory bacteriostasis effect were selected for field control evaluation.The results showed that patented bactericide for Chinese Herbal Medicine, 12% zhongshengmycin WP and 2.1% eugenol?carvacrol AS had the best laboratory bacteriostasis effect,the bacteriostasis rate was 100%; Secondly,10 billion Bacillus subtilis WP were produced and 40% zinc thiazole SC, with bacteriostasis rates of 82.84% and 76.14%;The bacteriostasis rate of 6% kasugamycin WP was 63.47%, that of other bactericides was less than 50%, and that of 72% streptomycin sulfate SPX was only 44.1%. Field trials showed that the effects of 10 billion Bacillus subtilis WP, 40% zinc thiazole SC, Chinese herbal bactericide WF, 12% zhongshengmycin WP were from high to low, respectively. The field control effects of the four bactericides ranged from 60% to 65%. these four bactericides can be recommended for green control of Tobacco Angular Leaf Spot Disease.

Root-knot nematode has become the major threat to tobacco in Panzhihua, and caused serious yield loss. To screen biological agent with high efficiency and safety, a field experiment was conducted to determine the effect of four biological agents against tobacco root-knot nematode in Ganbazi, Renhe during 2017-2018. The efficacy was evaluated comprehensively through control efficacy, the correction control efficacy of the decline rate of the second- stage juveniles and the yield- increasing efficiency. The results showed that ‘Yongwei?168’agent gained the highest comprehensive performance with the control efficacy of 62.11%, the correction control efficacy of the decline rate of the second-stage juveniles of 81.05% and the yield increase effect of 53.08% 120 days after the treatment. Therefore,‘Yongwei?168’agent has a good application prospect on controlling tobacco root-knot nematodes.

To study the mechanism of aphid resistance in tobacco varieties, six tobacco varieties with different aphid resistance were selected and inoculated with aphid in pot experiment. The content change of jasmine acid (JA) and nitric oxide (NO), and CAT activities in tobacco leaves were determined 0, 3, 6 and 9 hours after feeding aphid. The results showed that: after being infested by aphids, the JA content in tobacco leaves increased first, peaked at 6 hours and then decreased. The increment of JA content in resistant varieties was higher than that in susceptible varieties. The NO content in leaves of aphid resistant varieties increased first, peaked at 3 hours and then decreased. The difference of the NO content in leaves of susceptible varieties was not significant between 3 hours’ aphid feeding and 0 h, but decreased significantly after 6 hours and 9 hours. The CAT activity of all tested tobacco varieties showed an increasing trend at 9 h, and CAT activity of aphid resistant variety ‘Shubalaomuji2113’ increased the most. Therefore, JA and NO contents and CAT activity could be used as physiological indicators for aphid resistance identification in tobacco varieties. The increase of JA content in leaves 5-6 hours after inoculation could be used to identify the resistance of tobacco varieties to aphids.

Bemisia tabaci infection can induce the tobacco resistance to Myzus persicae. The study aims to investigate the relationship between the defense signaling of salicylic acid (SA) and jasmonic acid (JA) and the resistance to Myzus persicae induced by Bemisia tabaci. The effects of Bemisia tabaci nymphs feeding on SA and JA level and downstream defense genes expressing level were tested, and the effects of exogenous SA and JA on the growth and development of Myzus persicae were analyzed by biochemical analysis and real-time fluorescent quantitative PCR. The results showed that Myzus persicae infection obviously activated SA defense pathway. After feeding 15 d, the SA level was 1.40-fold higher than the control, and the levels of PR-1a and PR-2a were increased by 3.22 times and 0.74 times, respectively. JA level was not obviously affected, while the transcript levels of JA downstream defense genes PI-II and TPI were decreased by 73.91% and 56.73%, respectively. Biochemical analysis revealed that the application of exogenous SA was harmful to the survival and the relative average growth rate of M. persicae. Treating with 1 mmol/L SA, aphid survival and growth rate were decreased by 43.2% and 11.54%, respectively, compared with the control. Methyl jasmonate had no harmful effect on the growth and development of Myzus persicae. In conclusion, SA mediated defense response contributes to the tobacco resistance against M. persicae.

Tobacco is used as the experimental material, with the floating seedling culture, the effects of the best ratio of vermicompost (30% vermicompost+ 30% peat+ 20% perlite+ 20% vermiculite) and conventional substrate on the growth and the metabolizing enzyme activities of tobacco in seedling stage, cluster stage and vigorous growth stage were studied, so as to provide technical reference for the application of vermicompost substrate seedling. The results show that, in the seedling stage, the method of vermicompost seedling culture could significantly promote the fresh weight of leaves, total root length, root volume, root diameter, and root activity, compared with the conventional substrate seedling culture. In the cluster stage and vigorous growing stage, the root growth of tobacco with the method of vermicompost seedling culture is better than that with conventional substrate seedling culture, and the root activity could reach significant difference level, increased by 23.50% and 24.98% respectively. However, there is no significant difference in the activity of nitrogen-transformation-related enzymes between the different seedling culture in the cluster stage and the vigorous growing stage. In conclusion, vermicompost substrate could promote the growth of tobacco at seedling stage, cluster stage and vigorous growing stage, and has a more obvious impact on tobacco root growth indicators, so vermicompost substrate is suitable for tobacco seedling in the field.

The investigation of incidence and prime control?measures of tobacco root rot were made in places?such?as Jiaxian and Baofeng in Pingdingshan tobacco plant areas, in order to solve the problem that the quality and products of tobacco were seriously damaged by tobacco root rot caused by fusarium. The?economic?losses caused by tobacco root rot was also calculated. The control efficacy of EM?microbial agent by different manner such as soil application, watering application and foliar?application was studied took the main mariety Zhongyan 100 as?experimental?material. The soil application study showed that treatment at tilling stage, transplanting stage and earthing-up stage together works best. The morbidity?and?mortality were 23% and 16% respectively. The watering application study showed that treatment at tilling stage, transplanting stage, resettling?stage, fast growing stage and topping stage together works best. The morbidity?and?mortality were 18% and 11% respectively. The foliar?application study showed that there was no significant variation between different treatments and the control. Comprehensive results showed that watering application had a remarkablecontrol effect to tobacco root rot. This results provided some theoretical references for the?biological?control of tobacco root rot.

Tobacco is one of the important economic crops in China. The tobacco pest species have reached more than 300 in China, which severely restrict the production of tobacco. Plant insect resistance is the most cost-effective means to control pests. To better understand current researches on tobacco resistance to pest at home and abroad, this review summarized basic composition of tobacco resistance to pests and induced chemical defense, signal pathways and molecular mechanisms. It was suggested that the main pests on tobacco had been transformed from the Lepidoptera pests to the sucking pests. However, the researches on tobacco insect resistance and resistance breeding aimed at single pest at home and abroad. Therefore, the study on comprehensive resistance to different pests and the breeding of multi- resistant varieties should be strengthened. At the same time, it was pointed out that photosynthesis was a systematic reaction of plant defense against insects. In the process of improving the tobacco resistance to insect and tobacco resistance breeding, the primary metabolic process of tobacco, especially photosynthesis, should also be the focus. Study on tobacco resistance to insects should be carried out with multi-disciplinary combination, to elaborate the issue from a number of perspectives, especially plant physiology, molecular biology, tobacco cultivation and tobacco breeding.

Tobacco good agricultural practice (GAP) is a set of operational standards which assure tobacco leaf safety and cover entire leaf production process. The core of GAP is hazard analysis and quality control. It also emphasizes environment protection, sustainable development, employee safety and welfare. China tobacco GAP should not only pursue economic efficiency and preserve environment quality, but also take on social responsibility. The basic principles of China tobacco GAP must include assure tobacco leaf quality and safety, protect environment and resources, safeguard employee health and welfare, economically use facilities and promote rural harmonious development.

The paper aims to utilize abandoned tobacco straw and improve its utilization rate effectively, so as to make tobacco plants grow healthier. In this study, the enzyme solution made from the common abandoned tobacco straw in field was used to mix with the screened actinomycetes, Streptomyces griseochromogenes, and the effects of mixed enzyme solution on the growth and development of tobacco seedlings and tobacco plants at seedling and harvest stage were studied. The results showed that: the application of tobacco enzyme solution could increase the yield and quality of tobacco and the ratio of tobacco to superior tobacco; among them, the mixed application of tobacco enzyme solution and S. griseochromogenes had the best effect, which was superior to other treatments and significantly superior to the control. The method of mixing tobacco enzyme solution with antagonistic actinomycetes can be recommended for tobacco production, which not only reduce the accumulation of pathogens caused by abandoned straw in field, but also effectively improve the yield and quality of tobacco.

In this study, flue-cured tobacco ‘Cuibi No.1’ was used as the material, and four concentrations of magnesium supply (0, 12.0, 48.0 and 120.0 mg/L) and two light intensities [600 and 1200 µmol/(m²·s)] at 33℃ were designed to study the effects of magnesium supply on the physiology of tobacco plants under high light intensity and high temperature stress. The results showed that: (1) the contents of sucrose and soluble sugar in the shoots and roots of tobacco plants were significantly affected by the supply of magnesium and the intensity of light, while the starch content of tobacco plants was also significantly affected by the light intensity; high light intensity could induce the accumulation of soluble sugar in the shoots and roots of tobacco plants, and the soluble sugar in the shoots reached its maximum value under high light intensity when the magnesium supply was 48.0 mg/L; (2) with the increase of magnesium supply, the activities of key enzymes in carbon and nitrogen metabolism, including sucrose synthase (SS), sucrose phosphate synthase (SPS), acid invertase (AI), glutamine synthase (GS) and nitrate reductase (NR), increased first and then decreased, and reached the maximum at 48.0 mg/L of magnesium supply; these enzyme activities in tobacco plants under high light intensity were higher than those under normal light intensity; magnesium supply, light intensity and magnesium supply × light intensity significantly affect NR and AI activities in the shoots of tobacco plants; (3) high temperature and high light intensity enhanced the absorption of K⁺ and Ca²⁺ in tobacco plants, but the absorption was inhibited with the increase of magnesium supply; magnesium supply, light intensity and magnesium supply × light intensity significantly changed the contents of K⁺ and Ca²⁺ in the roots of tobacco plants. Appropriate magnesium supply (48.0 mg/L) could enhance the activities of key enzymes of carbon and nitrogen, promote the metabolism of carbon and nitrogen, increase the accumulation of soluble sugar, and then alleviate the damage of high temperature and high light intensity to tobacco plants.

This article reviewed three main kinds of therapeutic proteins produced by tobacco bioreactors, concluded the expression systems producing exogenous recombinant protein including nuclear expression, chloroplast expression and transient expression, and highlighted oral tolerance induction using tobacco expressing autoantigens, accordingly this article raised the problems to be solved in tobacco bioreactor research and the solutions. From above analysis, prospect was made for further improvement of tobacco bioreactor for production of pharmaceutical proteins and its application in China's tobacco control programs.

To understand the mechanism of boron transportation in tobacco, the boron influx transporter gene was cloned in Nicotiana tabaccum, and its expression was analyzed. The open reading frame (ORF) of boron influx transporter was predicted by biology informatics methods, and cloned by PCR technique, verified by sequencing. Its structure was also predicted by biology informatics methods. Semi-quantitative RT-PCR was used to monitor its expression levels in different tissues of tobacco with different treatments. Results showed that the complete ORF sequence of tobacco influx boron transporter, NtNIP5;1 was cloned. Its ORF contains 894 bp, encodes 297 amino acids and includes MIP protein signature sequence HLNPSLTIA. GenBank accession number is KF611892. Its protein consists of α-helix mainly in secondary structure, and was composed of five transmembrane domains. Results of RT-PCR showed that NtNIP5;1 were expressed in roots and leaves, and showed higher levels in leaves. Its expression was inhibited by 6-BA, SA and ABA.

To provide a basis for high quality tobacco production in China, we review the effects of genotype on tobacco quality, the regulation of different genes on tobacco aroma substances, and the effects of light,temperature, moisture, soil, fertilizer and cultivation methods on tobacco quality. The results showed that the quality traits of tobacco were affected by many factors, such as genetic factors, ecological factors and cultivation methods, which had different effects. It could not fundamentally solve the problem of poor quality of tobacco in China by simply improving an individual factor. Therefore, according to the effect of different impact factors, we should strengthen the efficient use of high-aroma breeding resources, breed high-quality tobacco varieties, enhance the application of modern breeding biotechnology, establish and improve the supporting system of high-quality tobacco quality production.

Pythium was isolated from tobacco stems back rot samples in Song County of Henan Province. In order to know its classification and pathogenicity to tobacco, the morphologic characters that based on microscopy technology were examined and recorded, the rDNA- ITS sequences were analyzed, the pathogenicity tests were conducted. The results showed that the colonies were actinomorphic and gradually grow into petaliform; hyphas were without separate; sporangiums were spherical or pear-shaped; archegoniums were spherical; antheridiums are bell-shaped or irregular. According to the results of the analysis of rDNAITS sequences, the sequence homology was more than 99% when it was compared with the sequence of registration number kc014615.1 and gu133597 in GenBank. Therefore, the pathogen was identified asPythium vexans de Bary. Seedings in ten leaf stage of‘Zhongyan 100’tobacco variety were inoculated withP. vexans de Bary, and the disease symptoms and the disease indexes were surveyed and recorded in the 7th day, the disease index ofPythium vexans was 48 and theP. aphanidermatum was 62.7, the results indicated that the pathogenity ofPythium vexans was less thanP. aphanidermatum.

To accurately predict the yield of tobacco in Shaoyang, soil samples from 70 tobacco growing areas were taken as the research objects. Firstly, the principal component analysis (PCA) was used to analyze the impact of 19 soil nutrient indexes on tobacco yield. The results showed that the yield of tobacco in Shaoyang was mainly affected by 9 soil nutrient indexes, including organic matter, available zinc, available boron, available manganese, available sulfur, exchangeable calcium, total potassium, available iron and available potassium. After that, support vector regression (SVR) was used to predict the tobacco yield of the 70 tobacco growing areas in Shaoyang. The results showed that the mean square error (MSE) of prediction results with 9 soil nutrient indexes was significantly less than the MSE of prediction results with 19 soil nutrient indexes. Finally, compared with that of random forest regression algorithm, the prediction accuracy of SVR was obviously better. The method based on principal component analysis and support vector regression is effective to predict tobacco yield in Shaoyang.

To screen out the biocontrol bacteria that can effectively control tobacco bacterial wilt, a strain 69-1 with obvious antagonism was isolated from the tobacco rhizosphere soil by dilution coating method, and the strain was identified as Streptomyces spectabilis and used for field control experiments of tobacco bacterial wilt. The results showed that compared with the control, the stem circumference, effective leaf number, maximum leaf width, maximum leaf length, single leaf dry weight, maximum leaf area, and yield of tobacco leaves treated with strain 69-1 increased significantly. The relative control effect on tobacco bacterial wilt reached 60.42%. At the same time, the chemical composition of the flue-cured tobacco leaves of different treatment groups was analyzed and found that the tobacco quality under strain 69-1 treatment was better than that of control. The bacterial agent treatment of the strain can not only enhance the control effect of tobacco plants against tobacco bacterial wilt, but also improve the quality and yield of tobacco leaves, and the study can provide a certain reference for the biological control of tobacco bacterial wilt.

To provide biocontrol microbial resources for the prevention and control of tobacco rhizome diseases, biocontrol strains with good control efficacy on Ralstonia solanacearum and Phytophthora parasitica were screened. The bacteria strains were isolated from the rhizosphere soil of the diseased tobacco plants, and the inhibitory activity was determined by plate face-off method and filter method. The control efficacy of highly active strains was further detected by pot tests. Molecular biological identification of the highly active strains was carried out by 16S rDNA. The promoting and antibacterial activities of the strains were verified by PCR using 9 pairs of specific primers. Two highly active strains LF-1 and LF-2 were obtained and identified as Bacillus subtilis and Bacillus amyloliquefaciens. The results of activity test showed that the inhibition rate of the two strains was 31.16% and 56.98% on R. solanacearum, and 64.44% and 72.44% on P. parasitica, respectively. The corresponding potted experiment showed that the inhibition rate of the two strains was 69.54% and 72.49% on R. solanacearum, and 65.49% and 68.32% on P. parasitica, respectively. The two strains had good control effect on tobacco rhizome diseases and broad application prospect in tobacco disease control.

To clarify the decomposition characteristics of tobacco residues returning to field and the effect on the nicotine content in soil and rice plants, pot experiments were used to study the decomposition characteristics of tobacco stems and roots, and the dynamic changes of soil pH, organic matter and nutrients and nicotine. The results showed that: (1) the decomposing rate and nutrient release of tobacco roots and stems were both fast in the early stage and slow in the later stage, the cumulative release rate of each nutrient was nitrogen (N) > phosphorous (P)> potassium (K), the decomposing rate and nutrient release of tobacco roots were both slower than those of tobacco stems; after tobacco residues returning to field for 120 days, the cumulative decomposing rate of tobacco roots and stems was 45.02% and 53.82%, respectively; (2) returning tobacco stems and roots to field could increase the soil organic matter content by 9.35%-39.87%, the soil pH would decrease at the beginning, but increase after 90 days; (3) nicotine was released fast from tobacco residues, after tobacco residues returning to field for 5 days, about 50% of nicotine was released, and the nicotine in the tobacco residues was basically released after 40 days; nicotine from tobacco roots was released faster than that of tobacco stems, after 30 days, the cumulative nicotine release rate of tobacco roots and stems was 96.95% and 94.03%, respectively, and the nicotine content of each treatment soil was 0 μg/g after 90 days; rice plants absorbed trace amount of nicotine in the early stage, but the content of nicotine in the rice plants was 0 μg/g after 20 days. Overall, returning tobacco residues to field could improve soil nutrients, and there will be no nicotine residue in soil and rice plants in the later stage.