Crop rotation patterns have important effects on crop growth and disease occurrence, but there is a lack of understanding of how crop root systems and inter-root environments affect the bacterial communities involved in plant disease resistance under different crop rotation patterns. In this study, two crop rotation patterns, tobaccorice (TR) and tobacco-maize (TM), were set up in a tobacco growing region of southern China, and the differences in soil bacterial communities and the mechanisms of their influence on the occurrence of tobacco diseases were investigated under the two rotation patterns. The results showed that the disease incidence rate of tobacco under TR crop rotation was low, only 4.92 %, while the incidence rate under TM crop rotation was as high as 34.44 %. The bacterial genera affecting the disease incidence of tobacco were identified through microbial network and correlation analysis, and a total of 12 genera were identified as significantly correlated with the disease incidence rate of tobacco in the soil layers of 0-10 cm and 10-20 cm. Of these, four genera (Acidothermus, Chujaibacter, Rhodanobacter, and Nitrospira) were significantly and negatively correlated with the incidence rate, and also more abundant in the bacterial community of TR. Soil nitrogen nutrients and pH were the main soil factors influencing the differences in bacterial communities between the two rotation patterns. Partial least squares path model (PLS-PM) analysis revealed that the key bacterial taxa directly influenced the disease incidence of tobacco in both the 0-10 cm and 10-20 cm soil layers. Interestingly, the key bacterial taxa were directly influenced by soil nutrients in the 0-10 cm soil layer and by the tobacco root system in the 10-20 cm soil layer. In summary, nitrogen-rich nutrients and well-developed plant root systems are conducive to shaping soil bacterial communities with disease-resistant properties, reducing the disease incidence of tobacco. This study also provides new research perspectives for sustainable agricultural development and crop disease control.

A highly sensitive and selective molecularly imprinted polymer (MIP) sensing platform was developed for the detection of nicotine in tobacco samples. The MIP sensor was fabricated by integrating a PtNPs/GO nanocomposite with an electropolymerized nicotine-imprinted film on a glassy carbon electrode. Under optimal conditions (pH 7.4, 50mM pyrrole, and 30min elution time), the MIP sensor exhibited a wide linear range (0.01-0.5μM and 0.5-100μM), low detection limit (0.015μM), good reproducibility (RSD < 4.2%), and long-term stability (93.2% retention after 30 days). The MIP sensor demonstrated excellent selectivity towards nicotine, with selectivity coefficients ranging from 7.2 to 9.5 against interfering substances. The practical applicability of the MIP sensor was validated by analyzing nicotine content in cigarettes and chewing tobacco samples, with recoveries ranging from 97.5% to 102.8% and relative errors within ±5% compared to the reference GC-MS method. The proposed MIP-based electrochemical sensing platform offers a rapid, simple, and cost-effective approach for sensitive and selective detection of nicotine in complex tobacco matrices, showing great potential for applications in the tobacco industry and public health sector.

The pressures from machinery use and continuous agricultural production practices exacerbate soil compaction. Deep tillage (DT) can reduce subsoil compaction, but the spatial composition patterns and community assembly mechanisms of subsoil vs. topsoil bacteria mediated by DT are unknown. Here, we collected soil profile samples from 18 agricultural fields within a multiple cropping area of southern China to investigate the status of soil compaction. The effects of DT on soil physicochemical properties and bacterial communities at different soil depths were investigated by establishing three long-term experimental sites, and the spatial composition mechanisms of the bacterial community were preliminarily explored. Our results showed that soil compaction occurred at soil depths greater than 20 cm, as evidenced by higher soil bulk density, and sharp decreases in water and nutrient contents and bacterial community diversity. Although the ameliorative effect of DT on deep soil compaction diminished in the fourth year, the water and organic matter content and bacterial alpha diversity remained high. DT resulted in a more homogeneous bacterial community across the soil profile in terms of community similarity and compositional stability, along with increased alpha diversity, all of which were associated with reduced heterogeneity in the soil variables, increased soil organic matter content, and the importance of homogeneous selection in the community assembly mechanism. Additionally, the homogenization of bacterial communities under DT may promote enhancement of bacterial network complexity and stability. Collectively, our findings reveal the importance of deep tillage for deep soil improvement and spatial homogenization of bacterial communities, which has far-reaching implications for comprehensively understanding the spatial dynamics and assembly mechanisms of tillage-mediated soil microbial communities in agroecosystems.

[目的]探究会理烟区海拔高度与烤烟质量、风格特征和代谢物的关系.[方法]在会理烟区海拔1550～2300 m范围内,以云烟87为研究材料,研究会理烟区不同海拔高度对烤烟的常规化学成分、感官质量和代谢组学的影响.[结果]较高海拔更有利于烤烟总糖、还原糖和石油醚提取物的积累,而烟碱和总氮则与之相反,糖碱比与海拔极显著相关,呈强正相关;随着海拔升高,烤烟香气质改善、香气量增多、杂气增加、清甜香型风格更典型,但劲头有所降低;通过OPLS-DA模型共筛选出28个差异代谢物,其中,低海拔地区烤烟的烟碱和与其关系密切的烟酸、麦斯明表达量较高,中海拔地区烤烟的壬酸、己酸等有机酸类物质含量最丰富,高海拔地区烤烟的苯甲醇、苯乙醇、麦芽醇等醇类物质和新植二烯、二氢大马酮、大马酮、β-紫罗兰酮、二氢猕猴桃内脂等质体色素降解产物相对含量最高;差异代谢物被注释到碳水化合物代谢、氨基酸代谢、萜类和聚酮化合物代谢等6条B级代谢通路,其中,海拔高度的变化对烟叶碳水化合物代谢和氨基酸代谢的影响最显著.[结论]总糖、还原糖、糖碱比、醇类和质体色素降解产物含量的升高是高海拔地区烤烟感官质量改善、风格特征更彰显的重要原因,因此,适当提高会理烟区植烟海拔有利于提升产区烤烟质量和彰显其清甜香型风格.

探究肥料因子对会理产区烤烟生长发育及产量品质的影响,为当地合理施肥提供理论依据.以云烟87为试验材料,通过田间试验,研究不同比例有机肥与氮肥配施对烤烟生长发育及产量品质的影响,并通过构建正交偏最小二乘法回归(OPLS)模型分析烤烟中多酚、有机酸和质体色素含量与感官质量的关系,探究不同处理导致的感官质量差异的化学层面原因.结果表明,当有机肥比例为50％、施氮量为96 kg/hm2时,烟叶的农艺性状较好,中上等烟比例最高,常规化学成分指标更符合优质烤烟的要求;烤后烟叶的叶片结构疏松、油分最多且色度较浓,外观质量达到最优;烟叶的香气质最好、香气量最足,刺激性最小、杂气最轻;在OPLS回归模型中,烤烟中芸香叶苷、绿原酸、莨菪亭、乙酸、琥珀酸含量对感官质量总分有较大影响,且呈正相关关系,同时验证了在有机肥比例为50％、施氮量为96 kg/hm2时,其芸香叶苷、绿原酸、莨菪亭及乙酸含量最高,感官综合质量也最好.由研究结果可知,在当前其他栽培技术条件不变的情况下,会理产区云烟87施用有机肥比例为50％、施氮量为96 kg/hm2时的综合效果较为理想.

[目的]探明养分水平对烤烟根系性状及其对养分吸收的影响,为烤烟高产栽培与合理施肥提供依据.[方法]以云烟87为材料,研究NPK Hogland全营养液、1/2 NPK Hogland全营养液和1/4 NPK全营养液处理烟株的根系形态、农艺性状、生理指标及养分吸收的变化.[结果]各处理株高、茎围、叶片数、最大叶面积和叶片干重分别为40.5～48.0 m、7.1～7.6 mm、13.3～13.7片、450.7～576.4 cm2和21.5～32.4 g,均以NPK Hogland全营养液处理效果最佳;侧根和不定根一二级分枝根密度分别为1.4～1.7条/cm、2.2～3.0条/cm 和 1.8～2.7条/cm、3.0～4.1 条/cm,均为 1/4 NPK Hogland 全营养液＞1/2 NPK Hogland全营养液＞NPK Hogland全营养液;地上部和根系NPK浓度与积累量均为NPK Hogland全营养液＞1/2 NPK Hogland全营养液＞1/4 NPK Hogland全营养液;净光合速率及相关酶的活性均为NPK Hogland全营养液＞1/2 NPK Hogland全营养液＞1/4 NPK Hogland全营养液.[结论]NPK Hogland全营养液处理烟株的农艺性状、地上部和根系NPK浓度与积累量、净光合速率和相关酶活性均优于1/2 NPK Hogland全营养液和1/4 NPK Hogland全营养液,1/4 NPK Hogland全营养液处理烟株的一二级分枝根密度与根毛密度最大.

为掌握烟区土壤化学性状特征,2015年对永州市79个种烟乡镇689个植烟土壤取样调查和统计分析.结果 表明,烟区土壤pH偏高,土壤有机质和阳离子交换量(CEC)丰富,分别有92.6％的土壤有机质和91.6％的CEC处于中等级别以上水平,植烟土壤肥力水平较高.土壤pH、有机质和CEC均存在正相关关系.通过聚类分析将烟区划分为2大特征区域,因地制宜,合理施肥及土壤保育.

[目的]筛选出适宜广东种植的晒黄烟品种.[方法]对大叶青梗、81-26、小叶青梗3个晒黄烟新品种进行大田试验,调查研究其农艺性状、经济性状、物理性状、化学成分、感官质量等各指标的差异.[结果]3个参试的晒黄烟品种中,81-26农艺性状较好,株高、茎围、最大叶面积优于其他品种;大叶青梗经济性状表现最佳,产量、产值分别为1612.56 kg/hm2、78483.30元/hm2,显著优于81-26与小叶青梗,并且外观质量表现最好.小叶青梗总糖与还原糖含量最高,81-26总植物碱与全钾含量较高,不同晒黄烟品种化学成分均较为协调.工业评价方面,81-26的含梗率低,工业利用性好;大叶青梗评吸质量最佳,具体表现为浓度适中、香气饱满、杂气少.[结论]3个晒黄烟品种中,大叶青梗最适宜在广东南雄种植.

针对福建武平烟区土壤酸化严重,土壤有效镁含量偏低导致烟叶镁含量低的问题,研究了3种不同镁肥对土壤和烤后烟叶中微量元素含量以及烤烟产质量的影响.结果表明,施用不同镁肥后均能显著提高土壤交换镁的含量,但不同镁肥对提高土壤交换镁含量的时效不同.各处理土壤其它中微量元素含量以施用硫酸镁的土壤较高,施用氢氧化镁的土壤偏低.烤后烟叶的镁含量以氧化镁处理最高,其次为氢氧化镁.施用镁肥会影响烟叶其它中微量元素的含量,其中施用氢氧化镁会导致中上部烟叶钙铁含量轻度缺乏,而施用硫酸镁会导致烟叶中锌锰含量过高.各处理中以氧化镁处理烟叶化学成分含量最适宜,且经济性状最优.因此,在福建武平烟区建议施用氧化镁,既可以防止烤烟生育前期有效镁的淋失,又可以提高烟叶的产量和质量.

[目的]为探索不同播期与移栽方式对烤烟生长发育及产质量的影响.[方法]设置不同播期与移栽方式,分析了烟株的农艺性状及经济指标,并通过赋值法探究烤后烟叶化学品质协调性及烟叶外观质量.[结果]随着播期的推迟,烟株的大田生育期缩短,中山试验区11月25日及永平11月30日播期的膜下移栽组合处理成熟期农艺性状、干物质积累量、经济性状及外观质量最优.烟叶化学品质受播期及移栽方式的影响,随着移栽期的推迟,总糖和还原糖呈先上升后下降的趋势,淀粉含量、总氮含量和烟碱含量逐渐下降,而钾含量和氯含量则增加;膜下移栽处理提高了总糖和还原糖含量,降低了烟叶淀粉含量.[结论]中山试验区11月25日播期及永平11月30日播期的膜下移栽处理下烤烟化学成分协调性及外观质量指数综合评分较高,烟叶品质较好.

The effects of planting density and remained leaf number on agronomic traits and chemical composition of K326, a flue-cured tobacco variety, are studied by a field test to discuss the relationships between quality flue-cured tobacco production and population density, remained leaf number in mountainous area of Western Hunan.Results: The planting density and remained leaf number have the significant influence on agronomic traits of flue-cured tobacco plants and the great influence on chemical composition of flue-cured tobacco plants.The total sugar, reducing sugar content and sugar/nicotine ratio of flue-cured tobacco leaves with different position increase with increase of planting density when the remained leaf number is 20.The sugar/nicotine ratio of flue-cured tobacco leaves is the highest (16.28) when the planting density is 18 518 plants/hm2 and its chemical composition harmony and leaf quality are the best among all treatments.The population structure including 18 518 plants/hm2 of planting density, 120 cm×45 cm of row spacing and 20 remained leaves is suitable for flue-cured tobacco production in flue-cured tobacco-growing area of Western Hunan.

为进一步提高龙岩烟区的烟叶质量,改善烟叶原料的等级结构和部位结构,筛选出适宜龙岩烟区的优化措施.在龙岩武平以云烟87为材料,设6个处理.AI:摘1片顶叶,除1片脚叶;A2:摘1片顶叶,除两2片脚叶(CK);A3:摘2片顶叶,除1片脚叶;A4:摘2片顶叶,除2片脚叶;A5:摘2片顶叶,除3片脚叶;A6:摘3片顶叶,除3片脚叶;研究了田间不同优化烟叶结构措施对烤烟的化学成分、中性香气物质含量及主要经济性状的影响.结果表明:A4处理的类西柏烷类产物、棕色化反应类产物含量最高,分别比对照高了9.89％和6.87 ％;A6处理的类胡萝卜素类产物、苯丙氨酸类产物、其他类香气物质含量较高,相比对照分别提高了68.48％、45.54％和87.06％;香气总量以A6处理最高,其次为A5处理;化学成分方面,A5处理一定程度上降低了淀粉、总氮、烟碱的含量,提高了钾的含量,对提高烟叶燃烧性,降低烟叶吸食中的刺激性和改善烟气的舒适度有利.经济性状方面,A5处理在总产值没有下降的前提下,上等烟比例提升了11.71％,中上等烟比例提升了2.37％,中部烟比例增加了12.95％,上部烟的比例下降了11.02％.综合来看,A5处理香气量较足,化学成分协调,同时显著改善了等级结构和部位结构,适宜在龙岩烟区生产中应用.

Objective] To study the effects of different cultivation technique measures on economic traits of flue-cured tobacco and tobacco leaf structure, and to explore a supporting cultivation technique measure suitable for the structural optimization of tobacco leaves in Wuping Production Area in Fujian Province.[Method] With main cultivar Yunyan 87 in Wuping production area as the research material, orthogonal test with four factors and three levels were adopted.Effects of fertilization mode, topping stage, remained leaves and cutting bottom leaf stage on the main eco-nomic characters of flue-cured tobacco and structure characteristics of optimized tobacco leaves were researched.[ Result] The four factors had impacts on the economic characters of flue-cured tobacco and tobacco leaf structure.However, remained leaves were the leading factor.Fertiliza-tion mode had equal influencing degree to topping time.Finally, the optimal cultivation technology combination was A2 B3 C1 D1 in Wuping produc-tion area of Fujian Province, which was 50% basal application (N,K), basal application of P fertilizer, 50% topdressing (N,K), fertilizing a-mount (N, K) was 90% in production, first flower-topping, 15 leaves left, removing foot leaves while topping.[Conclusion] The optimal culti-vation technology combination is A2 B3 C1 D1 in Wuping production area of Fujian Province, which is verified useful for improving the yield and quality compared with local CK by large-scale test.Its high-class leaf proportion and middle-class leaf ratio are higher than those of CK.Mean-while, sensory quality rating was higher than CK.Treatment A2 B3 C1 D1 is finally approved to be suitable for large-scale application.

To investigate the effects of tobacco organizational structure development and chemical composition with different planting density and N application rate.Field experiment was carried out using Yueyan 98 as planting materials.Set up six different planting densities and N application processing.Respectively,in leaf length 30 cm, fixed length,mature collected in the upper and central part of fresh leaves and use paraffin methods,observe the or-ganizational structure.The results showed that the thickness of palisade tissue,spongy tissue thickness,leaf thick-ness,palisade tissue density with the increase of planting density decreases with increasing nitrogen rate increases;the thickness of palisade tissue,spongy tissue thickness,leaf thickness,palisade tissue density,SLW and tobacco quality indicators total sugar,reducing sugar content,starch content was significantly or very significantly negatively correlated with nicotine content,total nitrogen content were significantly or very significantly positively correlated ex-cept for individual date;after roast total sugar content,sugar content,starch content increased with the increase of planting density and nitrogen application rate decreases,the nicotine content and total nitrogen content increased with planting density decreases with increasing nitrogen rate increases.By changing the planting density and nitro-gen application rate can be varied leaf development characteristics of the organizational structure,internal coordina-tion chemical composition of tobacco,and ultimately improve the quality of tobacco.

In order to find out the causes of color fading of cured tobacco leaves, the factors, including light irradiation, temperature, relative humidity, pH, metal ion and reductant on the stability of carotenoids in cured leaves were investigated. The results showed that:1) The degradation of carotenoids in cured leaves positively correlated to light intensity during storage, it was slower when leaves were stored away from light. 2) Low storage temperature facilitated to the alleviation of carotenoid degradation, while high storage temperature accelerated carotenoid decomposing. 3)Dry environment was beneficial to the stability of carotenoids, while the degradation of carotenoids was accelerated by humid environment. 4) Cu2+, Fe2+, Fe3+, Zn2+ and Al3+ undermined the stability of carotenoids, while the other metal ions did not. 5)Reductant had certain protective effects on carotenoids. Therefore, it is suggested to store cured leaves at alow temperature, away from light, dry and alkaline environment, or after reductant treatment. Lower the contents of Cu2+, Fe2+, Fe3+, Zn2+ and Al3+ in tobacco leaves via agricultural cultural practices would be helpful to the inhibition of carotenoid degradation and color fading of tobacco.

为探究不同群体特征对烤烟生育期光合生产及产量和品质的影响,以云烟87为材料,通过设置不同播期与种植密度来构建不同烤烟群体,分别在烟株移栽后各生育时期完成光合生产相关指标测定及对烤后烟叶进行经济性状分析.结果表明:随着播期的推迟,烤烟大田期缩短,群体于物质积累量降低,叶面积系数(LAI)、光合势(LAD)降低,净同化率(NAR)、作物生长率(CGR)在现蕾-成熟期显著提高,16 500株/hm2种植密度下成熟期烟株群体干物质积累量最高,降低种植密度可显著提高烟株中部干物质积累量、NAR、群体平均叶倾角(MLIA)、烟叶均价、中上等烟比例和中部烟比例,但会降低LAI、LAD、CGR、消光系数(K);种植密度过大会导致烤烟中上等烟比例、中部叶比例降低.当播种期为11月24日左右、植烟密度为16 500株/hm2时,能有效改善烤烟在生育期的群体光合生产各项指标,前期物质生产量适宜,中后期适时缓增,干物质总量大且部位分配合理,其经济性状较优,有效缓解烤烟等级结构及部位结构矛盾.

为研究13株植物根际促生细菌(PGPR)产生的挥发性物质(VOCs)对拟南芥的生长促进作用,通过二分格培养法筛选出对拟南芥生长有影响的菌株,采用SPME-GC-MS对植物根际促生细菌产生的VOCs进行鉴定.结果表明,供试的13株植物根际促生细菌产生的VOCs能够不同程度的促进拟南芥的生长、改变拟南芥的根构型.P1、MD8和FGH19菌株产生的挥发性物质对拟南芥的促生作用十分显著,平均拟南芥鲜重达38.78、30.58、23.70 mg/株,分别比对照增加了5.71、4.29、3.10倍.DZQ8菌株处理的拟南芥PRL为8.03 cm,比对照处理增长了0.85倍,TZQ33和TZQ36菌株的处理对拟南芥LRN影响最为明显,LRN分别为37.50和40.50,比对照处理分别增长了1.17和1.35倍,MTQ8、MD8、TZQ33和TZQ36菌株处理的拟南芥LRD分别为6.20、7.07、7.35和7.33 cm-1,比对照处理分别增大了0.55、0.77、0.84和0.83倍.因此,植物根际促生细菌产生的一些挥发性物质可以促进植物的生长、重塑根构型.通过对挥发性物质的分析及验证,首次发现MTQ8产生的1,3-丁二醇对拟南芥植株有很明显的促生作用,且确定1,3-丁二醇可以促进拟南芥的生长、调整根构型.

The Y-P22 was identified as Brevundimonas diminuta based on morphological characteristics, physiological and biochemical characteristics and 16S rDNA sequence. The strain was isolated from the tobacco phyllosphere. It can produce cytokinin. The results of field experiment and tobacco sensory evaluation showed that the strain could effectively improve the availability of tobacco and the quality of tobacco.

Objective In order to solve the problems existing in the production of flue-cured tobacco a-bout low nitrogen use efficiency ( NUE) and inferior quality of flue-cured tobacco by unreasonable fertili-zing technology .[Method] A variety ( Yunyan87 ) was used as a material in the field experiment .The technology of real time nitrogen management ( RTNM) was applied in Meizhou .Two application modes of fertilizer (S40 and S43) based on SPAD(Soil and Plant Analyzer Development )value, the conventional application of fertilizer by farmer ( CK2) and no fertilizer ( CK1) were designed to study the influences of different application modes of fertilizer on the agronomic traits , nitrogen use efficiency (NUC), yield and quality .[Result and conclusion] The areas of the middle and upper leaves increased by adopting RT-NM, and the other agronomic traits had no significant differences compared with CK 2.The NUE was ele-vated obviously under RTNM , and the absorption of nitrogen of S 40 and S43 increased by 48 .74% and 45.42%compared with CK2, respectively.The yield and output value of tobacco leaf under RTNM in-creased more than those of CK 2 and S43 achieved the highest yield and output value of tobacco leaf .Re-sults indicated that , compared with the conventional application of fertilizer by farmer , RTNM could en-hance high yield and output value of flue-cured tobacco and improve utilization rate of nitrogen fertilizer . Therefore, RTNM, especially based 43, is effective in practice and good for popularization at Meizhou Guangdong production area according the local condition .

[Objective] The aim was to study the adaptation,economic benefit,quality features and industrial applicability of flue-cured tobacco varieties meeting brand requirements of China Tobacco Guangdong Industrial Limited Company. [Method]Under the specific ecological condition of Zunyi tobacco-growing base in Guizhou Province,the comparative test for flue-cured tobacco varieties Zunyan No. 6,Yunyan87, K326 and Nanjiang No. 3 was carried out. [Result]The results showed that Zunyan No. 6 and Nanjiang No. 3 had better agronomic characters,and higher yield and production value. The chemical compositions and smoking quality of K326,Yunyan87 and Zunyan No. 6 were better,which could meet the raw material demand of‘Shuangxi'brand cigarette by China Tobacco Guangdong Industrial Limited Company. In general,Zunyan No 6 as one of major tobacco variety at the Zunyi base of Guangdong Tobacco Company,under the specific ecological condition of Zunyi tobacco-growing base in Guizhou province. [Conclusion]Zunyi No. 6 can be used as one of the key varieties of Zunyi tobaccogrowing base in Guizhou Province under the local special ecological condition.