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.

In order to evaluate the biological control potential of Penicillium purpurogenum against tobacco root-knot nematode disease, the activity of P. purpurogenum K1 against the second stage juveniles and eggs of Meloidogyne incognita were tested in laboratory, and the control effect of P. purpurogenum K1 on tobacco root-knot nematode disease was tested in 2 fields for 2 years. The results were obtained as follows. (1) P. purpurogenum K1 strain had strong virulent activity against M. incognita. The corrected mortality rate of the second stage juveniles of M. incognita at 48 h was 94.53%, and the relative inhibition efficiency of egg hatching was 90.75%. (2) The control effects of P. purpurogenum with three application rates on tobacco root-knot nematode disease, and the comprehensive agronomic traits, yield and quality, and average price of flue-cured tobacco were better than those of Paecilomyces lilacinus treatment with the application rate of 33.00 kg/hm². The control effect of P. purpurogenum at the rate of 41.25 kg/hm² was the best with an average control effect of 80.60%, and the comprehensive agronomic traits, output value and average price of tobacco under this treatment were the best. The tobacco leaf yield, output value and average price were 2119.50 kg/hm², 56762.77 yuan/hm² and 26.78 yuan/kg, respectively. Therefore, P. purpurogenum K1 has great potential of biological control of tobacco root-knot nematode in field, and it can be developed and applied as biocontrol fungi against tobacco root-knot nematode disease in Panzhihua. The recommended application method is using 41.25 kg/hm²P. purpurogenum K1 at tobacco transplanting.

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.

To clarify the control effects of three Bacillus subtilis strains on powdery mildew of flue-cured tobacco variety ‘Yunyan 87’, suspensions, bacterial suspension, and suspension agent (SC) prepared by B. subtilis and low-toxic chemical pesticides were used as test materials to carry out research on their control effects on powdery mildew. The indoor results showed that: YWF-19-0068, YWF-19-0070 and YWF-19-0071 biocontrol agents of 10 times dilution had the control effect of 70.49%, 61.15% and 69.71%, respectively. And 50 times dilution of bacterial suspension agents had the germination inhibition rate on the powdery mildew spore of 56.92%, 56.92% and 58.46%, respectively. The outdoor results showed that: 10 days after the application of the three biocontrol agents at different dosages, the control effects of 50 times dilution of bacterial suspension agents were the best of 46.85%, 65.50%, and 51.70%, respectively. After full and half doses of thiophanate were used once, YWF-19-0070 (SC) was applied once every 3 days. 10 days after the last application, the control effect of the full dosage thiophanate methyl treatment was more than 77.73%, and the control effect of the half dosage thiophanate methyl treatment was more than 60.23%.

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.

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.

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.

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.

Tobacco virus disease (tobacco mosaic virus, cucumber mosaic virus, potato virus Y, etc.) is one of the most common tobacco diseases in the world, which often causes great loss in tobacco production. In order to understand the spatial distribution of tobacco virus disease in field, this paper analyzed the ecological niche characteristics of virus disease pathogens through field systematic investigation. The results show that the host ecological niche breadth of tobacco virus disease is large in Longyan tobacco planting area. With the growth of tobacco, the ecological niche breadth of tobacco virus disease gradually increases, and the value in the later growth stage is close to 0.9, indicating that the virus disease could infect most of the tobacco in the area. At the same time, the ecological niche breadth of the incidence of cucumber mosaic virus disease is 0.94, and that of common mosaic virus disease is 0.8256, indicating that the spread rate of cucumber mosaic disease is faster than that of common mosaic disease. The research on the ecological niche of infectious diseases could provide a basis for the effective ecological regulation of diseases.

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.

Tomato spotted wilt virus (TSWV) and potato virus Y (PVY) are the main virus diseases of tobacco in Yunnan, the research aims to screen highly effective agents to control the virus on tobacco, thereby reducing the economic losses of tobacco. Through field plot tests, the control effects of 1% lentinan aqueous solution, 3% harpin protein, 5% amino oligosaccharide water and 2% cytosintetidemycin on TSWV and PVY were investigated. The results showed that the four agents had certain preventing and control effects on TSWV and PVY. The control effect of 1% lentinan aqueous solution, 3% harpin protein, 5% amino oligosaccharide water and 2% cytosintetidemycin was 31.11%-39.90%, 54.34%-59.91%, 8.69%-38.21% and 22.75%-43.32% on TSWV, respectively, and 55.08%-71.06%, 68.10%-82.24%, 37.76%-55.36% and 58.07%-68.86% on PVY, respectively. Among them, the control effect of 3% harpin protein was the best, which was over 50% and 60% on TSWV and PVY, respectively, followed by that of 2% cytosintetidemycin, which was over 22% and 58% on TSWV and PVY, respectively.

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.

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.

To utilize endophytic Bacillus amyloliquefaciens YN2014042 (YN42) isolated from tobacco, the colonization and growth promotion of YN42 were studied. We successfully obtained a stable GFP tagged strain YN42-GFP by using natural transformation with pHAPII plasmid introduced into YN42. Inhibition activity showed that the strain YN42-GFP exhibited the comparable ability as the wild type strain YN42 to inhibit13 pathogenic fungi such as Phytophthora parasitica var. nicotianae and Fusarium graminearum. When YN42-GFP was irrigated to tobacco and maize seedlings with 1.00×10 ⁷ CFU/g, its colony number was respectively 1.89 × 10 ⁶ CFU/g, 1.07×10⁴ CFU/g and 0.93×10³ CFU/g of tobacco root, stem and leaf tissues on the 50^th day, and the colony number was 6.67×10³CFU/g of maize leaf on the 25^th day after inoculation, indicating that YN42 could colonize stably in both its indigenous host and non-host plants. When wild type of YN42 was added to tobacco seedling substrate with 1.00×10⁷ CFU/g, the plant type height and fresh weight of aerial parts of 45-day-old tobacco seedling increased by 450.58% and 756.52%, respectively. When maize was drenched with 1.00×10⁷ CFU/g, the plant type height and fresh weight of aerial parts of 30-day-old maize seedling increased by 19.37% and 61.42%, respectively. In conclusion, YN42 not only have a significant inhibitory effect on a variety of plant pathogens but also could colonize well in tobacco and maize, and promote the growth of tobacco and maize. YN42 has a good application prospect in agricultural production.

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.

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.

The main objective is to investigate the effect of a new soil conditioner on root development and tobacco quality and explore the fertilizer’s role in improving acidified soil. With ‘NC55’ as the test material, different dosages of silicon calcium potassium magnesium fertilizer gradient (0, 750, 1500, 2250 kg/hm²) treatment were set up in field to determine the agronomic indexes and root morphology and root physiological activity indexes by systematic sampling according to different organs of the plant. Experimental results showed that: the addition of silicon calcium potassium magnesium fertilizer improved the root development and tobacco quality within the range of gradient treatment. It showed that the root was stronger, the agronomic characters were significantly improved, tobacco quality and economic benefits were improved, and the chemical composition was more coordinated. With the increase of the dosage of silicon calcium potassium magnesium fertilizer, all the tested indexes showed a trend of rising first and then decreasing. Among them, the treatment dosage of 1500 kg/hm²was the best. Compared with the treatment without the application of silicon calcium potassium magnesium fertilizer, the morphological index of root increased by 25.06%, the physiological activity of root increased by 28.62%, the potassium content of leaves increased by 0.35 percentage points, the potassium content of leaves decreased by 0.35 percentage points, the output value increased by 3486.88 yuan/hm², the average price increased by 1.23 yuan/kg, and the proportion of topped tobacco increased by 6.9 percentage points. But the dosage should be adjusted according to the soil pH and the specific acidification degree.

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 screen out the effective fungicides to control tobacco bacterial wilt caused by Ralstonia solanacearum, the toxicity of five fungicides, including streptomycin sulfate, ethylallicin, octyllamine acetate, Kejunkang and Qingkuling, to tobacco bacterial wilt bacteria was determined with plate inhibition zone method while their efficacy was tested by pot experiment in greenhouse by inoculating pathogen first and then irrigating drugs. The results showed that the five fungicides could inhibit the growth of tobacco bacterial wilt. There was a significant positive correlation between the concentration of fungicides and the inhibition effect. The correlation between the concentration of fungicides and the inhibition effect was significant. The EC₅₀ of 72% Streptomycin sulphate, 80% ethylallicin, 1.8% octyllamine acetate, 3% Kejunkang and 50% Qingkuling was 43.50, 154.69, 116.75, 123.43 and 37.86 mg/L, respectively. Pot experiment showed that 50% Qingkuling had the highest inhibition rate against tobacco bacterial wilt, with the control efficacy of 88.6%; followed by 72% streptomycin sulfate, with the control efficacy of 79.6%. 1.8% octyllamine acetate, 80% ethylallicin and 3% Kejunkang had poor control effects on tobacco bacterial wilt with control efficacy of 75.6%, 56.7% and 52.3%, respectively.

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.

The effect of different mulching types on soil environment and growth of flue-cured tobacco was studied by field experiment. The no coverage, ordinary film mulching, three-dimensional film covering and straw mulching were carried out to clarify their ecological effect in tobacco field. The results showed that the soil temperature of different soil layers under different mulching types had similar trend, and the soil temperature decreased with the increase of soil depth, and the temperature changes of different soil layers under the same mulch type were consistent. The heat insulation effect of ordinary film mulching on soil temperature was the best, which could promote tobacco seedlings to grow quickly and early, but the high surface temperature at the rosette stage under mulching might affect the root growth. The effect of straw mulching on soil temperature during the growth period was relatively good, and the soil temperature of three-dimensional covering was the lowest of all during the early growth of flue-cured tobacco. Ordinary film mulching was not conducive to absorption the atmospheric rainfall into ridge soil, its soil water content was the lowest, meanwhile, it could avoid the soil nutrient leaching. Straw mulching had the best effect on soil moisture storage, followed by three-dimensional film covering. The ordinary film mulching was the most conducive to the growth of flue-cured tobacco at the rosette stage, followed by the straw mulching, and then the three-dimensional covering. The worst tobacco growth was found in the non-mulching treatment. And the straw mulching treatment had the highest root shoot ratio among all treatments. The results indicate that the effect of three-dimensional mulching on soil temperature and humidity and the growth and development of flue-cured tobacco at rosette stage is lower than that of ordinary film mulching. Further research should be carried out on the whole growth and development period of flue-cured tobacco, the characteristics of yield and quality, and the cost-benefit and environmental impact of mulching.

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.

The mixed vinegar was made from straw of Artemisia annua and Nicotiana tabacum, and its effect on the growth of Fusarium tricinctum was studied. Fungi were isolated and purified, and strains were identified using the methods of traditional morphological and molecular. The straw vinegar of A. annua and N .tabacum was prepared by distillation method. Concentration gradient was set to observe the effects of the straw vinegar on the growth of these two fungi. The two strains were both identified as F. tricinctum. The relative correction rate of the growth inhibition rate was approximately 100% at 50% concentration of the vinegar, which achieved the effect of complete inhibition. The study provides technical references for the research and development of the potential utilization value of straw of A. annua and N. tabacum.

To explore the differences of leaf volatile constituents and the sources of aromatic characteristics in different types of tobacco leaves, Tenax-TA was used to adsorb volatiles in different types of tobacco leaves by the dynamic headspace procedure. The components and contents were analyzed by gas chromatography-mass spectrometry. The results showed that there were differences in the volatile components and contents of different types of tobacco leaves. A total of 51 volatiles were detected in‘Yuyan 11’, 50 volatiles were detected in‘8306’, 48 volatiles were detected in‘Yunyan 87’, 44 volatiles were detected in‘Yueyan 98’, and 43 volatiles were detected in‘K326’. A total of 34 volatiles were detected in the sun-cured tobacco, and 25 volatiles were detected in the oriental tobacco. Among them, 17 unique compounds were identified in the flue-cured tobacco, six unique compounds were identified in the sun-cured tobacco, and 4 unique compounds were identified in the oriental tobacco. The conclusion reveals that the discovery of these compounds is closely related to the aromatic characteristics of different types of tobacco.

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.

Aiming at the diseases that appear in gene editing tobacoo materials, based on the differential analysis, we developed a high-throughput FTIR primary screening method based on the characteristics of tobacco material diseases as the core of research. Based on the premature flowering and normal seedling formation period study, showed that tobacco leaf carbohydrates increased significantly after premature flowering, while the protein content did not change significantly, ratio of sugar to protein increased significantly. The carbohydrates may be premature flowering tobacco plants flowering signal factor. Study on the chlorisis leaves and normal leaves showed that the carbohydrate in chlorisis leaf decreased significantly, and the protein content was basically unchanged. While the nitrate was enriched in chlorisis leaves, which may be due the photosynthesis decreased in chlorisis leaves, the absorption and assimilation of plant nitrate were decreased, but the assimilation decreased more significantly, therefore, the nitrate was enriched in chlorisis leaves. It is also possible to block or reduce the assimilation of nitrate in plants due to the editing of gene loci. The enrichment of nitrate in tobacco leaves can be used as a preliminary screening criterion for this type of chlorisis disease, and the characteristic peaks of the chlorisis tobacco were in 1384 cm-1 and 829 cm-1. In addition, the changes in the chemical composition are verified by other analytical methods and the results are consistent. The principal component analysis showed that the disease tobacco could be distinctly distinguished from the control tobacco, and a preliminary determination model of the related diseases tobacco was established. The results showed that the analysis results of FTIR technology had high accuracy, and the difference between them was obvious. It could be applied to high-throughput primary screening for early disease diagnosis and disease analysis of gene editing tobacco materials.

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.

An ion chromatographic method for the determination of potassium, sodium, calcium, magnesium and ammonia in tobacco was developed. The potassium, sodium, calcium, magnesium and ammonia were extracted from the samples by ultrasonic extraction with 5% hydrochloric acid solution in an extraction bottle with solid phase extraction and purification function, and the extract were purified by solid phase extraction with graphitized carbon black. The purified samples were separated on an IonPacCS12A (3?150 mm，5 μm) cation ion exchange column with 30 mM methanesulfonic acid as mobile phase. The five cation ion (K+、Na+、Mg2+、Ca2+、and NH4+) were separated within 5.0 min. The sample extraction, purification, and filter can be completeed in our self-designed extraction bottle without any sample transfer. Compared with the conventional method, the operation process is simplified and the efficiency is greatly improved in new method. In addition, the new method has high sensitivity and high recovery, and provides a high-throughput analysis method for the rapid determination of potassium, sodium, calcium, magnesium and ammonia in gene editing materials.

To investigate the content of plastid pigments in tobacco leaves at different maturity，the tobacco cultivars ‘K326’、‘ Jiucaiping2’、‘Honghuadajinyuan’、‘ Guiyan2’、‘ Nangjiang3’、‘ Bina1’were used as experimental material and the comparative study ofthe content and forms of plastid pigments in tobacco leaves at different mature stage was carried. The results indicated that there was significant difference in chromoplast pigment of different genotypes during maturity of tobacco leaves and the content of chromoplast pigment of different genotypes decreased during maturity of tobacco leaves but different degradation rates of chromoplast pigment of different genotypes. Then different flavor quality and style of different genotypes was showed because of the content of degradation products.And there was extremely significant correlation among the chromoplast pigment of different genotypes during maturity of tobacco leaves. The rapid detection technology of maturity may be expressed by one ofchromoplast pigment. These results are important toimprove the selection and evaluation of tobacco varieties of tobacco fragrance quality and fragrance quantity, and provide the basis for rapid detection of tobacco leaves maturity and classification of tobacco leaves.

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.

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 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.

In this paper, through the field plot experiment, we study the influences of reducing pesticide combined with pyroligneous acid and charcoal and foliage spraying pyroligneous acid on tobacco agronomic traits, yield, quality, disease, and economic effects. [Result]The results shows that: compared with complete use of pesticides, reducing pesticides combined with pyroligneous acid and charcoal and foliage spraying pyroligneous acid can improve agronomic traits during vigorous growth period and inhibit the occurrence of diseases, without obvious changes in yield, quality and output value. [Conclusion]Pesticides of 10-20% reduction combined with the considerable amount foliage spraying pyroligneous acid can assure tobacco normal growth and satisfying demand of yield, quality and economic effects.

The paper aims to verify the control efficacy of predatory mites against thrips at tobacco seedlingstage. The authors investigated the occurrence and species of thrips and comparatively studied the control efficacy of release quantities, methods and carried microbial agents of different predatory mites in Zhongshu, Luxi, Yunnan. The results showed that: the main species of thrips was Frankliniella occidentalis (Pergande), followed by Thrips flavidulus (Bagnall), the thrips reached the highest peak in mid-April; the release of 100 mites Amblyseius cucumeris (Oudemans) per tray provided the best control efficacy among different release quantities, and the uniform broadcast method was significantly (P<0.05) more effective than placed with an open bag and CK; the control efficacy of predatory mites carried with Beauveria bassiana Vuillemin was the best, and the control efficacy of predatory mites carried with Metarhizium anisopliae Sorokin were parallel to that without microbial agent, whereas both were significantly more effective than CK (P<0.05).

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.

This research aims to select and identify tobacco germplasms which have different sensitivities to low temperature in flower bud differentiation. Tobacco recombinant inbred lines LM2 and HM1 are used as materials, and their seedlings are treated under low temperature and room temperature, and then transplanted into field. The growth of meristem is observed dynamically under the stereomicroscope. The results showed that the flower bud differentiation process of LM2 under low temperature treatment was similar to that in the room temperature. The low temperature treatment for LM2 at seedling stage had no effect on the flower bud differentiation process. The floral primordium of LM2 was formed after transplanted into field for 30 days, began differentiating after 35 days, and the small flower primordia were developed after 40 days. However, the flower bud differentiation process of HM1 under low temperature treatment was different from that of the room temperature. Under low temperature treatment, HM1 entered the initiation stage of flower bud differentiation after transplanted for 25 days, got in the inflorescence primordium formation stage in the 35th day, and entered the flower organ development stage in the 40th day. It indicated that the HM1 and LM2 lines were a couple of special germplasm which had differences in low temperature sensitivity, they could be used to analyze the mechanism of flower bud differentiation in responding to low temperature at seedling stage, and breed tobacco variety flowering early and resistant to low temperature.

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.

In order to improve the early warning and prevention system of tobacco mosaic disease, the early responsive proteins in tobacco infected by TMV were screened through detecting the proteome changes. [Methods] iTRAQ was used to analyze the proteome changes and the genes expression was detected with qPCR method. [Results] Proteomic analysis showed that there were 160 differentially expressed proteins, including 64 up-regulated and 96 down-regulated proteins. The functions of these differential proteins were related to redox balance, RNA decay, stress response, chloroplast structure and photosynthesis. qPCR results demonstrated that the change trend in mRNA expressions of these differential proteins was consistent with iTRAQ data. Tobacco mosaic disease could be effectively controlled by timely application of antiviral agents and plant resistance inducers, which induced the changes in expression of PR10, LHCB, POD, HSP90, 14-3-3 and AGO1. [Conclusion] Some early responsive proteins were identified in tobacco infected by TMV, which will be helpful for clarifying the pathogenesis mechanism of tobacco mosaic disease and screening new antiviral agents and plant resistance inducers.

The aim is to identify the integrated effect of Crotalaria pallida and Paecilomyces lilacinus against tobacco root- knot nematode disease. The root powders of C. pallida were used as materials to study the influences on the growth, sporulation quantity, spore- germination rate of P. lilacinus, and Meloidogyne incognita J2 corrected death. While three treatments (single intercropping C. pallida, single using P. lilacinus, intercropping C. pallida at the same time using P. lilacinus) were set to make a comprehensive evaluation on integrated C. pallida and P. lilacinus against tobacco root- knot nematode disease. The results showed as follows: (1) the root powders of C. pallida promoted the growth, sporulation quantity, and spore-germination rate of P. lilacinus, under the treatment of 24 h and 0.01 g/mL root powders water extracts of C. pallida and P. lilacinus spore for Meloidogyne incognita J2, the corrected death rate was 96.08%; (2) tobacco intercropping with C. pallida and using P. lilacinus simultaneously could significantly increase the plant height and maximum width of tobacco leaves, the control efficiency was 67.5%, increased by 22.9% and 10.2% compared with single intercropping C. pallida and single using P. lilacinus, respectively. Taken together, C. pallida and P. lilacinus have obvious synergistic effect on controlling tobacco root-knot nematode disease.

The paper aims to explore the relation of morbidity degree of brown spot with varieties and topping time of tobacco. An experiment was conducted with the split plot design to study the effect of different varieties and different topping time on morbidity degree of brown spot. Three varieties‘( Yunyan 87’,‘Yunyan 97’and ‘K326’) were taken as the main plot, and three topping methods (at squaring stage, initial flowering stage and full-bloom stage) were adopted as the split plot. The results showed that:‘Yunyan 97’displayed the strongest resistance to tobacco brown spot, followed by‘K326’, and‘Yunyan 87’had the weakest resistance. Topping at full-bloom stage had the best control effect on tobacco brown spot morbidity for‘Yunyan 87’and‘K326’, and topping at initial flowering stage had the best effect for‘Yunyan 97’, while topping at squaring stage had the worst effect. According to the practical situation of tobacco planting area in Qidong and with overall consideration of tobacco yield and quality, the optimum way is topping at initial flowering stage for‘Yunyan 97’, ‘Yunyan 87 ’and‘K326’.