Effects of Chronic Stress of Cadmium and Lead on Anatomical Structure of Tobacco Roots

Cadmium （Cd2＋） is one of the major widespread environmental pollutants, and can cause serious problems to all organisms. Lead （Pb2＋） is another wide spread dangerous heavy metal. Tobacco is a popular growing economic crop in China. Most tobacco growing region soils contain excessive Cd2＋ and Pb2＋. To assess anatomic changes of tobacco roots under Cd2＋, Pb2＋, and Cd2＋＋pb2＋ chronic stress, a pot experiment was carried out in field. The tobacco seedlings with 6 leaves were transplanted to pots in which soil was placed. The amounts of Cd2＋ added to soil were 0, 3, 6, 10, 30, 60, and 100 mg kg-1 dry soil. The amounts of Pb2＋ added to soil were 0, 150, 300, 450, 600, 750, and 1 000 mg kg-1 dry soil. The amounts of Cd2＋＋Pb2＋ added to soil were 0＋0, 3＋150, 6＋300, 10＋450, 30＋600, 60＋750, and 100＋1000 mg kg-1 dry soil. The contents of Cd2＋ and Pb2＋ in root systems were determined by inductively coupled plasma, and the anatomical structure was studied by method of paraffin sectioning. The results revealed that the amounts of exchangeable Cd2＋ and Pb2＋ and carbonate bound Cd2＋ and Pbz＋ in soil increased with the amounts of Cd2＋ and Pb2＋ added to soil, and the contents of both Cd2＋ and Pb1＋ in roots were significantly increased along with stress time and the amounts of Cd2＋ and Pb2＋ added to soil. The growing of tobacco in Cd2＋ and Cd2＋＋Pb2＋ polluted soil for 50, 100, and 150 d resulted in some abnormal extemal morphological and anatomical changes in ripe region of lateral roots. All the abnormal roots had abnormal vascular cylinders, and the ratio of abnormal extemal morphological and anatomical changes of roots positively correlated with the Cd2＋ contents in roots and stress time. While, there were no abnormal external morphological and anatomical changes of roots under Pb2＋ stress. It was suggested that Cd2＋ stress could cause abnormal anatomic changes of roots, but Pb2＋ stress could not.

Proteomics Identification of Differentially Expressed Proteins Relevant for Nicotine Synthesis in Flue-Cured Tobacco Roots Before and After Decapitation

Nicotine is a secondary substance synthesized in tobacco roots. In flue-cured tobacco planting, tobacco decapitation is an effective practice to promote nicotine biosynthesis by regulation of the redistribution of total nitrogen amounts. However, proteins relevant to nicotine synthesis in tobacco roots has not been identified and characterized yet. It is important to explore the regulation of nicotine biosynthesis in tobacco roots. To identify the proteins relevant to nicotine synthesis, the protein patterns in roots of flue-cured tobacco （cv. K326） before and after decapitation were analyzed. In the present study, the protein patterns in roots of flue-cured tobacco were analyzed by two-dimensional electrophoresis （2-DE）, and the differentially-expressed spots were identified by matrix assisted laser desorption ionization time of flight mass spectrometry （MALDI-TOF-MS）. Paired comparison of 2-DE maps revealed 26 spots of differentially-expressed proteins in roots before and after decapitation. Furthermore, nine differentially-expressed spots were identified. There were four proteins which were enzymes possibly involved in nicotine biosynthesis. In addition, the roles of the four enzymes in nicotine biosynthesis were discussed in a putative network. Our results would contribute to the understanding of the regulation pathway of nicotine biosynthesis and further to the molecular manipulation on the nicotine contents in flue-cured tobacco.

Differential responses of root growth to nutrition with different ammonium/nitrate ratios involve auxin distribution in two tobacco cultivars

Nitrogen(N), the major forms of which are nitrate(NO3–) and ammonium(NH4+), plays an important role in plant growth and mediation of root development. However, the role of auxin in root growth in response to different NH4+/NO3– ratios remains unclear. Two tobacco cultivars(Nicotiana tabacum L.) were adopted in this study, which displayed variant growth features under the situations with sole NO3– nutrition ratio(NH4+/NO3– ratio: 0/100), low NO3– nutrition ratio(NH4+/NO3– ratio: 97/3), and optimal NH4+/NO3– ratio(50/50). We investigated the effects of the different NH4+/NO3– ratios on the formation and elongation of lateral roots(LRs), auxin concentration, DR5::GUS expression, 3 H-labeled indole acetic acid([3 H]IAA) transport, and the expression of six PIN genes in tobacco roots. We also examined the effects of exogenous auxin and a transport inhibitor on LRs growth. The results are shown as follows, compared to optimal N nutrition conditions, the biomass and nitrogen(N) accumulation were largely reduced by sole and low NO3– nutrition treatment in NC89, but no difference was observed in Zhongyan 100. In most cases, sole and low NO3– nutrition impaired the elongation and formation of firstorder lateral roots(1° LRs), only in NC89, thus reducing the root growth. IAA concentration and DR5::GUS expression levels decreased in roots when NC89 was subjected to sole and low NO3– nutrition media, suggesting that different NH4+/NO3– ratios affect the transport of auxin from leaves to roots. Results were similar following exogenous NAA application to low NO3– nutrition treated seedlings. Based on direct [3 H]IAA transport measurement, the transport of polar auxin from shoots to roots decreased due to low NO3– nutrition. PIN4 expression levels were markedly decreased in roots of NC89by sole and low NO3– nutrition, while they were unaffected in Zhongyan 100 roots. Overall, our findings suggest that LRs formation in tobacco seedlings is regulated by NH4+/NO3– ratios via modifying polar transport of auxin.

Morphology and Molecular Identification of Root-knot Nematode in Partial Tobacco-growing Areas in Yunnan Province

[Objectives]The species and distribution of root-knot nematodes in tobacco growing regions of Yunnan were investigated,in order to provide reference for comprehensive prevention of root-knot nematodes disease and tobacco variety layout. [Methods]Fifty-four samples of root-knot nematode host on tobacco crops were collected from Kunming,Qujing and Yuxi cities in Yunnan from August to October in 2015. The species of root-knot nematodes were identified by observing perineal patterns and molecular biological testing（ PCR of ribosomal DNA of ITS region and sequence characterized amplified region,SCAR）. [Results] There were 24 samples belonging to Meloidogyne arenaria,accounting for 44. 44%; seven M. incognita samples,accounting for 12. 96%; one M. javanica sample,accounting for 1. 85%. Eleven samples were compound populations of M. javanica and M. arenaria,accounting for 20. 37%. Five were compound populations of M. incognita and M. arenaria,accounting for 9. 26%. Three were compound populations of M. incognita and M. javanica,accounting for 5. 56%. Three belonged to compound population of M. incognita,M. javanica and M. arenaria,accounting for 5. 56%. [Conclusions] The species of root-knot nematodes in tobacco growing areas of Yunnan mainly include M. incognita,M. javanica and M. arenaria. M. arenaria is the dominant population.

Com parison of Amino Acids in Root Exudates of Flue-cured Tobacco Varieties with Different Resistances against Black Shank

In order to explore the differences of amino acids in root exudates and plant tissues, we selected four flue-cured tobacco varieties [ Yunyan 87 （ Ⅰ）, K326 （Ⅱ）, NC102（Ⅲ）, Hongda （Ⅳ）] as the test materials and studied the components and mass fractions of amino acids in rhizosphere soil, non rhizosphere soil, roots and leaves via high performance capillary zone electrophoresis. Ten amino acids were detected out from four varieties, including histidine, lysine, tryptophan, phenylalanine, valine, threonine, proline, serine, alanine and glycine. The mass fractions of amino acids in leaves and roots were higher than those in rhizosphere soil and non rhizosphere soil. In rhizosphere soil and non-rhizosphere soil, the mass fractions of lysine, phenylalanine, threonine, proline and glycine in susceptible varieties （ Ⅲ, Ⅳ） were higher than those in resistant varieties （ Ⅰ, Ⅱ）. In rhizosphere soil, the total amino acids successively were Ⅳ 〉 Ⅲ 〉 Ⅰ 〉 Ⅱ, and in non rhi- zosphere soil were Ⅲ 〉 Ⅳ 〉 Ⅰ 〉 Ⅱ. The total amino acids in roots of variety Ⅳ was the highest, up to 6 359. 195 μg/g. In leaves, the total amino acids in varieties I and If were higher than those in varieties IfI and IV. The results indicated that amino acids could secrete to rhizosphere via root secretion, and the compositions and mass fractions of amino acids varied with flue-cured tobacco varieties, thus the secretion amount of susceptible varieties was higher than that of resistant varieties.

棘孢木霉与30%霜霉·嘧菌酯协同防治烟草镰刀菌根腐病

为筛选防治烟草镰刀菌根腐病高效、安全的复配剂,采用菌丝生长速率法测定生防棘孢木霉Tr-0111、化学杀菌剂30%霜霉·嘧菌酯对尖孢镰刀菌(Fusarium oxysporum)的毒力及两者的相容性,同时测定两者混配对尖孢镰刀菌的毒力系数,并通过盆栽试验评价其对烟草镰刀菌根腐病的防治效果。结果表明,30%霜霉·嘧菌酯和棘孢木霉Tr-0111对尖孢镰刀菌均具有较强的毒力,其EC50值分别为0.0643 mL/L、2.36×10^(2)cfu/mL,且两者相容性好。除V30%霜霉·嘧菌酯∶V_(Tr-0111)=4∶6时无增效作用,其他8个混配比例均具有增效作用,其中V_(30%霜霉·嘧菌酯)∶V_(Tr-0111)=7∶3时增效比率最高,为1.16,抑菌率为68.37%。盆栽试验结果表明,V_(30%霜霉·嘧菌酯)∶V_(Tr-0111)=5∶5时,对烟草镰刀菌根腐病的防效最好,为78.18%,其次为7∶3和1∶9,防效分别为77.27%和72.73%,均显著高于单一使用30%霜霉·嘧菌酯和棘孢木霉Tr-0111。因此,可以将0.0643 mL/L 30%霜霉·嘧菌酯和2.36×10^(2)cfu/mL棘孢木霉Tr-0111以5∶5比例混匀复配应用于烟田防治烟草镰刀菌根腐病,减少化学农药使用。

连作烟草根系分泌物鉴定及潜在化感物质的筛选研究

为探索长期连作状态下烟草根系分泌物内含有的化感物质组成成分,设置石英砂栽培和连作土壤栽培2种烟草培养处理,对2种烟草不同生长时期的根系分泌物进行提取,利用超高效液相色谱串联质谱(ultra-high performance liquid chromatography tandem mass spectrometry,UHPLC-MS/MS)对提取的根系分泌物进行分析,通过数据库比对、差异分析和时间聚类分析等方法筛选连作烟草根系分泌物中潜在的化感物质。结果表明,共筛选出11类潜在化感物质,分别为生物碱、萜类、胺类、有机酸、苯酸及其衍生物、脂肪酸、酚类、氨基酸和多肽、香豆素、肉桂酸及其衍生物和其他。生物碱、萜类、胺类和有机酸4类化合物相对含量占所有化合物的73.3%。L-烟碱、熊果酸、β-氨基丙腈、5-羟基吲哚乙酸、早熟素Ⅱ、单乙基己基邻苯二甲酸、己内酰胺、姜酚、L-乳酸、邻苯二甲酸二乙酯和2,3-二氢-3,5-二羟基-2-氧代-3-吲哚乙酸甲酯是连作烟草根系分泌物中相对含量较高的潜在化感物质。研究结果为烟草根系化感物质的化感作用研究及缓解烟草连作障碍方法研究提供理论基础。

五种烟草根茎病害病原菌多重PCR检测方法的建立与应用

为了快速准确鉴别烟草根腐病菌(Fusarium oxysporum)、黑胫病菌(Phytophthora nicotianae)、立枯病菌(Rhizoctonia solani)、根黑腐病菌(Thielaviopsis basicola)和鸢尾丝囊霉菌(Aphanomyces iridis)等5种烟草根茎病害病原菌,利用RAPD分子标记等方法筛选和设计特异性扩增引物,优化多重PCR扩增体系中各引物添加量、退火温度、循环数等条件,建立多重PCR检测体系,并对其检测的可行性进行验证。本研究筛选并设计出F.oxysporum、P.nicotianae、R.solani、T.basicola和A.iridis的特异性引物对LD141 F/R、YM1002 F/R、LK111 F/R、GHFT F/R、AiT7 F/R,PCR反应体系中最佳引物组合浓度分别为1.0、1.0、0.2、0.5、0.5μmol/L,最适退火温度为54℃,最佳循环数为28,可同时扩增出大小分别为370、240、536、783、138 bp的特异性片段,能同时检出5种病原菌DNA的最低限值为0.5 ng/μL,可实现对烟草育苗基质和烟株中5种病原菌的快速检测,对烟草苗期根茎病害的早期预防具有重要意义。

不同基因型烤烟对镰刀菌根腐病的抗性鉴定与评价

为明确不同基因型烤烟对烟草镰刀菌根腐病的抗性,利用10个烟草品种(系),采用粗毒素幼芽接种、带菌菌谷接种、孢子悬浮液培养等方法进行抗性鉴定。结果表明,供试品种对尖孢镰刀菌抗性表现出显著差异;对尖孢镰刀菌表现出抗的品种(系)有4个,分别是‘Y2001’、‘Y2002’、‘长脖黄’、‘664-01’;对尖孢镰刀菌表现出感的品种(系)有6个,分别是‘7710’‘、7713’‘、Y2007’‘、Y2008’‘、中烟100’、‘小黄金1025’。3种接种方法鉴定结果基本一致,共筛选出4个抗性品种(系)。

烟草镰刀菌根腐病生防菌GDND-2的鉴定及防病效果

为烟草根腐病生防菌剂的研发储备菌株资源。以烟草根腐病菌为靶标,筛选拮抗菌,通过培养形态、生化特征和分子技术鉴定菌株。用平板划线测定拮抗菌耐受力,盆栽试验验证其对病害的防效。筛选出拮抗菌GDND-2,其10%和20%发酵滤液对病菌生长抑制率为53.09%和62.24%。鉴定GDND-2为贝莱斯芽孢杆菌(Bacillus velenzensis),该菌抑菌谱广,耐极端温度、酸碱和盐碱,对多菌灵等7种常用杀菌剂不敏感。GDND-2发酵液处理15、30、45 d,对烟草根腐病的防效为70.00%、74.62%和79.51%,处理45 d的防效高于多菌灵。贝莱斯芽孢杆菌GDND-2抗菌谱广,性状优良,可有效防治烟草根腐病,有望开发为生防菌剂。

寡糖联合淡紫紫孢菌对化学杀线剂防治烤烟根结线虫病效果的影响

为更好地控制烟草根结线虫的危害,降低化学杀线剂的用量,将寡糖免疫诱导剂与噻唑膦、阿维菌素及淡紫紫孢菌协同使用进行田间小区试验,研究其对烟草根结线虫的防治效果。结果表明,壳寡糖15 L/hm^(2)、几丁寡糖15 L/hm^(2)分别与噻唑膦22.5 kg/hm^(2)协同使用,对烟草根结线虫的防治效果高于噻唑膦单独使用效果。相对防效由噻唑膦单独使用的45.20%分别提高到64.42%和65.38%。进一步试验发现,几丁寡糖1 kg/hm^(2)、淡紫紫孢菌15 kg/hm^(2)及噻唑膦16.875 kg/hm^(2)(减少25%)协同使用,对烟草根结线虫病相对防效及对烟草生长总体效应优于与噻唑膦正常用量(22.5 kg/hm^(2))组和噻唑膦减少50%(11.25 kg/hm^(2))组合效果。寡糖诱导剂单独或与淡紫紫孢菌协同使用,显著提高了噻唑膦对烟草根结线虫病的防治效果,减少了农药使用量,为烟草根结线虫病害的防控提供了一种新的技术手段。

湖南烟草镰刀菌根腐病病原鉴定及防治药剂筛选

为明确湖南郴州和永州地区烟草根腐病的病原种类,针对主要病原菌筛选有效的防治药剂,分别利用组织分离法和平板稀释法对两地主要烟区采集的烟草根腐病病样和根际土壤进行病原分离,通过形态学观察、翻译延伸因子1A(EF-1α)序列进化分析以及致病性测定确定病原种类,采用生长速率法测定供试杀菌剂对主要病原菌菌丝生长的抑制效果,并通过活体盆栽防效试验验证候选杀菌剂对主要病原菌的防治效果。共分离到真菌128株,其中镰刀菌87株,包括共享镰刀菌Fusarium commune、甜瓜镰刀菌Fusarium incarnatum、藤仓镰刀菌Fusarium fujikuroi、茄镰刀菌Fusarium solani、层出镰刀菌Fusarium proliferatum、Fusarium falciforme、Fusarium humuli共7个种。其中,F.commune占比最高,为39.08%,其次为F.solani和F.incarnatum,占比均为14.94%。致病力测定结果表明,这些菌株都能引起烟草发病,明确其为烟草根腐病的病原物。F.commune对40%咪鲜胺EW、43 g/L戊唑醇SC和15%氰烯菌酯SC高度敏感,EC50分别为0.026、0.079和0.169μg/mL。盆栽试验结果表明,40%咪鲜胺EW的防治效果最为显著,相对防效达到94.43%±2.79%,其次为43 g/L戊唑醇SC和15%氰烯菌酯SC,相对防效为88.63%±1.68%和83.07%±2.55%。本研究表明,湖南郴州和永州地区烟草镰刀菌根腐病病原真菌以共享镰刀为主,供试药剂中,40%咪鲜胺EW对该病原菌的抑菌效果最好。

滴灌施肥频率对烤烟生长、氮肥利用及烟叶产质量的影响

为探明滴灌施肥频率对烤烟生长、氮肥利用及烟叶产质量的影响,2018-2019年通过田间试验,以不施肥空白(CK)和当地常规处理(CF,即肥料干施+滴灌)为对照,研究低频滴灌施肥(DF1,即养分管理期1次滴灌施肥)、中频滴灌施肥(DF2,即养分管理期连续2天每天1次滴灌施肥)和高频滴灌施肥(DF3,即养分管理期连续3天每天1次滴灌施肥)对烤烟农艺性状、根系发育形态、氮肥累积量和利用效率及烟叶产质量的影响。结果表明,与CF相比,各滴灌施肥处理烟叶产量无显著差异(P<0.05),氮肥利用率有不同程度提高,烟株发育状况则因滴灌施肥频率而异。与DF1和DF2相比,DF3烟株旺长期叶面积系数分别增加了7.3%~33.3%和1.6%~28.7%,根系体积分别增加了3.9%~46.6%和21.2%~40.5%,氮素利用率分别提高了39.0%~95.0%和21.5%~34.3%,烟叶烟碱含量分别增加了17.5%~28.5%和12.5%~20.0%。与中频滴灌施肥和低频滴灌施肥相比,高频滴灌施肥有利于促进烟株生长和根系形态发育,提高氮肥利用效率和烟叶品质质量,是有效协同氮肥高效利用和烟叶产质量的滴灌施肥措施。

生物炭肥对易感根结线虫病烤烟根际菌群和理化性质的影响

为明确生物炭肥对烟草根结线虫病及根际土壤的影响,通过田间试验研究拌塘施用不同量生物炭肥对烟草根结线虫病株根际土壤的影响。结果表明,常规施肥减量10%拌塘施用酵素生物炭肥能够显著降低烟草根结线虫病的病情指数,其中酵素生物炭肥施用量为350 g·株^(-1)时,根结线虫病防治效果较好,防治效果达23.98%,且烟株农艺性状表现较好;根际土壤中过氧化氢酶、脲酶和磷酸酶活性较高,酚酸物质含量降低,化感自毒作用减弱。各处理土壤真菌数量均随生育期的推进呈先增高后降低趋势,其中酵素生物炭肥施用量为350 g·株^(-1)时,根际土壤中的细菌量随生育期推进逐步降低。各生育期土壤中均表现为真菌数量较高,细菌数量较低,真菌/细菌值较高,说明在烟草种植中,减量施肥10%同时拌塘施用酵素生物炭肥350 g·株^(-1)能提高土壤中真菌数量,降低土壤中细菌数量,显著提高土壤肥力及土壤酶活性,为生物炭肥对易感根结线虫病根际微生态调控提供了科学依据。

根结线虫病对烟草植株根际土壤微生物群落及其功能的影响

为明确烟草植株根际土壤微生物对烟株根结线虫病的响应特征,采用Illumina MiSeq高通量测序技术测定健康烟株(FH-H)、发病烟株(FH-D)根际土壤细菌16S rDNA和真菌内转录间隔区(ITS)序列,测定其根际土壤理化性质和酶活性,并借助PICRUSt2软件和FUNGuild数据库进行分析。结果表明,与健康烟株相比,发病烟株根际土壤pH、硝态氮含量、碱解氮含量、过氧化氢酶活性和微生物群落α多样性显著降低;发病烟株根际土壤微生物种类和相对丰度发生改变,细菌群落中放线菌门、厚壁菌门、芽孢杆菌属和Unclassified_Ktedonobacteraceae属相对丰度均显著升高,真菌群落中子囊菌门、担子菌门、青霉属、粗糙孔菌属相对丰度均显著升高。发病烟株根际土壤细菌群落在碳水化合物代谢、氨基酸代谢、辅助因子和维生素代谢等功能丰度上显著高于健康烟株根际土壤,功能真菌类型的相对丰度明显区别于健康烟株根际土壤,其中腐生营养型功能真菌相对丰度显著高于健康烟株根际土壤。方差分解分析结果表明,土壤有效磷含量对烟株根际土壤细菌相对丰度影响最大,烟株根际土壤真菌相对丰度主要与土壤脲酶活性、土壤硝态氮含量和土壤酸碱度有显著相关性。本研究结果为根结线虫病的绿色防控和土壤保育提供了理论依据。

腐植酸水溶肥对高海拔烤烟生长及品质的影响

重庆市黔江烟区为高海拔多雨烟区,烟苗移栽前后气温较低,不利于其生长发育,为改善这一现状,于2022年施加含腐植酸水溶肥料的生根剂。在烟苗移栽后分为4个浓度处理:CK(0 mg/L)、T1(60 mg/L)、T2(90 mg/L)、T3(120 mg/L),灌根喷施,每个小区按照T1、T2、T3处理的浓度施加50 L;并从农艺性状、初烤烟叶的外观质量、化学成分和经济性状等指标探究腐植酸对烤烟品种云烟87产量和质量的影响。T2和T3处理的各方面皆优于T1处理和对照,在农艺性状及田间生长势方面T2与T3处理基本相同,T3处理株高及叶面积稍高于T2处理;各部位烟叶干鲜比T2处理较好;烤后烟叶的化学成分中,C3F等级烟叶T2处理最佳,B2F等级烟叶T3处理烟碱及氮含量稍高于T2处理;T2与T3处理烟叶评吸质量相差不大,T2处理香气质及香气量稍多;经济价值方面,T2处理产量、产值均为最佳。经对比分析得出,T2处理为最佳浓度处理。

不同生境下烤烟三段式育苗微生物群落变化及抗逆酶活分析

【目的】为解析三段式育苗对烟苗根际微生物多样性和抗逆酶活性的影响。【方法】以中烟100为供试品种,以常规漂浮育苗为对照,设置三段式育苗。通过监测工厂化四联体育苗大棚中烟苗的生长发育情况,系统分析了三段式育苗方式对育苗环境,育苗池、基质和根系微生物多样性,烟苗农艺性状和抗逆酶活性的影响。同时,追溯分析三段式育苗对于田间烟草根际土壤微生物多样性的影响。【结果】幼苗期,三段式育苗方式相对于漂浮育苗对照,改善了育苗池水体的理化性状,降低了育苗大棚内的温差和湿度水平,日均温差由19.23℃下降至17.95℃,日均湿度由75.17%RH下降至69.53%RH;成苗期,三段式育苗增加了育苗池水体中的短波单胞菌属(Brevundimonas)和赖氨酸芽孢杆菌属(Lysinibacillus)的丰度,分别为漂浮育苗的13.90倍和4.66倍。增加了烟苗的鲜重、根长、侧根数、CAT酶活性、SOD酶活性、POD酶活性、根活力和成苗率,较漂浮育苗对照分别提高了34.33%、34.37%、36.41%、31.91%、25.34%、58.07%、29.08%和10.91%,MDA含量降低了22.31%;大田期,提升了烟草根际土壤微生物子囊菌门和青梅属的丰度,创造了更有利的烟草生长环境。【结论】三段式育苗通过改善育苗环境,增加了烟苗根际有益菌群的丰度,显著提高了烟苗的成苗期农艺性状和抗逆酶活性,从而提升烟苗素质。

烟草嫁接组合对根结线虫病的抗性鉴定

在温室对以品种G278、G279、板桥B为砧木,以品种K326、红花大金元、云烟87为接穗的9个烟草嫁接组合进行盆栽试验,接种最常见的南方根结线虫,采用病理学指标聚类分析法、生物学指标以及病理学指标隶属函数值法综合评价了烟草嫁接组合对根结线虫病的抗性。结果表明:板桥B+K326、G278+云烟87、G279+K326、G279+云烟87、G278+K326、G278+红花大金元、G279+红花大金元、板桥B+云烟87和板桥B+红花大金元等嫁接组合抗根结线虫病,砧木和接穗品种中K326、G278、G279表现为抗病,云烟87表现为中感,板桥B表现为中抗,红花大金元表现为感病。采用嫁接技术可以有效地增强烟草品种对根结线虫病的抗性。

植物根际促生菌在烟草根茎类病害防治中的应用研究进展

烟草是重要的经济作物,经济价值高。烟草根茎类病害的发生导致一定的烟草损失。本文阐述了烟草根黑腐病、烟草黑胫病和烟草青枯病等烟草根茎类病害的发生和危害,分析了烟草根茎类病害的防治现状,包括农业防治、化学防治和生物防治等内容,提出了植物根际促生菌的研究进展,探讨了其作用机制及在防治烟草病害中的应用前景,总结了用于防治烟草病害的植物根际促生菌主要种类,提出了相关展望,以期为有效防治烟草根茎类病害和推广应用植物根际促生菌提供参考。

促进烟草根系早生快发的移栽基质优化研究

[目的]针对烤烟移栽苗根系前期发育迟缓等问题,研究利用廉价有机材料和腐殖酸改良幼苗移栽基质对烤烟根区水肥环境和烟苗生长的影响,为研制高效和环境友好型烟草幼苗移栽载体奠定基础。[方法]常规移栽基质一般由秸秆、椰糠、草炭以3∶1∶1混合而成,本试验以此基质作基础处理(JYC);另设添加腐殖酸钾(JYCK)、蛭石(JYCZ)、腐殖酸钾和蛭石(JYCZK)处理,以供试土壤为空白对照(CK),当幼苗在移栽基质中生长10、30、50天时,测定土壤理化指标和烤烟生物量,在生长10与50天时,测定烟草根系形态指标。[结果]与CK处理相比,基质移栽在移栽后10天的烟草根生物量和根冠比分别增加了48.3%~62.1%和80.4%~114.4%,烟株根长度和根分支数分别提高了45.9%~128.9%和52.0%~174.3%;移栽后50天的土壤硝态氮和溶解性有机碳(DOC)含量分别提高了62.9%~147.2%和230.3%~399.8%。基于随机森林模型分析,发现移栽基质、土壤温度和溶解性有机碳含量、根长度和根尖数显著影响烤烟地上部生物量;通过相关性分析和结构方程模型分析,发现移栽基质通过改善根区环境,直接或间接影响烤烟根系形态和促进地上部生物量的积累。与CK相比,JYC、JYCK、JYCZ和JYCZK处理的土壤硝态氮含量分别提高了65.2%、147.2%、62.9%和80.0%。JYCZK处理的烤烟根长度比JYC和JYCK处理分别提高了45.0%和30.1%,根分支数分别增加了28.9%和40.8%。[结论]在基础基质中添加0.5%的腐殖酸钾和16.7%的蛭石(体积)能更有效地协调土壤氮素供应水平,优化烤烟根系形态。